Provided by: critcl_3.1.18.1+dfsg-3_amd64 bug

NAME

       critcl - Critcl - Package Reference

SYNOPSIS

       package require Tcl  8.4

       package require critcl  ?3.1.18?

       package require platform  ?1.0.2?

       package require md5  ?2?

       ::critcl::ccode fragment

       ::critcl::ccommand tclname cname

       ::critcl::ccommand tclname arguments body ?option value...?

       ::critcl::cdata tclname data

       ::critcl::cconst tclname resulttype value

       ::critcl::cdefines list of glob patterns ?namespace?

       ::critcl::cproc name arguments resulttype body ?option value...?

       ::critcl::cproc name arguments resulttype

       ::critcl::cinit text externals

       ::critcl::include path

       ::critcl::api import name version

       ::critcl::api function resulttype name arguments

       ::critcl::api header ?glob pattern...?

       ::critcl::api extheader ?file...?

       ::critcl::license author ?text...?

       ::critcl::summary text

       ::critcl::description text

       ::critcl::subject ?key...?

       ::critcl::meta key ?word...?

       ::critcl::meta? key

       ::critcl::buildrequirement script

       ::critcl::cheaders ?arg...?

       ::critcl::csources ?glob pattern...?

       ::critcl::clibraries ?glob pattern...?

       ::critcl::source glob pattern

       ::critcl::tsources glob pattern...

       ::critcl::owns glob pattern...

       ::critcl::cflags ?arg...?

       ::critcl::ldflags ?arg...?

       ::critcl::framework ?arg...?

       ::critcl::tcl version

       ::critcl::tk

       ::critcl::preload lib...

       ::critcl::debug area...

       ::critcl::check ?label? text

       ::critcl::checklink ?label? text

       ::critcl::msg ?-nonewline? msg

       ::critcl::print ?-nonewline? ?chan? msg

       ::critcl::compiled

       ::critcl::compiling

       ::critcl::done

       ::critcl::failed

       ::critcl::load

       ::critcl::config option ?val?

       ::critcl::cache ?path?

       ::critcl::clean_cache ?pattern...?

       ::critcl::readconfig path

       ::critcl::showconfig ?chan?

       ::critcl::showallconfig ?chan?

       ::critcl::chooseconfig target ?nomatcherr?

       ::critcl::setconfig target

       ::critcl::actualtarget

       ::critcl::buildforpackage ?flag?

       ::critcl::cnothingtodo file

       ::critcl::cresults ?file?

       ::critcl::crosscheck

       ::critcl::error msg

       ::critcl::knowntargets

       ::critcl::sharedlibext

       ::critcl::targetconfig

       ::critcl::buildplatform

       ::critcl::targetplatform

       ::critcl::cobjects ?glob pattern...?

       ::critcl::scan path

       ::critcl::name2c name

       ::critcl::argnames arguments

       ::critcl::argcnames arguments

       ::critcl::argcsignature arguments

       ::critcl::argvardecls arguments

       ::critcl::argconversion arguments ?n?

       ::critcl::argoptional arguments

       ::critcl::argdefaults arguments

       ::critcl::argsupport arguments

       ::critcl::userconfig define name description type ?default?

       ::critcl::userconfig query name

       ::critcl::userconfig set name value

       ::critcl::at::caller

       ::critcl::at::caller offset

       ::critcl::at::caller offset level

       ::critcl::at::here

       ::critcl::at::get*

       ::critcl::at::get

       ::critcl::at::= file line

       ::critcl::at::incr n...

       ::critcl::at::incrt str...

       ::critcl::at::caller!

       ::critcl::at::caller! offset

       ::critcl::at::caller! offset level

       ::critcl::at::here!

       ::critcl::collect_begin

       ::critcl::collect_end

       ::critcl::collect script

       ::critcl::make path contents

       ::critcl::has-resulttype name

       ::critcl::resulttype name body ?ctype?

       ::critcl::resulttype name = origname

       ::critcl::has-argtype name

       ::critcl::argtype name body ?ctype? ?ctypefun?

       ::critcl::argtype name = origname

       ::critcl::argtypesupport name code ?guard?

       ::critcl::argtyperelease name code

       ::preload library

_________________________________________________________________________________________________

DESCRIPTION

       C  Runtime In Tcl, or CriTcl , is a system for compiling C code embedded in Tcl on the fly
       and either loading the resulting objects into Tcl for immediate use or packaging them  for
       distribution.  Use CriTcl to improve performance by rewriting in C those routines that are
       performance bottlenecks.

       The critcl package is the core of the system.  For an overview of the complete system, see
       Introduction  To  CriTcl.   For  the  usage  of  the standalone critcl program, see CriTcl
       Application.  This core package maybe be used to embed C code into Tcl scripts.   It  also
       provides  access  to  the  internals  that  other  parts  of the core use and which are of
       interest to those wishing to understand the internal workings of the core and of  the  API
       it provides to the CriTcl Application.  These advanced sections are marked as such so that
       those simply wishing to use the package can skip them.

       This package resides in the Core Package Layer of CriTcl.

       +----------------+
       |Applications    |
       | critcl         |
       | critcl::app    |
       +----------------+

       *================*
       |Core Packages   |
       | critcl         |
       | critcl::util   |
       *================*

       +----------------+
       |Support Packages|
       | stubs::*       |
       | md5, platform  |
       |  ...           |
       +----------------+

API

       A short note ahead of the documentation: Instead of repeatedly talking about "a Tcl script
       with  embbedded  C  code",  or  "a  Tcl script containing Critcl commands", we call such a
       script a Critcl script.  A file containing a Critcl script usually has the extension  .tcl
       or .critcl.

   EMBEDDED C CODE
       The following commands append C code fragments to the current module.  Fragments appear in
       the module in the order they are appended, so the earlier fragments (variables, functions,
       macros, etc.) are visible to later fragments.

       ::critcl::ccode fragment
              Appends  the C code in fragment to the current module and returns the empty string.
              See Runtime Behaviour.

       ::critcl::ccommand tclname cname
              As documented below, except that cname is the name of a  C  function  that  already
              exists.

       ::critcl::ccommand tclname arguments body ?option value...?
              Appends  the  code  to  create  a  Tcl  command named tclname and a corresponding C
              function whose body  is  body  and  which  behaves  as  documented  for  Tcl's  own
              Tcl_CreateObjCommand [https://www.tcl-lang.org/man/tcl/TclLib/CrtObjCmd.htm].

              aguments  is  a  list  of zero to four names for the standard arguments clientdata,
              interp, objc, and objv.  The standard default  names  are  used  in  place  of  any
              missing  names.   This  is  a  more  low-level  way  than critcl::cproc to define a
              command, as processing of the items in  objv  is  left  to  the  author,  affording
              complete  control  over  the handling of the arguments to the command.  See section
              Runtime Behaviour.

              Returns the empty string.

              Each option may be one of:

              -clientdata c-expression
                     Provides the client data for the new command.  NULL by default.

              -delproc c-expression
                     Provides a function  pointer  of  type  Tcl_CmdDeleteProc  [https://www.tcl-
                     lang.org/man/tcl/TclLib/CrtObjCmd.htm]  as the deletion function for the new
                     command.  NULL by default.

              -cname boolean
                     If false  (the  default),  a  name  for  the  corresponding  C  function  is
                     automatically  derived from the fully-qualified tclname.  Otherwise, name of
                     the C function is the last component of tclname.

       ::critcl::cdata tclname data
              Appends the code to create a new Tcl command named tclname which returns data as  a
              ByteArray result.

              Returns the empty string.

       ::critcl::cconst tclname resulttype value
              Appends  the  code  to  create  a  new  Tcl command named tclname which returns the
              constant value having the Tcl type resulttype.   value  can  be  a  C  macro  or  a
              function  call  (including the parentheses) to any visible C function that does not
              take arguments.   Unlike  critcl::cdata,  resulttype  can  be  any  type  known  to
              critcl::cproc.  Its semantics are equivalent to:

                  cproc $tclname {} $resulttype "return $value ;"

       This is more efficient than critcl::cproc since there is no C function generated.

       Returns the empty string.

       ::critcl::cdefines list of glob patterns ?namespace?
              Arranges  for  C  enum  and  #define  values that match one of the patterns in glob
              patterns to be created in the namespace namespace, each variable having the same as
              the  corresponding  C  item.   The  default  namespace  is the global namespace.  A
              pattern that matches nothing is ignored.

              The Tcl variables are created when the module is compiled, using  the  preprocessor
              in order to properly find all matching C definitions.

              Produces no C code.  The desired C definitions must already exist.

       ::critcl::cproc name arguments resulttype body ?option value...?
              Appends  a  function  having body as its body, another shim function to perform the
              needed conversions, and the code  to  create  a  corresponding  Tcl  command  named
              tclname.   Unlike  critcl::ccommand  the arguments and result are typed, and Critcl
              generates the code to convert between Tcl_Obj values and C data  types.   See  also
              Runtime Behaviour.

              Returns the empty string.

              string option
                     Each may be one of:

                     -cname boolean
                            If  false  (the  default), a name for the corresponding C function is
                            automatically derived from the fully-qualified  tclname.   Otherwise,
                            name of the C function is the last component of tclname.

                     -pass-cdata boolean
                            If  false  (the default), the shim function performing the conversion
                            to and from Tcl level does not  pass  the  ClientData  as  the  first
                            argument to the function.

                     -arg-offset int
                            A non-negative integer, 0 by default, indicating the number of hidden
                            arguments preceding the actual procedure arguments.  Used by  higher-
                            order  code generators where there are prefix arguments which are not
                            directly seen by the function but which influence  argument  counting
                            and extraction.

              string resulttype
                     May  be  one  of  the  following predefined types or a custom type.  For the
                     latter see section Advanced: Extending cproc.  Unless otherwise  noted,  the
                     Tcl  return  code  is  always TCL_OK.  Before going into the details first a
                     quick overview:

                     Critcl type   | C type         | Tcl type  | Notes
                     ------------- | -------------- | --------- | ------------------------------
                     void          | n/a            | n/a       | Always OK. Body sets result
                     ok            | int            | n/a       | Result code. Body sets result
                     ------------- | -------------- | --------- | ------------------------------
                     int           | int            | Int       |
                     boolean       |                |           | Alias of int above
                     bool          |                |           | Alias of int above
                     long          | long           | Long      |
                     wideint       | Tcl_WideInt    | WideInt   |
                     double        | double         | Double    |
                     float         | float          | Double    |
                     ------------- | -------------- | --------- | ------------------------------
                     char*         | char*          | String    | Makes a copy
                     vstring       |                |           | Alias of char* above
                     const char*   | const char*    |           | Behavior of char* above
                     ------------- | -------------- | --------- | ------------------------------
                     string        |                | String    | Freeable string set directly
                                   |                |           | No copy is made
                     dstring       |                |           | Alias of string above
                     ------------- | -------------- | --------- | ------------------------------
                                   |                |           | For all below: Null is ERROR
                                   |                |           | Body has to set any message
                     Tcl_Obj*      | Tcl_Obj*       | Any       | refcount --
                     object        |                |           | Alias of Tcl_Obj* above
                     Tcl_Obj*0     |                | Any       | refcount unchanged
                     object0       |                |           | Alias of Tcl_Obj*0 above
                     ------------- | -------------- | --------- | ------------------------------
                     known-channel | Tcl_Channel    | String    | Assumes to already be registered
                     new-channel   | Tcl_Channel    | String    | New channel, will be registered

                     And now the details:

                     Tcl_Obj*

                     object If the returned Tcl_Obj* is NULL, the Tcl return  code  is  TCL_ERROR
                            and  the  function  should  set  an  error  mesage  [https://www.tcl-
                            lang.org/man/tcl/TclLib/SetResult.htm]  as  the  interpreter  result.
                            Otherwise, the returned Tcl_Obj* is set as the interpreter result.

                            Note that setting an error message requires the function body to have
                            access to the  interpreter  the  function  is  running  in.  See  the
                            argument type Tcl_Interp* for the details on how to make that happen.

                            Note further that the returned Tcl_Obj* should have a reference count
                            greater  than  0.  This  is  because  the  converter  decrements  the
                            reference  count  to release possession after setting the interpreter
                            result. It assumes that the function incremented the reference  count
                            of  the returned Tcl_Obj*.  If a Tcl_Obj* with a reference count of 0
                            were returned, the reference count would become 1  when  set  as  the
                            interpreter  result,  and  immediately thereafter be decremented to 0
                            again, causing the memory to be freed.  The system is then likely  to
                            crash  at  some  point  after  the  return  due to reuse of the freed
                            memory.

                     Tcl_Obj*0

                     object0
                            Like Tcl_Obj* except that this conversion assumes that  the  returned
                            value has a reference count of 0 and does not decrement it. Returning
                            a value whose reference count is greater than 0 is  therefore  likely
                            to cause a memory leak.

                            Note that setting an error message requires the function body to have
                            access to the  interpreter  the  function  is  running  in.  See  the
                            argument type Tcl_Interp* for the details on how to make that happen.

                     new-channel
                            A  String Tcl_Obj holding the name of the returned Tcl_Channel is set
                            as the interpreter result.  The channel is further assumed to be new,
                            and therefore registered with the interpreter to make it known.

                     known-channel
                            A  String Tcl_Obj holding the name of the returned Tcl_Channel is set
                            as the interpreter result.  The channel  is  further  assumed  to  be
                            already registered with the interpreter.

                     return-channel
                            This type is a variant of new-channel above.  It varies slightly from
                            it in the registration sequence to be properly complementary  to  the
                            argument type take-channel.  A String Tcl_Obj holding the name of the
                            returned Tcl_Channel is set as the interpreter result.   The  channel
                            is  further  assumed  to  be  new,  and therefore registered with the
                            interpreter to make it known.

                     char*

                     vstring
                            A String Tcl_Obj holding a copy of the returned char* is set  as  the
                            interpreter  result.  If  the  value  is  allocated then the function
                            itself and the  extension  it  is  a  part  of  are  responsible  for
                            releasing the memory when the data is not in use any longer.

                     const char*
                            Like char* above, except that the returned string is const-qualified.

                     string

                     dstring
                            The  returned char* is directly set as the interpreter result without
                            making a copy.   Therefore  it  must  be  dynamically  allocated  via
                            Tcl_Alloc.  Release  happens automatically when the Interpreter finds
                            that the value is not required any longer.

                     double

                     float  The returned double or float is converted to a Double Tcl_Obj and set
                            as the interpreter result.

                     boolean

                     bool   The  returned int value is converted to an Int Tcl_Obj and set as the
                            interpreter result.

                     int    The returned int value is converted to an Int Tcl_Obj and set as  the
                            interpreter result.

                     long   The returned long int value is converted to a Long Tcl_Obj and set as
                            the interpreter result.

                     wideint
                            The returned Tcl_WideInt value is converted to a WideInt Tcl_Obj  and
                            set as the interpreter result.

                     ok     The  returned int value becomes the Tcl return code.  The interpreter
                            result is left untouched and can be set by the function  if  desired.
                            Note that doing this requires the function body to have access to the
                            interpreter the  function  is  running  in.  See  the  argument  type
                            Tcl_Interp* for the details on how to make that happen.

                     void   The function does not return a value.  The interpreter result is left
                            untouched and can be set by the function if desired.

              list arguments
                     Is a multi-dictionary where each key is an argument type and  its  value  is
                     the argument name.  For example:

                      int x int y

              Each argument name must be a valid C identifier.

              If  the  name  is  a  list containing two items, the first item is the name and the
              second item is the default value.  A limited form  of  variadic  arguments  can  be
              accomplished using such default values.  For example:

                      int {x 1}

                     Here x is an optional argument of type int with a default value of 1.

                     Argument  conversion  is  completely  bypassed  when  the  argument  is  not
                     provided, so a custom converter doing validation does not get the chance  to
                     validate  the  default  value.  In this case, the value should be checked in
                     the body of the function.

                     Each argument type may be one of the following predefined types or a  custom
                     type.  For  the latter see Advanced: Extending cproc.  Before going into the
                     details first a quick overview:

                     Critcl type | C type         | Tcl type  | Notes
                     ----------- | -------------- | --------- | ------------------------------
                     Tcl_Interp* | Tcl_Interp*    | n/a       | Special, only first
                     ----------- | -------------- | --------- | ------------------------------
                     Tcl_Obj*    | Tcl_Obj*       | Any       | Read-only
                     object      |                |           | Alias of Tcl_Obj* above
                     list        | critcl_list    | List      | Read-only
                     ----------- | -------------- | --------- | ------------------------------
                     char*       | const char*    | Any       | Read-only, string rep
                     pstring     | critcl_pstring | Any       | Read-only
                     bytes       | critcl_bytes   | ByteArray | Read-only
                     ----------- | -------------- | --------- | ------------------------------
                     int         | int            | Int       |
                     long        | long           | Long      |
                     wideint     | Tcl_WideInt    | WideInt   |
                     double      | double         | Double    |
                     float       | float          | Double    |
                     ----------- | -------------- | --------- | ------------------------------
                     X > 0       |                |           | For X in int ... float above.
                     X >= 0      |                |           | C types as per the base type X.
                     X < 0       |                |           | Allowed argument values are
                     X <= 0      |                |           | restricted as per the shown
                     X > 1       |                |           | relation
                     X >= 1      |                |           |
                     X < 1       |                |           | This is not a general mechanism
                     X <= 1      |                |           | open to other values. Only 0/1.
                     ----------- | -------------- | --------- | ------------------------------
                     boolean     | int            | Boolean   |
                     bool        |                |           | Alias of boolean above
                     ----------- | -------------- | --------- | ------------------------------
                     bytearray   |                |           | DEPRECATED
                     rawchar     |                |           | DEPRECATED
                     rawchar*    |                |           | DEPRECATED
                     double*     |                |           | DEPRECATED
                     float*      |                |           | DEPRECATED
                     int*        |                |           | DEPRECATED
                     void*       |                |           | DEPRECATED

                     And now the details:

                     Tcl_Interp*
                            Attention: This is a special argument type. It can only  be  used  by
                            the  first  argument of a function.  Any other argument using it will
                            cause critcl to throw an error.

                            When used, the argument will  contain  a  reference  to  the  current
                            interpreter  that the function body may use. Furthermore the argument
                            will not be an argument of the Tcl command for the function.

                            This is useful when the function has to do more than simply returning
                            a  value.  Examples would be setting up error messages on failure, or
                            querying the interpreter for variables and other data.

                     Tcl_Obj*

                     object The function  takes  an  argument  of  type  Tcl_Obj*.   No  argument
                            checking  is  done.  The Tcl level word is passed to the argument as-
                            is.  Note that this value must be treated as  read-only  (except  for
                            hidden changes to its intrep, i.e. shimmering).

                     pstring
                            The  function takes an argument of type critcl_pstring containing the
                            original Tcl_Obj* reference of the Tcl argument, plus the  length  of
                            the string and a pointer to the character array.

                            typedef struct critcl_pstring {
                                Tcl_Obj*    o;
                                const char* s;
                                int         len;
                            } critcl_pstring;

                            Note  the  const.  The string is read-only. Any modification can have
                            arbitrary effects, from pulling out the rug under the script  because
                            of  string value and internal representation not matching anymore, up
                            to crashes anytime later.

                     list   The function takes an argument of  type  critcl_list  containing  the
                            original  Tcl_Obj*  reference of the Tcl argument, plus the length of
                            the Tcl list and a pointer to the array of the list elements.

                            typedef struct critcl_list {
                                Tcl_Obj*        o;
                                Tcl_Obj* const* v;
                                int             c;
                            } critcl_list;

                            The Tcl argument must be convertible to  List,  an  error  is  thrown
                            otherwise.

                            Note  the  const.  The  list is read-only.  Any modification can have
                            arbitrary effects, from pulling out the rug under the script  because
                            of  string value and internal representation not matching anymore, up
                            to crashes anytime later.

                     bytearray

                     rawchar*

                     rawchar
                            The function takes an argument of type char*.  The Tcl argument  must
                            be convertible to ByteArray, an error is thrown otherwise.  Note that
                            the length of the ByteArray is not passed  to  the  function,  making
                            this type not very usable.

                            Attention:  These  types are considered DEPRECATED.  It is planned to
                            remove their documentation in release 3.2, and  their  implementation
                            in  release  3.3.   Their deprecation can be undone if good use cases
                            are shown.

                     bytes  This is the new and usable ByteArray type.

                            The function takes an argument of type  critcl_bytes  containing  the
                            original  Tcl_Obj*  reference of the Tcl argument, plus the length of
                            the byte array and a pointer to the byte data.

                            typedef struct critcl_bytes {
                                Tcl_Obj*             o;
                                const unsigned char* s;
                                int                len;
                            } critcl_list;

                            The Tcl argument must be convertible to ByteArray, an error is thrown
                            otherwise.

                            Note  the  const. The bytes are read-only.  Any modification can have
                            arbitrary effects, from pulling out the rug under the script  because
                            of  string value and internal representation not matching anymore, up
                            to crashes anytime later.

                     char*  The function takes an argument  of  type  const  char*.   The  string
                            representation of the Tcl argument is passed in.

                            Note  the  const.  The string is read-only. Any modification can have
                            arbitrary effects, from pulling out the rug under the script  because
                            of  string value and internal representation not matching anymore, up
                            to crashes anytime later.

                     double The function takes an argument of type double.  The Tcl argument must
                            be convertible to Double, an error is thrown otherwise.

                     double > 0

                     double >= 0

                     double < 0

                     double <= 0

                     double > 1

                     double >= 1

                     double < 1

                     double <= 1
                            These are variants of double above, restricting the argument value to
                            the shown relation. An error is thrown for Tcl arguments  outside  of
                            the specified range.  Note: This is not a general range specification
                            syntax. Only the listed types exist.

                     float  The function takes an argument of type float.  The Tcl argument  must
                            be convertible to Double, an error is thrown otherwise.

                     float > 0

                     float >= 0

                     float < 0

                     float <= 0

                     float > 1

                     float >= 1

                     float < 1

                     float <= 1
                            These  are variants of float above, restricting the argument value to
                            the shown relation. An error is thrown for Tcl arguments  outside  of
                            the specified range.  Note: This is not a general range specification
                            syntax. Only the listed types exist.

                     boolean

                     bool   The function takes an argument of type int.  The Tcl argument must be
                            convertible to Boolean, an error is thrown otherwise.

                     channel
                            The function takes an argument of type Tcl_Channel.  The Tcl argument
                            must be convertible to type Channel, an error  is  thrown  otherwise.
                            The  channel  is  further  assumed  to be already registered with the
                            interpreter.

                     unshared-channel
                            This type is an extension of channel above.  All of  the  information
                            above applies.

                            Beyond  that the channel must not be shared by multiple interpreters,
                            an error is thrown otherwise.

                     take-channel
                            This type is an extension of  unshared-channel  above.   All  of  the
                            information above applies.

                            Beyond that the code removes the channel from the current interpreter
                            without closing it, and disables all pre-existing event handling  for
                            it.

                            With  this  the  function  takes  full  ownership  of  the channel in
                            question, taking it away from the interpreter invoking it. It is then
                            responsible  for  the  lifecycle  of the channel, up to and including
                            closing it.

                            Should the system the function is a part of wish to return control of
                            the channel back to the interpeter it then has to use the result type
                            return-channel. This will undo the registration changes made by  this
                            argument  type.   Note however that the removal of pre-existing event
                            handling done here cannot be undone.

                            Attention Removal from the interpreter without closing the channel is
                            effected  by  incrementing  the  channel's  reference  count  without
                            providing an  interpreter,  before  decrementing  the  same  for  the
                            current  interpreter.  This leaves the overall reference count intact
                            without causing  Tcl  to  close  it  when  it  is  removed  from  the
                            interpreter  structures.  At  this point the channel is effectively a
                            globally-owned  part  of  the  system   not   associated   with   any
                            interpreter.

                            The complementary result type then runs this sequence in reverse. And
                            if the channel is never returned to Tcl either the  function  or  the
                            system  it  is a part of have to unregister the global reference when
                            they are done with it.

                     int    The function takes an argument of type int.  The Tcl argument must be
                            convertible to Int, an error is thrown otherwise.

                     int > 0

                     int >= 0

                     int < 0

                     int <= 0

                     int > 1

                     int >= 1

                     int < 1

                     int <= 1
                            These  are  variants  of int above, restricting the argument value to
                            the shown relation. An error is thrown for Tcl arguments  outside  of
                            the specified range.  Note: This is not a general range specification
                            syntax. Only the listed types exist.

                     long   The function takes an argument of type long int.   The  Tcl  argument
                            must be convertible to Long, an error is thrown otherwise.

                     long > 0

                     long >= 0

                     long < 0

                     long <= 0

                     long > 1

                     long >= 1

                     long < 1

                     long <= 1
                            These  are  variants of long above, restricting the argument value to
                            the shown relation. An error is thrown for Tcl arguments  outside  of
                            the specified range.  Note: This is not a general range specification
                            syntax. Only the listed types exist.

                     wideint
                            The function takes an argument of type Tcl_WideInt.  The Tcl argument
                            must be convertible to WideInt, an error is thrown otherwise.

                     wideint > 0

                     wideint >= 0

                     wideint < 0

                     wideint <= 0

                     wideint > 1

                     wideint >= 1

                     wideint < 1

                     wideint <= 1
                            These  are  variants of wideint above, restricting the argument value
                            to the shown relation. An error is thrown for Tcl  arguments  outside
                            of   the  specified  range.   Note:  This  is  not  a  general  range
                            specification syntax. Only the listed types exist.

                     void*

                     double*

                     float*

                     int*   The function takes an argument of the same-named  C  type.   The  Tcl
                            argument  must  be  convertible  to  ByteArray,  an  error  is thrown
                            otherwise.  The bytes in the ByteArray are then re-interpreted as the
                            raw  representation  of a single C pointer of the given type which is
                            then passed as argument to the function.  In other words, this is for
                            Tcl values somehow holding raw C pointers, i.e. memory addresses.

                            Attention:  These  types are considered DEPRECATED.  It is planned to
                            remove their documentation in release 3.2, and  their  implementation
                            in  release  3.3.   Their deprecation can be undone if good use cases
                            are shown.

       ::critcl::cproc name arguments resulttype
              As documented below, but used when the C function named name already exists.

       ::critcl::cinit text externals
              Appends the C code in text and externals, but only after all  the  other  fragments
              appended  by  the  previously-listed  commands regardless of their placement in the
              Critcl script relative to this command.  Thus, all their content is  visible.   See
              also Runtime Behaviour.

              The  C  code  in text is placed into the body of the initialization function of the
              shared library backing the Critcl script, and is  executed  when  this  library  is
              loaded  into  the  interpreter.   It  has access to the variable Tcl_Interp* interp
              referencing the Tcl interpreter currently being initialized.

              externals is placed outside and just before the initialization function, making  it
              a  good  place  for  any  external symbols required by initialization function, but
              which should not be accessible by any other parts of the C code.

              Calls to this command are cumulative.

              Returns the empty string.

       ::critcl::include path
              This command is a convenient shorthand for

              critcl::code {
                #include <${path}>
              }

   STUBS TABLE MANAGEMENT
       Critcl versions 3 and later provide critcl::api to create  and  manipulate  stubs  tables,
       Tcl's  dynamic  linking mechanism handling the resolution of symbols between C extensions.
       See http://wiki.tcl-lang.org/285 for an introduction, and section  Stubs  Tables  for  the
       details of Critcl's particular variant.

       Importing stubs tables, i.e. APIs, from another extension:

       ::critcl::api import name version
              Adds  the  following  include  directives  into  the  Critcl script and each of its
              companion ".c" files:

              [1]    #include <name/nameDecls.h>

              [2]    #include <name/nameStubLib.h>

              Returns an error if "name"  isn't  in  the  search  path  for  the  compiler.   See
              critcl::cheaders and the critcl application's -I and -includedir options.

              Important:  If  name  is  a  fully-qualified  name  in a non-global namespace, e.g.
              "c::stack", the namespace separators "::" are converted into underscores  ("_")  in
              path names, C code, etc.

              name/nameDecls.h  contains the stubs table type declarations, mapping macros, etc.,
              and may include package-specific  headers.   See  critcl::api  header,  below.   An
              #include  directive  is  added  at  the  beginning of the generated code for Critcl
              script and at the beginning of each of its companion ".c" files.

              name/nameStubLib.h contains the stubs table variable definition and the function to
              initialize  it.   An  #include directive for it is added to the initialization code
              for the Critcl script , along with a call to the initializer function.

              If "name/name.decls" accompanies name/nameDecls.h, it should contain  the  external
              representation  of  the  stubs table used to generate the headers. The file is read
              and the internal representation  of  the  stubs  table  returned  for  use  by  the
              importing package.  Otherwise, the empy string is returned.

              One  possible  use  would  be  the  automatic  generation  of C code calling on the
              functions listed in the imported API.

              When generating a TEA package the names of the imported APIs are  used  to  declare
              configure  options with which the user can declare a non-standard directory for the
              headers of the API. Any API name is  translated  into  a  single  configure  option
              --with-name-include.

       Declaration and export of a stubs table, i.e. API, for the Critcl script:

       ::critcl::api function resulttype name arguments
              Adds  to  the  public API of the Critcl script the signature for the function named
              name and having the signature specified  by  arguments  and  resulttype.   Code  is
              generated  for a ".decls" file, the corresponding public headers, and a stubs table
              usable by critcl::api import.

              arguments is a multidict where each key is an argument type and its  value  is  the
              argument name, and resulttype is a C type.

       ::critcl::api header ?glob pattern...?
              Each  file  matching  a  glob  pattern  is copied into the directory containing the
              generated headers, and an #include directive for it is added to "Decls.h"  for  the
              Critcl script.  Returns an error if a glob pattern matches nothing.

              A  pattern for a relative path is resolved relative to the directory containing the
              Critcl script.

       ::critcl::api extheader ?file...?
              Like ::critcl::api header, but each file should exist in the  external  development
              environment.   An  #include  directive  is  added  to "fooDecls.h", but file is not
              copied to the package header directory. file is not a glob pattern as Critcl has no
              context, i.e directory, in which to expand such patterns.

       As  with  the headers for an imported API, an #include directive is added to the generated
       code for the Critcl script and to each companion ".c" file.

       In "compile & run" mode the generated header files and any companion headers are placed in
       the  Result  Cache  subdirectory  for  the  Critcl  script. This directory is added to the
       include search path of any other package importing this  API  and  and  building  in  mode
       "compile & run".

       In  "generate package" mode -includedir specifies the subdirectory in the package to place
       the generated headers in. This directory is added to the search paths  for  header  files,
       ensuring  that  a package importing an API finds it if the package exporting that API used
       the same setting for -includedir.

       In "generate TEA" mode the static scanner recognizes critcl::api header  as  a  source  of
       companion  files.   It  also uses data from calls to critcl::api import to add support for
       --with-foo-include options into the generated "configure(.in)" so that a user may  specify
       custom locations for the headers of any imported API.

   PACKAGE META DATA
       Critcl  versions 3 and later can create TEApot meta-data to be placed into "teapot.txt" in
       a      format      suitable      for       use       by       the       TEApot       tools
       [http://docs.activestate.com/activetcl/8.5/tpm/toc.html].

       In  version  2,  some meta data support was already present through ::critcl::license, but
       this was only used to generate "license.txt".

       ::critcl::license author ?text...?
              Ignored in "compile & run" mode.

              In "generate package" mode provides information about the author of the package and
              the license for the package.

              text  arguments  are concatenated to form the text of the license, which is written
              to "license.terms" in the same directory as "pkgIndex.tcl".  If no text is provided
              the  license  is  read  from  "license.terms"  in  the same directory as the Critcl
              script.

              This information takes  precedence  over  any  information  specified  through  the
              generic  API  ::critcl::meta.   It  is  additionally placed into the meta data file
              "teapot.txt" under the keys as::author and license.

       ::critcl::summary text
              Ignored in "compile & run" mode.

              In "generate package" mode places a short, preferably one-line description  of  the
              package  into  the  meta  data  file  "teapot.txt"  under  the  key  summary.  This
              information takes precedence over information specified  through  the  generic  API
              ::critcl::meta.

       ::critcl::description text
              Ignored in "compile & run" mode.

              In "generate package" mode places a longer description of the package into the meta
              data file "teapot.txt", under the key description.   The  data  specified  by  this
              command  takes  precedence  over  any information specified through the generic API
              ::critcl::meta.

       ::critcl::subject ?key...?
              Ignored in "compile & run" mode.

              In "generate package" mode places each key into the meta  data  file  "teapot.txt",
              under  the  key  subject.   This  information takes precedence over any information
              specified through the generic API ::critcl::meta.

              Calls to this command are cumulative.

       ::critcl::meta key ?word...?
              Provides arbitrary meta data outside of the following  reserved  keys:  as::author,
              as::build::date,  description,  license,  name, platform, require subject, summary,
              and version, Its behaviour is like ::critcl::subject in that it treats all keys  as
              list of words, with each call providing one or more words for the key, and multiple
              calls extending the data for an existing key, if not reserved.

              While it is possible to declare information for one of the reserved keys with  this
              command such data is ignored when the final meta data is assembled and written.

              Use   the   commands  ::critcl::license,  ::critcl::summary,  ::critcl::description
              ::critcl::subject, package require, and package provide to  declare  data  for  the
              reserved keys.

              The information for the reserved keys as::build::date and platform is automatically
              generated by critcl itself.

       ::critcl::meta? key
              Returns the value in the metadata associated with key.

              Used primarily to retrieve the name of the package  from  within  utility  packages
              having  to  adapt C code templates to their environment. For example, critcl::class
              uses does this.

       ::critcl::buildrequirement script
              Provides control over the capturing of dependencies declared via  package  require.
              script  is  evaluated  and  any  dependencies declared within are ignored, i.e. not
              recorded in the meta data.

   CONTROL & INTERFACE
       These commands control the details of  compilation  and  linking  a  Critcl  script.   The
       information  is  used only to compile/link the object for the Critcl script.  For example,
       information for "FOO.tcl" is kept separate from information for "BAR.tcl".

       ::critcl::cheaders ?arg...?
              Provides additional header locations.

              Each argument is a glob pattern.  If an argument begins with - it is an argument to
              the  compiler.  Otherwise the parent directory of each matching path is a directory
              to be searched for header files.  Returns an error if a pattern matches  no  files.
              A  pattern for a relative path is resolved relative to the directory containing the
              Critcl script.

              #include lines are not automatically generated  for  matching  header  files.   Use
              critcl::include or critcl::ccode as necessary to add them.

              Calls to this command are cumulative.

       ::critcl::csources ?glob pattern...?
              Matching  paths  become  inputs to the compilation of the current object along with
              the sources for the current Critcl script.  Returns an error if no  paths  match  a
              pattern.   A  pattern  for  a  relative  path is resolved relative to the directory
              containing the Critcl script.

              Calls to this command are cumulative.

       ::critcl::clibraries ?glob pattern...?
              provides the link step with additional libraries and  library  locations.   A  glob
              pattern  that  begins  with  -  is  added  as an argument to the linker.  Otherwise
              matching files are linked into the shared library.  Returns an error  if  no  paths
              match  a  pattern.   A  pattern  for  a  relative  path is resolved relative to the
              directory containing the Critcl script.

              Calls to this command are cumulative.

       ::critcl::source glob pattern
              Evaluates as scripts the files matching each glob pattern.   Returns  an  error  if
              there are no matching files.  A pattern for a relative path is resolved relative to
              the directory containing the Critcl script.

       ::critcl::tsources glob pattern...
              Provides the information about additional Tcl  script  files  to  source  when  the
              shared library is loaded.

              Matching paths are made available to the generated shared library when it is loaded
              for the current Critcl script.  Returns an error if a pattern matches no files.   A
              pattern  for  a  relative path is resolved relative to the directory containing the
              Critcl script.

              Calls to this command are cumulative.

              After the shared library has been loaded, the declared files  are  sourced  in  the
              same order that they were provided as arguments.

       ::critcl::owns glob pattern...
              Ignored  in "compile and run" and "generate package" modes.  In "generate TEA" mode
              each file matching a glob pattern is a file to be included in the TEA extension but
              that  could not be ascertained as such from previous commands like critcl::csources
              and critcl::tsources, either because of they were specified dynamically or  because
              they were directly sourced.

       ::critcl::cflags ?arg...?

              Each arg is an argument to the compiler.

              Calls to this command are cumulative.

       ::critcl::ldflags ?arg...?

              Each arg is an argument to the linker.

              Calls to this command are cumulative.

       ::critcl::framework ?arg...?
              Each arg is the name of a framework to link on MacOS X.  This command is ignored if
              OS X is not the target so that frameworks can be specified unconditionally.

              Calls to this command are cumulative.

       ::critcl::tcl version
              Specifies the minimum version of the Tcl runtime to compile and  link  the  package
              for.  The default is 8.4.

       ::critcl::tk
              Arranges to include the Tk headers and link to the Tk stubs.

       ::critcl::preload lib...
              Arranges for the external shared library lib to be loaded before the shared library
              for the Critcl script is loaded.

              Calls to this command are cumulative.

              Each library FOO is searched for in the directories  listed  below,  in  the  order
              listed.  The search stops at the first existing path.  Additional notes:

              •      platform is the placeholder for the target platform of the package.

              •      The extension ".so" is the placeholder for whatever actual extension is used
                     by the target platform for its shared libraries.

              •      The search is relative to the current working directory.

              And now the paths, depending on the exact form of the library name:

              FOO

                     [1]    FOO.so

                     [2]    FOO/FOO.so

                     [3]    FOO/platform/FOO.so

              PATH/FOO
                     The exact set searched depends on the existence of directory "PATH/FOO".  If
                     it exists, critcl searches

                     [1]    FOO.so

                     [2]    PATH/FOO/FOO.so

                     [3]    PATH/FOO/platform/FOO.so

                     Otherwise it searches

                     [1]    FOO.so

                     [2]    PATH/FOO.so

                     [3]    PATH/platform/FOO.so

                     instead.

              /PATH/FOO
                     Even  when  specifying  FOO with an absolute path the first path searched is
                     relative to the current working directory.

                     [1]    FOO.so

                     [2]    /PATH/FOO.so

                     [3]    /PATH/platform/FOO.so

              For developers who want to  understand  or  modify  the  internals  of  the  critcl
              package, Preloading functionality explains how preloading is implemented.

       ::critcl::debug area...
              Specifies  what  debugging features to activate. Internally each area is translated
              into  area-specific  flags  for  the  compiler  which  are  then  handed  over   to
              critcl::cflags.

              memory Specifies Tcl memory debugging.

              symbols
                     Specifies  compilation  and  linking  with  debugging  symbols  for use by a
                     debugger or other tool.

              all    Specifies all available debugging.

   INTROSPECTION
       The following commands control compilation and linking.

       ::critcl::check ?label? text
              Returns a true if the C code in text compiles  sucessfully,  and  false  otherwise.
              Used  to check for availability of features in the build environment.  If provided,
              label is used to uniquely mark the results in the generated log.

       ::critcl::checklink ?label? text
              Like critcl::check but also links the compiled objects, returning true if the  link
              is  successful  and  false otherwise.  If specified, label is used to uniquely mark
              the results in the generated log.

       ::critcl::msg ?-nonewline? msg
              Scripts using critcl::check and critcl::checklink can use this  command  to  report
              results.  Does nothing in compile & run mode.  Tools like the CriTcl Aplication may
              redefine this command to  implement  their  own  message  reporting.  For  example,
              critcl::app and any packages built on it print messages to stdout.

       ::critcl::print ?-nonewline? ?chan? msg
              Used  by the Critcl internals to report activity.  By default, effectively the same
              thing as ::puts.  Tools directly using either the  Critcl  package  or  the  Critcl
              application  package  may  redefine  this  procedure  to implement their own output
              functionality.

              For       example,       the        newest        revisions        of        Kettle
              [https://chiselapp.com/user/andreas_kupries/repository/Kettle/index]  use  this  to
              highlight build warnings.

       ::critcl::compiled
              Returns true if the current Critcl script is already compiled and false otherwise.

              Enables a Critcl script used as its own Tcl companion file  (see  critcl::tsources)
              to  distinguish  between  being  sourced  for compilation in compile & run mode and
              being sourced from either the result of generate package mode or  during  the  load
              phase of compile & run mode.  The result is false in the first case and true in the
              later two cases.

       ::critcl::compiling
              Returns true if a working C compiler is available and false otherwise.

       ::critcl::done
              Returns true when Critcl script has been built and false  otherwise.   Only  useful
              from  within  a  Critcl  script.   Enables  the  Tcl  parts  of  a Critcl script to
              distinguish between prebuilt package mode and compile & run mode.

              See also Modes Of Operation/Use.

       ::critcl::failed
              Returns true if the Critcl script could not be built, and false otherwise.   Forces
              the  building  of  the package if it hasn't already been done, but not its loading.
              Thus, a Critcl script can check itself for availability of the compiled components.
              Only useful from within a Critcl script.

       ::critcl::load
              Like  critcl::failed except that it also forces the loading of the generated shared
              library, and that it returns true on success and false on failure.  Thus, a  Critcl
              script  can  check itself for availability of the compiled components.  Only useful
              from within a Critcl script.

   BUILD MANAGEMENT
       The following command manages  global  settings,  i.e.  configuration  options  which  are
       independent of any Critcl script.

       This  command  should  not  be needed to write a Critcl script. It is a management command
       which is only useful to the CriTcl Application or similar tools.

       ::critcl::config option ?val?
              Sets and returns the following global configuration options:

              force bool
                     When false (the default), the C files are not built if  there  is  a  cached
                     shared library.

              lines bool
                     When  true (the default), #line directives are embedded into the generated C
                     code.

                     This facility requires  the  use  of  a  tclsh  that  provides  info  frame.
                     Otherwise,  no #line directives are emitted. The command is supported by Tcl
                     8.5 and higher. It is also  supported  by  Tcl  8.4  provided  that  it  was
                     compiled  with  the define -DTCL_TIP280. An example of such is ActiveState's
                     ActiveTcl.

                     Developers of higher-level packages generating  their  own  C  code,  either
                     directly  or  indirectly  through critcl, should also read section Advanced:
                     Location management to  see  how  critcl  helps  them  in  generating  their
                     directives.   Examples  of  such  packages  come  with  critcl  itself.  See
                     critcl::iassoc and critcl::class.

              trace bool
                     When false (the default), no code tracing the  entry  and  exit  of  Critcl-
                     backed  commands  in  the Critcl script is inserted.  Insertion of such code
                     implicitly activates the tracing facility in general.  See critcl::cutil.

              I path A single global include path to use for all files. Not set by default.

              combine enum

                     dynamic (the default)
                            Object files have the suffix _pic.

                     static Object files have the suffix _stub.

                     standalone
                            Object files have no suffix, and the generated C files  are  compiled
                            without  using  Tcl/Tk  stubs. The result are object files usable for
                            static linking into a big shell.

              language string

              keepsrc bool
                     When false (the default), the generated ".c" files  are  deleted  after  the
                     ".o" files have been built.

              outdir directory
                     The  directory  where to place a generated shared library. By default, it is
                     placed into the Result Cache.

   RESULT CACHE MANAGEMENT
       The following commands control the Result Cache.  These commands are not needed to  simply
       write a Critcl script.

       ::critcl::cache ?path?
              Sets and returns the path to the directory for the package's result cache.

              The  default  location  is  "~/.critcl/[platform::generic]"  and  usually  does not
              require any changes.

       ::critcl::clean_cache ?pattern...?
              Cleans the result cache, i.e. removes any and all files and directories in  it.  If
              one  or  more  patterns  are specified then only the files and directories matching
              them are removed.

   BUILD CONFIGURATION
       The following commands manage the build configuration, i.e. the  per-platform  information
       about compilers, linkers, and their commandline options.  These commands are not needed to
       simply write a Critcl script.

       ::critcl::readconfig path
              Reads the build configuration file at path and configures  the  package  using  the
              information for the target platform.

       ::critcl::showconfig ?chan?
              Converts  the  active  build configuration into a human-readable string and returns
              it, or if chan is provided prints the result to that channel.

       ::critcl::showallconfig ?chan?
              Converts the set of all known build configurations from the currently active  build
              configuration  file  last set with critcl::readconfig into a string and returns it,
              or if chan is provided, prints it to that channel.

       ::critcl::chooseconfig target ?nomatcherr?
              Matches target against all known targets,  returning  a  list  containing  all  the
              matching  ones.  This  search  is  first  done on an exact basis, and then via glob
              matching. If no known target matches the argument the default is to return an empty
              list.  However,  if  the boolean nomatcherr is specified and set an error is thrown
              using critcl::error instead.

       ::critcl::setconfig target
              Configures the package to use the settings of target.

   TOOL API
       The following commands provide tools like CriTcl Application or similar with deeper access
       to  the  package's  internals.   These  commands  are  not needed to simply write a Critcl
       script.

       ::critcl::actualtarget
              Returns the platform identifier for the target platform, i.e. the platform to build
              for.  Unlike  ::critcl::targetplatform  this  is  the  true target, with any cross-
              compilation information resolved.

       ::critcl::buildforpackage ?flag?
              Signals whether the next file is to be built for inclusion into a package.  If  not
              specified  the  flag defaults to true, i.e. building for a package. This disables a
              number of things in the backend, namely the linking of  that  file  into  a  shared
              library  and the loading of that library. It is expected that the build results are
              later wrapped into a larger collection.

       ::critcl::cnothingtodo file
              Checks whether there is anything to build for file.

       ::critcl::cresults ?file?
              Returns information about building file, or info script If file  is  not  provided.
              The result in question is a dictionary containing the following items:

              clibraries
                     A list of external shared libraries and/or directories needed to link file.

              ldflags
                     A list of linker flags needed to link file.

              license
                     The text of the license for the package file is located in.

              mintcl The  minimum  version  of  Tcl  required  by  the  package file is in to run
                     successfully. A proper Tcl version number.

              objects
                     A list of object files to link into file.

              preload
                     A list of libraries to be preloaded in order to  sucessfully  load  and  use
                     file.

              tk     true if file requires Tk and false otherwise.

              tsources
                     A  list  of  companion  ".tcl"  files to source in order to load and use the
                     Critcl script file.

              log    The full build log generated by the compiler/linker, including command  line
                     data from critcl, and other things.

              exl    The  raw  build  log  generated  by the compiler/linker. Contains the output
                     generated by the invoked applications.

       ::critcl::crosscheck
              Determines whether the package is configured for  cross-compilation  and  prints  a
              message to the standard error channel if so.

       ::critcl::error msg
              Used  to  report  internal  errors.  The  default implementation simply returns the
              error.  Tools like the CriTcl Application are allowed to redefine this procedure to
              perform  their  own  way  of  error reporting. There is one constraint they are not
              allowed to change: The procedure must not return to the caller.

       ::critcl::knowntargets
              Returns a list of the identifiers of all targets found during the  last  invocation
              of critcl::readconfig.

       ::critcl::sharedlibext
              Returns the file extension for shared libraries on the target platform.

       ::critcl::targetconfig
              Returns  the identifier of the target to build for, as specified by either the user
              or the system.

       ::critcl::buildplatform
              Returns the identifier of the build platform, i.e. where the package is running on.

       ::critcl::targetplatform
              Returns the identifier of the target platform, i.e. the platform to compile for. In
              contrast  to  ::critcl::actualtarget  this  may  be the name of a cross-compilation
              target.

       ::critcl::cobjects ?glob pattern...?
              Like ::critcl::clibraries, but instead of matching  libraries,  each  glob  pattern
              matches  object  files  to  be  linked into the shared object (at compile time, not
              runtime). If a glob pattern matches nothing an error is returned.   Not  listed  in
              Control & Interface because it is of no use to package writers. Only tools like the
              CriTcl Application need it.

              A pattern for a relative path is resolved relative to the directory containing  the
              Critcl script.

              Calls to this command are cumulative.

       ::critcl::scan path
              The  main  entry point to Critcl's static code scanner.  Used by tools to implement
              processing modes like the assembly of  a  directory  hierarchy  containing  a  TEA-
              lookalike buildystem, etc.

              Scans path and returns a dictionary containing the following items:

              version
                     Package version.

              org    Author(ing organization).

              files  List of the companion files, relative to the directory of the input file.

       ::critcl::name2c name
              Given  the  Tcl-level  identifier  name,  returns  a  list containing the following
              details of its conversion to C:

              •      Tcl namespace prefix

              •      C namespace prefix

              •      Tcl base name

              •      C base name

       For use by utilities that provide Tcl commands without  going  through  standard  commands
       like critcl::ccommand or critcl::cproc.  critcl::class does this.

   ADVANCED: EMBEDDED C CODE
       For advanced use, the following commands used by critcl::cproc itself are exposed.

       ::critcl::argnames arguments
              Given  an  argument  declaration as documented for critcl::cproc, returns a list of
              the corresponding user-visible names.

       ::critcl::argcnames arguments
              Given an argument declaration as documented for critcl::cproc, returns  a  list  of
              the  corresponding  C variable names for the user-visible names. The names returned
              here  match  the  names  used  in   the   declarations   and   code   returned   by
              ::critcl::argvardecls and ::critcl::argconversion.

       ::critcl::argcsignature arguments
              Given  an  argument  declaration as documented for critcl::cproc, returns a list of
              the corresponding C parameter declarations.

       ::critcl::argvardecls arguments
              Given an argument declaration as documented for critcl::cproc, returns  a  list  of
              the  corresponding  C  variable declarations.  The names used in these declarations
              match the names returned by ::critcl::argcnames.

       ::critcl::argconversion arguments ?n?
              Given an argument declaration as documented for critcl::cproc, returns a list of  C
              code  fragments converting the user visible arguments found in the declaration from
              Tcl_Obj* to C types. The names used in these statements match the names returned by
              ::critcl::argcnames.

              The  generated  code  assumes  that the procedure arguments start at index n of the
              objv array.  The default is 1.

       ::critcl::argoptional arguments
              Given an argument declaration as documented for critcl::cproc, returns  a  list  of
              boolean  values  indicating  which arguments are optional (true), and which are not
              (false).

       ::critcl::argdefaults arguments
              Given an argument declaration as  documented  for  critcl::cproc,  returns  a  list
              containing the default values for all optional arguments.

       ::critcl::argsupport arguments
              Given  an argument declaration as documented for critcl::cproc, returns a list of C
              code fragments needed to define the necessary supporting types.

   CUSTOM BUILD CONFIGURATION
       This package provides one command for the management of package-specific, i.e.  developer-
       specified custom build configuration options.

       ::critcl::userconfig define name description type ?default?
              This  command defines custom build configuration option, with description, type and
              optional default value.

              The type can be either bool, or a list of values.

              [1]    For bool the default value, if specified, must be a boolean. If  it  is  not
                     specified it defaults to true.

              [2]    For  a list of values the default value, if specified, must be a value found
                     in this list. If it is not specified it defaults to the first value  of  the
                     list.

       The  description  serves  as  in-code  documentation  of  the meaning of the option and is
       otherwise ignored. When generating a TEA wrapper the description is used for the configure
       option derived from the option declared by the command.

       A  boolean  option  FOO  are translated into a pair of configure options, --enable-FOO and
       --disable-FOO, whereas an option whose type is a list  of  values  is  translated  into  a
       single configure option --with-FOO.

       ::critcl::userconfig query name
              This  command  queries  the  database  of custom build configuration option for the
              current ".critcl" file and returns the chosen value.  This may be the default if no
              value was set via ::critcl::userconfig set.

              It  is at this point that definitions and set values are brought together, with the
              latter validated against the definition.

       ::critcl::userconfig set name value
              This command is for use by a tool, like the critcl application, to  specify  values
              for custom build configuration options.

              At the time this command is used only the association between option name and value
              is recorded, and nothing else is done. This behaviour is necessary  as  the  system
              may not know if an option of the specified name exists when the command is invoked,
              nor its type.

              Any and all validation is defered to when the value of an option is asked  for  via
              ::critcl::userconfig query.

              This  means that it is possible to set values for any option we like, and the value
              will take effect only if such an option is both defined and used later on.

   ADVANCED: LOCATION MANAGEMENT
       First a small introduction for whose asking themselves ´what is location management' ?

       By default critcl embeds #line directives into the generated C code so  that  any  errors,
       warnings  and notes found by the C compiler during compilation will refer to the ".critcl"
       file the faulty code comes from, instead of the generated ".c" file.

       This facility requires the use of a tclsh that provides info frame.  Otherwise,  no  #line
       directives  are  emitted.  The  command  is  supported  by  Tcl 8.5 and higher. It is also
       supported by Tcl 8.4 provided that it  was  compiled  with  the  define  -DTCL_TIP280.  An
       example of such is ActiveState's ActiveTcl.

       Most  users  will not care about this feature beyond simply wanting it to work and getting
       proper code references when reading compiler output.

       Developers of higher-level packages generating their own C code however should care  about
       this,  to  ensure that their generated code contains proper references as well. Especially
       as this is key to separating bugs concerning code generated by the package itself and  bug
       in the user's code going into the package, if any.

       Examples  of  such  packages  come  with critcl itself, see the implementation of packages
       critcl::iassoc and critcl::class.

       To help such developers eight commands are provided to manage such  location  information.
       These are listed below.

       A  main  concept  is that they all operate on a single stored location, setting, returning
       and clearing it.  Note that this location information is  completely  independent  of  the
       generation of #line directives within critcl itself.

       ::critcl::at::caller
              This  command stores the location of the caller of the current procedure as a tuple
              of file name and linenumber. Any previously stored location  is  overwritten.   The
              result of the command is the empty string.

       ::critcl::at::caller offset
              As above, the stored line number is modified by the specified offset. In essence an
              implicit call of critcl::at::incr.

       ::critcl::at::caller offset level
              As above, but the level the location information is taken from is modified as well.
              Level 0 is the caller, -1 its caller, etc.

       ::critcl::at::here
              This  command  stores  the  current location in the current procedure as a tuple of
              file name and linenumber. Any  previously  stored  location  is  overwritten.   The
              result of the command is the empty string.

              In terms of ::critcl::at::caller this is equivalent to

                critcl::at::caller 0 1

       ::critcl::at::get*
              This  command  takes  the  stored  location and returns a formatted #line directive
              ready for embedding into some C code. The stored location is left untouched.   Note
              that the directive contains its own closing newline.

              For  proper nesting and use it is recommended that such directives are always added
              to the beginning of a code fragment. This way, should deeper layers add  their  own
              directives these will come before ours and thus be inactive. End result is that the
              outermost layer generating a directive will 'win', i.e. have its directive used. As
              it should be.

       ::critcl::at::get
              This command is like the above, except that it also clears the stored location.

       ::critcl::at::= file line
              This  command  allows  the caller to set the stored location to anything they want,
              outside of critcl's control.  The result of the command is the empty string.

       ::critcl::at::incr n...

       ::critcl::at::incrt str...
              These commands allow the user to modify the line number  of  the  stored  location,
              changing it incrementally. The increment is specified as either a series of integer
              numbers (incr), or a series of strings to consider (incrt). In case of  the  latter
              the delta is the number of lines endings found in the strings.

       ::critcl::at::caller!

       ::critcl::at::caller! offset

       ::critcl::at::caller! offset level

       ::critcl::at::here!
              These  are convenience commands combining caller and here with get. I.e. they store
              the location and immediately return it formatted as proper  #line  directive.  Also
              note that after their use the stored location is cleared.

   ADVANCED: DIVERSIONS
       Diversions are for higher-level packages generating their own C code, to make their use of
       critcl's commands generating Embedded C Code easier.

       These commands normally generate all of their C code for the current ".critcl" file, which
       may not be what is wanted by a higher-level package.

       With a diversion the generator output can be redirected into memory and from there on then
       handled and processed as the caller desires before it is committed to an actual ".c" file.

       An example of such a package comes with critcl itself, see the implementation  of  package
       critcl::class.

       To  help  such  developers  three  commands  are  provided  to  manage  diversions and the
       collection of C code in memory. These are:

       ::critcl::collect_begin
              This command starts the diversion of C code collection into memory.

              The result of the command is the empty string.

              Multiple calls are  allowed,  with  each  call  opening  a  new  nesting  level  of
              diversion.

       ::critcl::collect_end
              This  command  end  the  diversion of C code collection into memory and returns the
              collected C code.

              If multiple levels of diversion are open the call only closes and returns the  data
              from the last level.

              The command will throw an error if no diversion is active, indicating a mismatch in
              the pairing of collect_begin and collect_end.

       ::critcl::collect script
              This is a convenience command which runs the script under diversion and returns the
              collected C code, ensuring the correct pairing of collect_begin and collect_end.

   ADVANCED: FILE GENERATION
       While  file generation is related to the diversions explained in the previous section they
       are not the same.  Even so, like diversions this  feature  is  for  higher-level  packages
       generating their own C code.

       Three  examples of utility packages using this facility comes with critcl itself.  See the
       implementations of packages critcl::literals, critcl::bitmap, and critcl::enum.

       When splitting a package implementation into pieces it is often sensible to have a  number
       of  pure  C  companion  files  containing  low-level  code,  yet  these  files may require
       information about the code in the main ".critcl" file. Such declarations are normally  not
       exportable  and  using  the  stub table support does not make sense, as this is completely
       internal to the package.

       With the file generation command below the main ".critcl" file can generate any number  of
       header files for the C companions to pick up.

       ::critcl::make path contents
              This command creates the file path in a location where the C companion files of the
              package are  able  to  pick  it  up  by  simple  inclusion  of  path  during  their
              compilation, without interfering with the outer system at all.

              The generated file will contain the specified contents.

   ADVANCED: EXTENDING CPROC
       While  the critcl::cproc command understands the most common C types (see section Embedded
       C Code), sometimes this is not enough.

       To get around this limitation the commands in this  section  enable  users  of  critcl  to
       extend  the  set of argument and result types understood by critcl::cproc. In other words,
       they allow them to define their own, custom, types.

       ::critcl::has-resulttype name
              This command tests if the named result-type is known or not.  It returns a  boolean
              value, true if the type is known and false otherwise.

       ::critcl::resulttype name body ?ctype?
              This  command defines the result type name, and associates it with the C code doing
              the conversion (body) from C to Tcl.  The C return type of the associated function,
              also  the C type of the result variable, is ctype. This type defaults to name if it
              is not specified.

              If name is already declared an error is thrown.   Attention!  The  standard  result
              type  void  is  special  as  it has no accompanying result variable. This cannot be
              expressed by this extension command.

              The body's responsibility is the conversion of the  functions  result  into  a  Tcl
              result  and  a  Tcl status. The first has to be set into the interpreter we are in,
              and the second has to be returned.

              The C code of body is guaranteed to be called last in the wrapper around the actual
              implementation   of  the  cproc  in  question  and  has  access  to  the  following
              environment:

              interp A Tcl_Interp* typed C variable referencing the interpreter the result has to
                     be stored into.

              rv     The C variable holding the result to convert, of type ctype.

              As examples here are the definitions of two standard result types:

                  resulttype int {
                Tcl_SetObjResult(interp, Tcl_NewIntObj(rv));
                return TCL_OK;
                  }

                  resulttype ok {
                /* interp result must be set by cproc body */
                return rv;
                  } int

       ::critcl::resulttype name = origname
              This  form  of  the  resulttype  command  declares  name as an alias of result type
              origname, which has to be defined already. If this is not  the  case  an  error  is
              thrown.

       ::critcl::has-argtype name
              This  command  tests  if  the  named  argument-type  is known or not.  It returns a
              boolean value, true if the type is known and false otherwise.

       ::critcl::argtype name body ?ctype? ?ctypefun?
              This command defines the argument type name, and associates  it  with  the  C  code
              doing  the conversion (body) from Tcl to C.  ctype is the C type of the variable to
              hold the conversion result and ctypefun  is  the  type  of  the  function  argument
              itself.   Both  types  default  to  name  if  they  are the empty string or are not
              provided.

              If name is already declared an error is thrown.

              body is a C code fragment that converts a Tcl_Obj* into a C value which  is  stored
              in a helper variable in the underlying function.

              body  is  called  inside  its  own  code  block to isolate local variables, and the
              following items are in scope:

              interp A variable of type Tcl_Interp* which is the interpreter the code is  running
                     in.

              @@     A placeholder for an expression that evaluates to the Tcl_Obj* to convert.

              @A     A  placeholder  for the name of the variable to store the converted argument
                     into.

              As examples, here are the definitions of two standard argument types:

                  argtype int {
                if (Tcl_GetIntFromObj(interp, @@, &@A) != TCL_OK) return TCL_ERROR;
                  }

                  argtype float {
                double t;
                if (Tcl_GetDoubleFromObj(interp, @@, &t) != TCL_OK) return TCL_ERROR;
                @A = (float) t;
                  }

       ::critcl::argtype name = origname
              This form of the argtype command  declares  name  as  an  alias  of  argument  type
              origname,  which  has  to  be  defined already. If this is not the case an error is
              thrown.

       ::critcl::argtypesupport name code ?guard?
              This command defines a C code fragment for the already defined argument  type  name
              which  is  inserted  before  all  functions  using  that  type.  Its purpose is the
              definition of any supporting C types needed by the argument type.  If the  type  is
              used  by  many  functions  the  system  ensures that only the first of the multiple
              insertions of the code fragment is active, and  the  others  disabled.   The  guard
              identifier  is  normally  derived  from  name,  but can also be set explicitly, via
              guard. This latter  allows  different  custom  types  to  share  a  common  support
              structure without having to perform their own guarding.

       ::critcl::argtyperelease name code
              This  command  defines a C code fragment for the already defined argument type name
              which is inserted whenever the worker function of a critcl::cproc  returns  to  the
              shim.  It  is  the  responsibility  of this fragment to unconditionally release any
              resources the critcl::argtype conversion code allocated.  An example  of  this  are
              the  variadic  types  for  the  support  of  the special, variadic args argument to
              critcl::cproc's.  They allocate a C array for the collected arguments which has  to
              be  released  when  the  worker  returns. This command defines the C code for doing
              that.

CONCEPTS

   MODES OF OPERATION/USE
       CriTcl can be used in three different modes of operation, called

       [1]    Compile & Run, and

       [2]    Generate Package

       [3]    Generate TEA Package

       Compile & Run was the original mode and is the default for  critcl_pkg.   Collects  the  C
       fragments from the Critcl script, builds them as needed, and caches the results to improve
       load times later.

       The second mode, Generate Package, was introduced to enable  the  creation  of  (prebuilt)
       deliverable  packages  which  do  not  depend  on  the existence of a build system, i.e. C
       compiler, on the target machine.   This  was  originally  done  through  the  experimental
       Critbind tool, and is now handled by the CriTcl Application, also named critcl.

       Newly  introduced  with  Critcl  version 3 is Generate TEA Package. This mode constructs a
       directory hierarchy from the package which can later be built like a regular TEA  package,
       i.e. using

                .../configure --prefix ...
                make all isntall

       Regarding  the caching of results please read the section about the Result Cache fore more
       details.

   RUNTIME BEHAVIOUR
       The default behaviour of critcl, the package is to defer  the  compilation,  linking,  and
       loading  of  any  C  code  as much as possible, given that this is an expensive operation,
       mainly in the time required.  In other words, the C code embedded into a ".critcl" file is
       built only when the first C command or procedure it provides is invoked.  This part of the
       system uses standard functionality built into the Tcl core, i.e. the  auto_index  variable
       to  map  from  commands  to  scripts  providing  them  and  the unknown command using this
       information when the command is needed.

       A limitation of this behaviour is that it is not possible to just use info commands  check
       for  the  existence  of  a  critcl  defined command. It is also necessary to search in the
       auto_index array, in case it has not been build yet.

       This behaviour can be changed by using the control command critcl::load. When invoked, the
       building,  including loading of the result, is forced. After this command has been invoked
       for a ".critcl" file further definition of C code in this file is not allowed any longer.

   FILE MAPPING
       Each ".critcl" file is backed by a single private ".c" file containing that code, plus the
       boilerplate necessary for its compilation and linking as a single shared library.

       The  Embedded  C  Code  fragments  appear  in  that file in the exact same order they were
       defined in the ".critcl" file, with one exception. The C code provided  via  critcl::cinit
       is put after all other fragments.  In other words all fragments have access to the symbols
       defined by earlier fragments, and the critcl::cinit fragment has access to all, regardless
       of its placement in the ".critcl" file.

       Note:  A  limitation  of  the  current  system is the near impossibility of C level access
       between different critcl-based packages. The issue is not the  necessity  of  writing  and
       sharing  the  proper  extern  statements,  but  that the management (export and import) of
       package-specific stubs-tables is not supported. This means that dependent parts have to be
       forcibly  loaded  before  their user, with all that entails. See section Runtime Behaviour
       for the relevant critcl limitation, and remember that many older platforms do not  support
       the  necessary  resolution  of  symbols, the reason why stubs were invented for Tcl in the
       first place.

   RESULT CACHE
       The compilation of C code is time-consuming critcl not only defers it as much as possible,
       as described in section Runtime Behaviour, but also caches the results.

       This  means  that on the first use of a ".critcl" file "FOO.tcl" the resulting object file
       and shared library are saved into the cache, and on future uses of the same  file  reused,
       i.e.  loaded  directly  without  requiring  compilation,  provided  that  the  contents of
       "FOO.tcl" did not change.

       The change detection is based MD5 hashes. A single hash is  computed  for  each  ".critcl"
       file,  based on hashes for all C code fragments and configuration options, i.e. everything
       which affects the resulting binary.

       As long as the input file doesn't change as per the hash a previously built shared library
       found in the cache is reused, bypassing the compilation and link stages.

       The  command  to  manage  the  cache  are  found in section Result Cache Management.  Note
       however that they are useful  only  to  tools  based  on  the  package,  like  the  CriTcl
       Application. Package writers have no need of them.

       As  a  last  note, the default directory for the cache is chosen based on the chosen build
       target. This means that the cache can be put on  a  shared  (network)  filesystem  without
       having to fear interference between machines of different architectures.

   PRELOADING FUNCTIONALITY
       The  audience of this section are developers wishing to understand and possibly modify the
       internals of critcl package and application.  Package writers can skip this section.

       It explains how the preloading of external libraries is realized.

       Whenever a package declares libraries for preloading critcl will build a supporting shared
       library  providing  a  Tcl  package  named  "preload".   This  package  is not distributed
       separately, but as part of the package requiring the preload functionality.  This  support
       package exports a single Tcl command

       ::preload library
              which  is  invoked  once  per  libraries to preload, with the absolute path of that
              library. The command then loads the library.

              On windows the command will further use the Tcl command  ::critcl::runtime::precopy
              to  copy  the library to the disk, should its path be in a virtual filesystem which
              doesn't directly support the loading of a shared library from it.

       The command ::critcl::runtime::precopy is provided by  the  file  "critcl-rt.tcl"  in  the
       generated  package,  as  is  the  command  ::critcl::runtime::loadlib  which generates the
       ifneeded script expected by Tcl's  package  management.  This  generated  ifneeded  script
       contains the invocations of ::preload.

       The  C code for the supporting library is found in the file "critcl_c/preload.c", which is
       part of the critcl package.

       The  Tcl  code  for  the  supporting  runtime  "critcl-rt.tcl"  is  found  in   the   file
       "runtime.tcl", which is part of the critcl::app package.

   CONFIGURATION INTERNALS
       The  audience of this section are developers wishing to understand and possibly modify the
       internals of critcl package and application.  Package writers can skip this section.

       It explains the syntax of configuration files and the configuration keys used by critcl to
       configure  its  build backend, i.e. how this part of the system accesses compiler, linker,
       etc.

       It  is  recommended  to   open   the   file   containing   the   standard   configurations
       ("path/to/critcl/Config")  in  the  editor of your choice when reading this section of the
       documentation, using it as an extended set of examples going beyond  the  simple  defaults
       shown here.

       First,  the  keys  and  the meaning of their values, plus examples drawn from the standard
       configurations  distributed  with  the  package.   Note  that  when   writing   a   custom
       configuration  it  is  not  necessary to specify all the keys listed below, but only those
       whose default values are wrong or insufficient for the platform in question.

       version
              The command to print the compiler version number.  Defaults to

               gcc -v

       compile
              The command to compile a single C source file to an object file.  Defaults to

               gcc -c -fPIC

       debug_memory
              The list of flags for the compiler to enable memory debugging in Tcl.  Defaults to

               -DTCL_MEM_DEBUG

       debug_symbols
              The list of flags for the compiler to add symbols  to  the  object  files  and  the
              resulting library.  Defaults to

               -g

       include
              The compiler flag to add an include directory.  Defaults to

               -I

       tclstubs
              The compiler flag to set USE_TCL_STUBS.  Defaults to

               -DUSE_TCL_STUBS

       tkstubs
              The compiler flag to set USE_TK_STUBS.  Defaults to

               -DUSE_TK_STUBS

       threadflags
              The list of compiler flags to enable a threaded build.  Defaults to

                  -DUSE_THREAD_ALLOC=1 -D_REENTRANT=1 -D_THREAD_SAFE=1
                  -DHAVE_PTHREAD_ATTR_SETSTACKSIZE=1 -DHAVE_READDIR_R=1
                  -DTCL_THREADS=1

       .

       noassert
              The compiler flag to turn off assertions in Tcl code.  Defaults to

               -DNDEBUG

       optimize
              The compiler flag to specify optimization level.  Defaults to

               -O2

       output The compiler flags to set the output file of a compilation.  Defaults to

               -o [list $outfile]

       NOTE  the  use  of  Tcl commands and variables here.  At the time critcl uses the value of
       this key the value of the referenced variable is substituted into it. The  named  variable
       is the only variable whose value is defined for this substitution.

       object The file extension for object files on the platform.  Defaults to

               .o

       preproc_define
              The  command  to  preprocess  a  C  source  file  without compiling it, but leaving
              #define's in the output. Defaults to

               gcc -E -dM

       preproc_enum
              See preproc_define, except that #define's are not left in the output. Defaults to

               gcc -E

       link   The command to link one or more object files and create a shared library.  Defaults
              to

               gcc -shared

       link_preload
              The  list  of linker flags to use when dependent libraries are pre-loaded. Defaults
              to

               --unresolved-symbols=ignore-in-shared-libs

       strip  The flag to tell the linker to strip symbols from the shared library.  Defaults to

               -Wl,-s

       ldoutput
              Like output, but for the linker.  Defaults to the value of output.

       link_debug
              The list of linker flags needed to build a shared library with symbols. Defaults to
              the  empty  string.  One platform requiring this are all variants of Windows, which
              uses

               -debug:full -debugtype:cv

       link_release
              The list of linker flags needed to build a shared library without symbols,  i.e.  a
              regular  build.  Defaults to the empty string.  One platform requiring this are all
              variants of Windows, which uses

               -release -opt:ref -opt:icf,3 -ws:aggressive

       sharedlibext
              The file extension for shared library files on the platform.  Defaults to

               [info sharedlibextension]

       platform
              The identifier of the platform used in generated packages.  Defaults to

               [platform::generic]

       target The presence of this key marks the configuration as a cross-compilation target  and
              the value is the actual platform identifier of the target.  No default.

       The syntax expected from configuration files is governed by the rules below.  Again, it is
       recommended   to    open    the    file    containing    the    standard    configurations
       ("path/to/critcl/Config")  in  the  editor of your choice when reading this section of the
       documentation, using it as an extended set of examples for the syntax>

       [1]    Each logical line of the configuration file consists of one or more physical lines.
              In  case of the latter the physical lines have to follow each other and all but the
              first must be marked  by  a  trailing  backslash.  This  is  the  same  marker  for
              continuation lines as used by Tcl itself.

       [2]    A  (logical)  line starting with the character "#" (modulo whitespace) is a comment
              which runs until the end of the line, and is otherwise ignored.

       [3]    A (logical) line starting with the word "if" (modulo whitespace) is interpreted  as
              Tcl's if command and executed as such. I.e. this command has to follow Tcl's syntax
              for the command, which may stretch across multiple logical lines. The command  will
              be run in a save interpreter.

       [4]    A (logical) line starting with the word "set" (modulo whitespace) is interpreted as
              Tcl's set command and executed as such. I.e.  this  command  has  to  follow  Tcl's
              syntax  for  the  command,  which  may  stretch  across multiple logical lines. The
              command will be run in a save interpreter.

       [5]    A  line  of  the  form  "platform  variable  value"  defines  a  platform  specific
              configuration  variable  and  value.  The variable has to be the name of one of the
              configuration keys  listed  earlier  in  this  section,  and  the  platform  string
              identifies   the   platform  the  setting  is  for.  All  settings  with  the  same
              identification string form the configuration block for this platform.

       [6]    A line of the special form "platform when expression" marks the  platform  and  all
              the settings in its configuration block as conditional on the expression.

              If  the  build platform is not a prefix of platform, nor vice versa the whole block
              is ignored.  Otherwise the expression is evaluated  via  expr,  in  the  same  safe
              interpreter  used  to  run  any set and if commands found in the configuration file
              (see above).

              If the expression evaluates to true this configuration block is  considered  to  be
              the  build  platform fo the host and chosen as the default configuration.  An large
              example of of this  feature  is  the  handling  of  OS  X  found  in  the  standard
              configuration  file,  where  it  selects  the  architectures  to build based on the
              version of the operating system, the available SDK, etc. I.e.  it  chooses  whether
              the  output  is  universal  or not, and whether it is old-style (ix86 + ppc) versus
              new-style (ix86 32+64) of universality.

       [7]    A line of the special form "platform copy sourceplatform" copies the  configuration
              variables   and   values   currently   defined   in  the  configuration  block  for
              sourceplatform to that of  platform,  overwriting  existing  values,  and  creating
              missing  ones.  Variables  of  platform  not  defined  by by sourceplatform are not
              touched.

              The copied values can be overridden later in the configuration file. Multiple  copy
              lines  may  exist  for  a  platform  and  be  intermixed  with normal configuration
              definitions. Only the last definition of a variable is used.

       [8]    At last, a line of the  form  "variable  value"  defines  a  default  configuration
              variable and value.

   STUBS TABLES This section is for developers of extensions not based on critcl, yet
       also  wishing to interface with stubs as they are understood and used by critcl, either by
       exporting their own stubs table to a critcl-based extension, or importing a stubs table of
       a critcl-based extension into their own.

       To this end we describe the stubs table information of a package foo.

       [1]    Note  that the differences in the capitalization of "foo", "Foo", "FOO", etc. below
              demonstrate how to capitalize the actual package name in each context.

       [2]    All relevant files must be available in a sub-directory "foo" which can be found on
              the include search paths.

       [3]    The  above  directory  may  contain a file "foo.decls". If present it is assumed to
              contain the external representation of the stubs table the headers mentioned in the
              following items are based on.

              critcl is able to use such a file to give the importing package programmatic access
              to the imported API, for automatic code generation and the like.

       [4]    The above directory must contain a header file "fooDecls.h". This file declares the
              exported  API.   It is used by both exporting and importing packages. It is usually
              generated and must contain (in the order specified):

              [1]    the declarations of the exported, i.e. public, functions of foo,

              [2]    the declaration of structure "FooStubs" for the stub table,

              [3]    the C  preprocessor  macros  which  route  the  invocations  of  the  public
                     functions through the stubs table.

                     These  macros  must  be  defined  if,  and only if, the C preprocessor macro
                     USE_FOO_STUBS is defined. Package foo does not define this macro, as  it  is
                     allowed  to  use  the  exported  functions  directly. All importing packages
                     however must define this macro, to ensure that they do not use  any  of  the
                     exported functions directly, but only through the stubs table.

              [4]    If the exported functions need additional types for their proper declaration
                     then these types should be put into a separate  header  file  (of  arbitrary
                     name)  and  "fooDecls.h" should contain an #include directive to this header
                     at the top.

       A very reduced, yet also complete example, from a  package  for  low-level  random  number
       generator functions can be found at the end of this section.

       [5]    The  above  directory  must contain a header file "fooStubLib.h". This file defines
              everything needed to use the API of foo. Consequently it is used only by  importing
              packages. It is usually generated and must contain (in the order specified):

              [1]    An #include directive for "tcl.h", with USE_TCL_STUBS surely defined.

              [2]    An #include directive for "fooDecls.h", with USE_FOO_STUBS surely defined.

              [3]    A definition of the stubs table variable, i.e.

                     const FooStubs* fooStubsPtr;

              [4]    A definition of the stubs initializer function, like

                     char *
                     Foo_InitStubs(Tcl_Interp *interp, CONST char *version, int exact)
                     {
                         /*
                          * Boiler plate C code initalizing the stubs table variable,
                          * i.e. "fooStubsPtr".
                          */

                         CONST char *actualVersion;

                         actualVersion = Tcl_PkgRequireEx(interp, "foo", version,
                                    exact, (ClientData *) &fooStubsPtr);

                         if (!actualVersion) {
                       return NULL;
                         }

                         if (!fooStubsPtr) {
                       Tcl_SetResult(interp,
                                "This implementation of Foo does not support stubs",
                                TCL_STATIC);
                       return NULL;
                         }

                         return (char*) actualVersion;
                     }

              This  header file must be included by an importing package exactly once, so that it
              contains only one definition of both stubs table and stubs initializer function.

              The importing package's initialization function must further  contain  a  statement
              like

              if (!Foo_InitStubs (ip, "1", 0)) {
                  return TCL_ERROR;
              }

              which invokes foo's stubs initializer function to set the local stub table up.

              For a complete example of such a header file see below, at the end of this section.

       [6]    The  last  item  above,  about  "fooStubLib.h" differs from the regular stub stable
              system used by Tcl. The regular system assumes that a static library "libfoostub.a"
              was installed by package foo, and links it.

              IMVHO  critcl's  approach  is  simpler,  using  only header files found in a single
              location, vs.  header  files  and  static  library  found  in  multiple,  different
              locations.

              A second simplification is that we avoid having to extend critcl's compiler backend
              with settings for the creation of static libraries.

       Below is a complete set of example header files,  reduced,  yet  still  complete,  from  a
       package for low-level random number generator functions:

       "rngDecls.h":

              #ifndef rng_DECLS_H
              #define rng_DECLS_H

              #include <tcl.h>

              /*
               * Exported function declarations:
               */

              /* 0 */
              EXTERN void rng_bernoulli(double p, int*v);

              typedef struct RngStubs {
                  int magic;
                  const struct RngStubHooks *hooks;

                  void (*rng_bernoulli) (double p, int*v); /* 0 */
              } RngStubs;

              #ifdef __cplusplus
              extern "C" {
              #endif
              extern const RngStubs *rngStubsPtr;
              #ifdef __cplusplus
              }
              #endif

              #if defined(USE_RNG_STUBS)

              /*
               * Inline function declarations:
               */

              #define rng_bernoulli  (rngStubsPtr->rng_bernoulli) /* 0 */

              #endif /* defined(USE_RNG_STUBS) */
              #endif /* rng_DECLS_H */

       "rngStubLib.h":

              /*
               * rngStubLib.c --
               *
               * Stub object that will be statically linked into extensions that wish
               * to access rng.
               */

              #ifndef USE_TCL_STUBS
              #define USE_TCL_STUBS
              #endif
              #undef  USE_TCL_STUB_PROCS

              #include <tcl.h>

              #ifndef USE_RNG_STUBS
              #define USE_RNG_STUBS
              #endif
              #undef  USE_RNG_STUB_PROCS

              #include "rngDecls.h"

              /*
               * Ensure that Rng_InitStubs is built as an exported symbol.  The other stub
               * functions should be built as non-exported symbols.
               */

              #undef  TCL_STORAGE_CLASS
              #define TCL_STORAGE_CLASS DLLEXPORT

              const RngStubs* rngStubsPtr;

              /*
               *----------------------------------------------------------------------
               *
               * Rng_InitStubs --
               *
               * Checks that the correct version of Rng is loaded and that it
               * supports stubs. It then initialises the stub table pointers.
               *
               * Results:
               *  The actual version of Rng that satisfies the request, or
               *  NULL to indicate that an error occurred.
               *
               * Side effects:
               *  Sets the stub table pointers.
               *
               *----------------------------------------------------------------------
               */

              #ifdef Rng_InitStubs
              #undef Rng_InitStubs
              #endif

              char *
              Rng_InitStubs(Tcl_Interp *interp, CONST char *version, int exact)
              {
                  CONST char *actualVersion;

                  actualVersion = Tcl_PkgRequireEx(interp, "rng", version,
                             exact, (ClientData *) &rngStubsPtr);
                  if (!actualVersion) {
                return NULL;
                  }

                  if (!rngStubsPtr) {
                Tcl_SetResult(interp,
                         "This implementation of Rng does not support stubs",
                         TCL_STATIC);
                return NULL;
                  }

                  return (char*) actualVersion;
              }

EXAMPLES

       See section "Embedding C" in Using CriTcl.

       The latest changes are found at the top.

CHANGES FOR VERSION 3.1.18.1

       [1]    Attention: While the overall version (of the bundle) moves to 3.1.18.1 the versions
              of packages critcl and critcl::app are unchanged.

       [2]    Bugfix Generally removed a number of 8.5-isms which slipped into  3.1.18,  breaking
              ability to use it with Tcl 8.4.

       [3]    Bugfix Corrected broken build.tcl uninstall.

       [4]    Bugfix  Package  critcl::class  bumped  to  version  1.1.1.  Fixed partial template
              substitution breaking compilation of the generated code.

CHANGES FOR VERSION 3.1.18

       [1]    Feature (Developer support).  Merged  pull  request  #96  from  sebres/main-direct-
              invoke. Enables direct invokation of the "main.tcl" file for starkits from within a
              dev checkout, i.e. outside of a starkit, or starpack.

       [2]    Feature. Added channel types to the set of builtin argument and result  types.  The
              argument  types  are for simple channel access, access requiring unshared channels,
              and taking the channel fully into the C level, away from Tcl. The result type comes
              in  variants  for  newly  created  channels,  known  channels,  and to return taken
              channels  back  to  Tcl.  The  first  will  register  the  returned  value  in  the
              interpreter, the second assumes that it already is.

       [3]    Bugfix.  Issue #96. Reworked the documentation around the argument type Tcl_Interp*
              to make its special status more visible, explain uses, and call it out from  result
              types where its use will be necessary or at least useful.

       [4]    Feature. Package critcl::class bumped to version 1.1.  Extended with the ability to
              create a C API for classes, and the ability to disable the generation  of  the  Tcl
              API.

       [5]    Bugfix.  Merged  pull  request  #99  from  pooryorick/master.  Fixes  to the target
              directory calculations done by the install code.

       [6]    Merged pull request #94 from andreas-kupries/documentation.  A larger documentation
              cleanup. The main work was done by pooryorick, followed by tweaks done by myself.

       [7]    Extended  the  test  suite with lots of cases based on the examples for the various
              generator packages. IOW the new test cases replicate/encapsulate the  examples  and
              demonstrate that the packages used by the examples generate working code.

       [8]    Bugfix.  Issue  #95.  Changed  the  field critcl_bytes.s to unsigned char* to match
              Tcl's type. Further constified the field to make clear that read-only usage is  the
              common case for it.

       [9]    Bugfix/Feature.  Package  critcl::cutil  bumped  to  version  0.2.   Fixed  missing
              inclusion of header "string.h" in "critcl_alloc.h",  needed  for  memcpy  in  macro
              STREP.  Added macros ALLOC_PLUS and STRDUP.  Moved documentation of STREP... macros
              into proper place (alloc section, not assert).

       [10]   Merged pull request #83 from apnadkarni/vc-fixes.  Removed deprecated -Gs for  MSVC
              builds, and other Windows fixups.

       [11]   Feature.  Package  critcl::iassoc  bumped  to version 1.1.  Refactored internals to
              generate an include header for use by  .c  files.   This  now  matches  what  other
              generator packages do.  The template file is inlined and removed.

       [12]   Merged pull request #82 from gahr/home-symlink Modified tests to handle possibility
              of $HOME a symlink.

       [13]   Merged pull request #81 from gahr/test-not-installed Modified test support to  find
              uninstalled critcl packages when running tests. Handles all but critcl::md5.

       [14]   Merged   pull   request  #85  from  snoe925/issue-84  to  fix  Issue  #84  breaking
              installation on OSX.

       [15]   Merged pull request #87 from apnadkarni/tea-fixes to fix  Issue  #86,  broken  -tea
              option, generating an incomplete package.

       [16]   Feature.   New  package  critcl::callback  providing  C-level  functions  and  data
              structures to manage callbacks from C to Tcl.

       [17]   Feature. Package critcl::literals bumped to version 1.3.  Added mode +list enabling
              the conversion of multiple literals into a list of their strings.

       [18]   Feature.  Package  critcl::enum  bumped to version 1.1.  Added basic mode handling,
              supporting tcl (default) and +list (extension enabling the conversion  of  multiple
              enum values into a list of their strings).

       [19]   Feature.  Package  critcl::emap  bumped  to  version  1.2.   Extended existing mode
              handling with +list extension enabling the conversion of multiple emap values  into
              a list of their strings.

       [20]   Feature.  Extended  the set of available types by applying a few range restrictions
              to the scalar types (int, long, wideint, double, float).

              Example: int > 0 is now a viable type name.

              This is actually more limited than the description might let you believe.

              See the package reference for the details.

CHANGES FOR VERSION 3.1.17

       [1]    Extension: Allow duplicate arg- and  result-type  definitions  if  they  are  fully
              identical.

       [2]    Bugfix.   The   application   mishandled   the   possibility   of   identical-named
              critcl::tsources. Possible because critcl::tsources can  be  in  subdirectories,  a
              structure  which  is  not  retained in the assembled package, causing such files to
              overwrite each other and at least one lost. Fixed by adding a serial number to  the
              file names in the assembled package.

       [3]    Bugfix  in  the static scanner which made it loose requirement information. Further
              added code to generally cleanup results at the end (removal of duplicates, mainly).

       [4]    Bugfix: Fixed issue #76.  Support installation directories which  are  not  in  the
              auto_path.   Without  the patch the installed critcl will not find its own packages
              and fail. Thank you to Simon Bachmann [https://github.com/lupylucke] for the report
              and patch, and then his patience with me to getting to actually apply it.

       [5]    Bugfix: Fixed issue #75.  Extended critcl::include to now take multiple paths.

       [6]    Added new compatibility package lmap84.

       [7]    Fixed typos in various documentation files.

       [8]    Fixed  bug  introduced  by  commit  86f415dd30  (3.1.16 release). The separation of
              critcl::ccode into user and work layers means that location retrieval has to go one
              more level up to find the user location.

       [9]    New  supporting package critcl::cutil. Provides common C level facilities useful to
              packages (assertions, tracing, memory allocation shorthands).

       [10]   Modified package critcl to make use  of  the  new  tracing  facilities  to  provide
              tracing   of   arguments   and   results  for  critcl::ccommand  and  critcl::cproc
              invokations.

       [11]   Modified packages critcl and critcl::class to provide  better  function  names  for
              (class) method tracing.  Bumped package critcl::class to version 1.0.7.

       [12]   Extended  the  support package critcl::literals with limited configurability. It is
              now able to generate code for C-level access to the pool without  Tcl  types  (Mode
              c).   The  previously  existing  functionality is accesssible under mode tcl, which
              also is the default. Both modes can be used together.

       [13]   Extended the support package critcl::emap with limited configurability. It  is  now
              able to generate code for C-level access to the mapping without Tcl types (Mode c).
              The previously existing functionality is accessible under mode tcl, which  also  is
              the default. Both modes can be used together.

CHANGES FOR VERSION 3.1.16

       [1]    New  feature.  Extended critcl::cproc's argument handling to allow arbitrary mixing
              of required and optional arguments.

       [2]    New feature.  Potential Incompatibility.

              Extended critcl::cproc's argument handling to treat an argument args as variadic if
              it is the last argument of the procedure.

       [3]    New feature. Added two introspection commands, critcl::has-argtype and critcl::has-
              resulttype.  These enable a user to test if a specific (named) type  conversion  is
              implemented or not.

       [4]    Added  new result type Tcl_Obj*0, with alias object0. The difference to Tcl_Obj* is
              in the reference counting.

       [5]    Extended the command critcl::argtypesupport  with  new  optional  argument  through
              which   to   explicitly  specify  the  identifier  for  guarding  against  multiple
              definitions.

       [6]    Bugfix: Fixed problem with the implementation of issue  #54  (See  3.1.14).  Always
              create   the   secondary   log  file.  Otherwise  end-of-log  handling  may  break,
              unconditionally assuming its existence.

       [7]    Bugfix: Fixed problem with the internal change to  the  hook  HandleDeclAfterBuild.
              Corrected the forgotten critcl::cconst.

       [8]    Debugging  aid:  Added  comment  holding  the name of the result type when emitting
              result conversions.

       [9]    Bugfix: Fixed issue #60. Unbundled  the  package  directories  containing  multiple
              packages. All directories under "lib/" now contain exactly one package.

       [10]   Bugfix:  Fixed  issue  #62,  a few dict exists commands operating on a fixed string
              instead of a variable.

       [11]   Bugfix: Fixed issue #56. Release builders are reminded to run the tests.

       [12]   Bugfix: Fixed issue #55. For FreeBSD critcl's platform package now  identifies  the
              Kernel   ABI   version.  Initialization  of  the  cache  directory  now  also  uses
              platform::identify for the default path, instead of platform::generic.

       [13]   Bugfix: Fixed issue #58. Simplified the setup and use of md5. Critcl now makes  use
              of  its  own  package  for  md5,  using itself to built it. There is no chicken/egg
              problem with this as the -pkg mode used for this does not use md5. That is  limited
              to mode compile & run.

CHANGES FOR VERSION 3.1.15

       [1]    Fixed version number bogosity with 3.1.14.

CHANGES FOR VERSION 3.1.14

       [1]    Fixed  issue  #36.  Added  message  to target all of the Makefile generated for TEA
              mode. Additionally tweaked other parts of the output to be less noisy.

       [2]    Accepted request implied in issue #54.  Unconditionally  save  the  compiler/linker
              build  log  into key log of the dictionary returned by cresults, and save a copy of
              only the execution output in the new key exl ("execution log").

       [3]    Fixed  issue  #53.  Clarified  the  documentation  of  commands  critcl::load   and
              critcl::failed  with  regard  to their results and the throwing of errors (does not
              happen).

       [4]    Fixed issue #48. Modified mode "compile & run" to allow new declarations in a file,
              after  it  was build, instead of erroring out. The new decls are build when needed.
              Mode "precompile" is unchanged and will continue to trap the situation.

       [5]    Fixed issue #52. Updated the local Tcl/Tk headers to 8.4.20, 8.5.13, and 8.6.4.

       [6]    Fixed issue #45. New feature command critcl::cconst.

       [7]    critcl::util: New command locate to find a file across a set of paths,  and  report
              an  error  when  not  found.  This  is for use in autoconf-like header-searches and
              similar configuration tests.

       [8]    Modified 'AbortWhenCalledAfterBuild' to dump the entire stack (info  frame!).  This
              should make it easier to determine the location of the troubling declaration.

CHANGES FOR VERSION 3.1.13

       [1]    Merged PR #43. Fixed bug loading adjunct Tcl sources.

       [2]    Fixes  in  documentation  and  generated  code of package "critcl::enum". Bumped to
              version 1.0.1.

       [3]    Fixes in documentation of package "critcl::bitmap".

       [4]    New package "critcl::emap". In essence a variant or cross of "critcl::bitmap"  with
              behaviour like "critcl::enum".

       [5]    Merged PR #49. Fixed documentation typo.

       [6]    Merged PR #46. Fixed documentation typo.

       [7]    Merged  PR  #47.  Fixes to test results to match the accumulated code changes. Also
              made portable across Tcl versions (varying error syntax).

       [8]    New predefined argument- and result-type "wideint" mapping to Tcl_WideInt.

       [9]    New predefined argument-type "bytes"  mapping  to  tuple  of  byte-array  data  and
              length.  Note:  The existing "bytearray" type (and its aliases) was left untouched,
              to keep backward compatibility.

       [10]   Modified the internal interface between the Tcl  shim  and  C  function  underneath
              "critcl::cproc"  with  respect  to the handling of optional arguments.  An optional
              argument "X" now induces the use of two C arguments,  "X"  and  "has_X".   The  new
              argument "has_X" is of boolean (int) type. It is set to true when X is set, and set
              to false when X has the default value. C code which  cares  about  knowing  if  the
              argument  is  default  or  not is now able to check that quickly, without having to
              code the default value inside.  NOTE: This change is visible in the output  of  the
              advanced commands "argcnames", "argcsignature", "argvardecls", and "argconversion".

       [11]   Fixed  issue  #50  and  documented  the  availability  of  variable  "interp" (type
              Tcl_Interp*) within "critcl::cinit" C code fragments.  Note  that  while  the  old,
              undocumented name of the variable, "ip", is still usable, it is deprecated. It will
              be fully removed in two releases, i.e. for release 3.1.15.  The variable  name  was
              changed to be consistent with other code environments.

       [12]   Fixed  issue  #51.  Disabled the generation of #line directives for "critcl::config
              lines 0" coming from template files, or code generated with them before  the  final
              value of this setting was known.

       [13]   Fixed  issue  with  handling  of  namespaced  package  names  in  "critcl::iassoc".
              Equivalent to a bug in "critcl::class" fixed for critcl 3.1.1, critcl::class 1.0.1.
              Note: "literals", "enum", "emap", and "bitmap" do not require a fix as they are all
              built on top of "iassoc".

CHANGES FOR VERSION 3.1.12

       [1]    Fixed issue 42. Clear ::errorInfo immediately after startup to prevent  leakage  of
              irrelevant (caught) errors into our script and confusing the usage code.

       [2]    Fixed  issue 40. Keep the order of libraries, and allow duplicates. Both are things
              which are occasionally required for proper linking.

       [3]    Extended the utility package critcl::literals to declare a cproc result-type for  a
              pool.

              Further fixed the generated header to handle multiple inclusion.

              Bumped version to 1.1.

       [4]    Fixed issue with utility package critcl::bitmap.

              Fixed the generated header to handle multiple inclusion.

              Bumped version to 1.0.1.

       [5]    Created  new  utility  package critcl::enum for the quick and easy setup and use of
              mappings between C values and Tcl strings.  Built on top of critcl::literals.

       [6]    Added examples demonstrating the use  of  the  utility  packages  critcl::literals,
              critcl::bitmap, and critcl::enum

CHANGES FOR VERSION 3.1.11

       [1]    Fixed issue #37, via pull request #38, with thanks to Jos DeCoster. Information was
              stored into the v::delproc and v::clientdata arrays using a different key than when
              retrieving the same information, thus failing the latter.

       [2]    New  convenience  command critcl::include for easy inclusion of headers and other C
              files.

       [3]    New command critcl::make to generate a local header of other C  files  for  use  by
              other parts of a package through inclusion.

       [4]    New  utility  package  critcl::literals  for  quick and easy setup of and access to
              pools of fixed Tcl_Obj* strings.  Built on top of critcl::iassoc.

       [5]    New utility package critcl::bitmap for quick and easy setup  and  use  of  mappings
              between C bitsets and Tcl lists whose string elements represent that set.  Built on
              top of critcl::iassoc.

CHANGES FOR VERSION 3.1.10

       [1]    Fixed code version numbering forgotten with 3.1.9.

       [2]    Fixed issue #35. In package mode (-pkg) the object cache directory is unique to the
              process,  thus  we  do  not  need  content-hashing to generate unique file names. A
              simple counter is sufficient and much faster.

              Note that mode "compile & run" is not as blessed and still uses content-hasing with
              md5 to ensure unique file names in its per-user object cache.

       [3]    Fixed  issue  where  the  ccommand  forgot  to  use  its body as input for the UUID
              generation. Thus ignoring changes to it in mode compile & run, and not rebuilding a
              library for changed sources. Bug and fix reported by Peter Spjuth.

CHANGES FOR VERSION 3.1.9

       [1]    Fixed issue #27. Added missing platform definitions for various alternate linux and
              OS X targets.

       [2]    Fixed issue #28. Added missing  -mXX  flags  for  linking  at  the  linux-{32,64}-*
              targets.

       [3]    Fixed  issue  #29. Replaced the use of raw "cheaders" information in the processing
              of "cdefines" with the proper include directives derived from it.

       [4]    Fixed the issue behind rejected pull request #30  by  Andrew  Shadura.  Dynamically
              extract  the  stubs  variable  declarations  from the Tcl header files and generate
              matching variable definitions for use in the package code. The generated code  will
              now  be  always consistent with the headers, even when critcl's own copy of them is
              replaced by system headers.

       [5]    Fixed issue #31. Accepted patch by Andrew Shadura,  with  changes  (comments),  for
              easier  integration of critcl with OS package systems, replacing critcl's copies of
              Tcl headers with their own.

       [6]    Fixed issue  #32.  Merged  pull  request  by  Andrew  Shadura.   Various  typos  in
              documentation and comments.

       [7]    Fixed issue #34. Handle files starting with a dot better.

CHANGES FOR VERSION 3.1.8

       [1]    Fixed  issue with package indices generated for Tcl 8.4.  Join the list of commands
              with semi-colon, not newline.

       [2]    Fixed issue #26 which brought up use-cases I had forgotten to consider while fixing
              bug #21 (see critcl 3.1.6).

CHANGES FOR VERSION 3.1.7

       [1]    Fixed issue #24. Extract and unconditionally display compiler warnings found in the
              build log. Prevents users from missing warnings which, while not causing the  build
              to fail, may still indicate problems.

       [2]    New  feature.  Output hook. All non-messaging user output is now routed through the
              command critcl::print, and users are allowed to override it when using  the  critcl
              application-as-package.

       [3]    New  feature, by Ashok P. Nadkarni. Platform configurations can inherit values from
              configurations defined before them.

CHANGES FOR VERSION 3.1.6

       [1]    Fixed issue #21. While the multi-definition of the stub-table pointer variables was
              ok  with  for  all  the C linkers seen so far C++ linkers did not like this at all.
              Reworked the code to ensure that this set of variables is generated only  once,  in
              the wrapper around all the pieces to assemble.

       [2]    Fixed   issue   #22,   the   handling   of  the  command  identifier  arguments  of
              critcl::ccommand, critcl::cproc, and critcl::cdata. We now properly allow  any  Tcl
              identifier and generate proper internal C identifiers from them.

              As  part  of  this the signature of command critcl::name2c changed. The command now
              delivers a list of four values instead of three. The new value  was  added  at  the
              end.

              Further   adapted   the   implementation   of  package  critcl::class,  a  user  of
              critcl::name2c.  This package is now at version 1.0.6 and requires critcl 3.1.6

              Lastly  fixed  the  mis-handling  of  option  -cname   in   critcl::ccommand,   and
              critcl::cproc.

       [3]    Fixed issue #23.

CHANGES FOR VERSION 3.1.5

       [1]    Fixed  issue  #19.  Made  the regular expression extracting the MSVC version number
              more general to make it work on german  language  systems.  This  may  have  to  be
              revisited in the future, for other Windows locales.

       [2]    Fixed  issue  #20.  Made  option -tea work on windows, at least in a unix emulation
              environment like msys/mingw.

CHANGES FOR VERSION 3.1.4

       [1]    Bugfix in package critcl::class. Generate a dummy field in the class  structure  if
              the class has no class variables. Without this change the structure would be empty,
              and a number of compilers are not able to handle such a type.

       [2]    Fixed a typo which broke the win64 configuration.

       [3]    Fixed issue #16, a typo in the documentation of command critcl::class.

CHANGES FOR VERSION 3.1.3

       [1]    Enhancement. In detail:

       [2]    Added new argument type "pstring", for "Pascal String", a counted  string,  i.e.  a
              combination of string pointer and string length.

       [3]    Added new methods critcl::argtypesupport and ::critcl::argsupport to define and use
              additional supporting code for an argument type, here used by  "pstring"  above  to
              define the necessary structure.

       [4]    Semi-bugfixes  in the packages critcl::class and critcl::iassoc. Pragmas for the AS
              meta data scanner to ensure that the template files are made part of  the  package.
              Versions bumped to 1.0.4 and 1.0.1 respectively.

CHANGES FOR VERSION 3.1.2

       [1]    Enhancement. In detail:

       [2]    Extended  critcl::cproc  to be able to handle optional arguments, in a limited way.
              This is automatically available to critcl::class cproc-based methods as well.

       [3]    Bugfix in lassign emulation for Tcl 8.4.  Properly  set  unused  variables  to  the
              empty string.  Bumped version of emulation package lassign84 to 1.0.1.

CHANGES FOR VERSION 3.1.1

       [1]    Bugfixes all around. In detail:

       [2]    Fixed  the  generation  of  wrong#args  errors  for  critcl::cproc and derived code
              (critcl::class cproc-based methods). Use NULL if there are no arguments,  and  take
              the offset into account.

       [3]    Fixed  the handling of package names by critcl::class. Forgot that they may contain
              namespace separators. Bumped to version 1.0.1.

       [4]    Extended a critcl::class generated error message in instance creation for  clarity.
              Bumped to version 1.0.2.

CHANGES FOR VERSION 3.1

       [1]    Added a new higher-level package critcl::iassoc.

              This  package  simplifies the creation of code associating data with an interpreter
              via Tcl's Tcl_(Get|Set)AssocData() APIs. The user can concentrate on his data while
              all the necessary boilerplate C code to support this is generated by the package.

              This  package  uses several of the new features which were added to the core critcl
              package, see below.

       [2]    Added the higher-level package critcl::class.

              This package simplifies the creation of C level objects  with  class  and  instance
              commands.  The user can write a class definition with class- and instance-variables
              and -methods similar to a TclOO class, with all the necessary boilerplate C code to
              support this generated by the package.

              This  package  uses several of the new features which were added to the core critcl
              package, see below.

       [3]    Extended the API for handling TEApot metadata. Added the command  critcl::meta?  to
              query  the  stored  information.  Main use currently envisioned is retrieval of the
              current package's name by utility commands, for  use  in  constructed  names.  This
              particular  information  is  always available due to the static scan of the package
              file on execution of the first critcl command.

              The new packages critcl::iassoc and critcl::class (see above)  are  users  of  this
              command.

       [4]    Extended the API with a command, critcl::name2c, exposing the process of converting
              a Tcl name into base name, namespace, and C namespace.  This  enables  higher-level
              code generators to generate the same type of C identifiers as critcl itself.

              The new package critcl::class (see above) is a user of this command.

       [5]    Extended the API with a command, critcl::source, executing critcl commands found in
              a separate file in the context of the current file. This enables easier  management
              of  larger  bodies  of  code  as it allows the user to split such up into easier to
              digest smaller chunks without causing the generation of multiple packages.

       [6]    Related to the previous item, extended the API with commands to  divert  collection
              of  generated  C  code  into  memory.  This makes it easier to use the commands for
              embedded C code in higher-level code generators.

              See the section Advanced: Diversions for details of the provided commands.

              The new package critcl::class (see above) is a user of these facilities.

       [7]    Extended the API with commands helping developers with the generation of  proper  C
              #line  directives.  This allows higher-level code generators to generate and insert
              their own directives, ensuring that compile  errors  in  their  code  are  properly
              attributed.

              See the section Advanced: Location management for details of the provided commands.

              The  new  packages  critcl::iassoc and critcl::class (see above) are users of these
              facilities.

       [8]    Extended the API with commands giving users the ability to define  custom  argument
              and result types for ::critcl::cproc.

              See the section Advanced: Extending cproc for details of the provided commands.

CHANGES FOR VERSION 3.0.7

       [1]    Fixed  the  code  generated  by critcl::c++command.  The emitted code handed a non-
              static string table to Tcl_GetIndexFromObj, in violation  of  the  contract,  which
              requires  the  table  to  have  a fixed address. This was a memory smash waiting to
              happen. Thanks to Brian Griffin for alrerting us to the general problem.

CHANGES FOR VERSION 3.0.6

       [1]    Fixed github issue 10. The critcl application now delivers a proper exit  code  (1)
              on build failure, instead of always indicating success (status 0).

       [2]    Fixed  github  issue  13.  Handling  of  bufferoverflowU.lib for release builds was
              inconsistent with  handling  for  debug  builds.  It  is  now  identically  handled
              (conditional) by both cases.

       [3]    Documentation cleanup, mainly in the installation guide, and the README.md shown by
              github

CHANGES FOR VERSION 3.0.5

       [1]    Fixed bug in the new code for  #line  pragmas  triggered  when  specifying  C  code
              without leading whitespace.

       [2]    Extended  the  documentation  to  have  manpages for the license, source retrieval,
              installer, and developer's guides.

CHANGES FOR VERSION 3.0.4

       [1]    Fixed generation of the package's initname when the  incoming  code  is  read  from
              stdin and has no proper path.

       [2]    Fixed  github  issue  11.  Now  using /LIBPATH instead of -L on Windows (libinclude
              configuration setting).

       [3]    Extended critcl to handle -l:path format of -l options.  GNU ld 2.22+ handles  this
              by searching for the path as is. Good when specifying static libraries, as plain -l
              looks for shared libraries in preference over static. critcl  handles  it  now,  as
              older GNU ld's do not understand it, nor the various vendor-specific linkers.

       [4]    Fixed  github  issue #12. Critcl now determines the version of MSVC in use and uses
              it to switch between  various  link  debug  options.  Simplified  the  handling  of
              bufferoverflowU.lib  also,  making use of the same mechanism and collapsing the two
              configurations sections we had back into one.

       [5]    Reworked the insertion of  #line  pragmas  into  the  generated  C  code  to  avoid
              limitations  on  the line number argument imposed by various compilers, and be more
              accurate.

       [6]    Modified argument processing. Option -libdir now also implies -L for its argument.

       [7]    Extended handling of option -show (critcl::showconfig) to  list  the  path  of  the
              configuration  file  the  data  is  coming  from.  Good for debugging configuration
              processing.

       [8]    Extended the build script with targets to regenerate  the  embedded  documentation,
              and diagrams, and to generate a release.

CHANGES FOR VERSION 3.0.3

       [1]    Fixed  github  issues  5 and 8, for the example build.tcl scripts. Working around a
              missing variable ::errorInfo. It should always be present, however there seem to be
              revisions of Tcl around which violate this assumption.

CHANGES FOR VERSION 3.0.2

       [1]    Fixed  issue in compile-and-run mode where commands put into the auto_index are not
              found by Tcl's [unknown] command.

       [2]    Fixed an array key mismatch breaking usage of client data and delete  function  for
              procedure. Reported by Jos DeCoster, with patch.

       [3]    Implemented  a command line option -L, an equivalent of option -I, just for library
              search paths.

       [4]    Fixed github issues 5 and 8. Working around  a  missing  variable  ::errorInfo.  It
              should  always  be  present, however there seem to be revisions of Tcl around which
              violate this assumption.

CHANGES FOR VERSION 3.0.1

       [1]    Bugfixes all around. In detail:

       [2]    Fixed recording  of  Tcl  version  requirements.  Keep  package  name  and  version
              together, unbreaking generated meta data and generated package load command.

       [3]    Fixed the build scripts: When installing, or wrapping for TEA, generate any missing
              directories

       [4]    Modified the build scripts to properly exit the  application  when  the  window  of
              their GUI is closed through the (X) button.

       [5]    Removed an 8.5-ism (open wb) which had slipped into the main build script.

       [6]    Modified  the  example  build  scripts  to  separate  the  output for the different
              examples (and packages) by adding empty lines.

       [7]    stack::c example bugfix: Include API declarations for use in the companion files.

       [8]    Extended the documentation: Noted the need  for  a  working  installation  of  a  C
              compiler.

       [9]    Extended  the Windows target definitions and code to handle the manifest files used
              by  modern  MS  development  environments.  Note  that  this  code   handles   both
              possibilities, environment using manifests, and (old(er)) environments without.

       [10]   Extended  the Windows 64bit target definitions and code to auto-detect the need for
              the helper library "bufferoverflowU.lib"  and  reconfigure  the  compile  and  link
              commands  appropriately.  We  assume  that the library must be linked when present.
              This should be no harm if the library is present, yet not needed. Just superfluous.
              We search for the library in the paths specified by the environment variable LIB.

CHANGES FOR VERSION 3

       [1]    The   command  critcl::platform  was  deprecated  in  version  2.1,  superceded  by
              critcl::targetplatform, yet kept for compatibility. Now it has been removed.

       [2]    The command critcl::compiled was  kept  with  in  version  2.1  with  semantics  in
              contradiction  to  its,  for  compatibility.  This  contradiction has been removed,
              changing the visible semantics of the command to be in line with its name.

       [3]    The change to version 3 became necessary because of the  two  incompatible  visible
              changes above.

       [4]    Extended  the  application package with code handling a new option -tea. Specifying
              this option invokes a special mode where critcl generates a TEA package, i.e. wraps
              the  input  into  a  directory  hierarchy  and  support files which provide it TEA-
              lookalike buildsystem.

              This new option, and -pkg, exclude each other. If both are specified the last  used
              option takes precedence.

              The  generated package directory hierarchy is mostly self-contained, but not fully.
              It requires not only a working installation of Tcl, but also working  installations
              of  the  packages md5 and cmdline. Both of these are provided by the Tcllib bundle.
              Not required, but recommended to have installed are any of the packages  which  can
              accelerate md5's operation, i.e. cryptkit, tcllibc, or Trf.

       [5]    Extended  the  critcl  package with a new command critcl::scan taking the path to a
              ".critcl" file, statically scanning it, and returning license, version, a  list  of
              its  companion files, list of imported APIs, and list of developer-specified custom
              configuration options. This data is the foundation for the TEA  wrapping  described
              above.

              Note that this is a static scan. While the other build modes can (must) execute the
              ".critcl" file and make platform-specific decisions regarding the assembled C code,
              companion  files,  etc.  the  TEA  wrap mode is not in a position to make platform-
              specific decisions. It has to wrap everything which  might  conceivably  be  needed
              when  actually  building.  Hence  the static scan.  This has however its own set of
              problems, namely the inability to figure out any dynamic construction of  companion
              file paths, at least on its own. Thus:

       [6]    Extended the API used by critcl-based packages with the command critcl::owns. While
              this command is ignored by the regular build modes  the  static  scanner  described
              above  takes its arguments as the names of companion files which have to be wrapped
              into the TEA package and could not  be  figured  by  the  scanner  otherwise,  like
              because  of  dynamic  paths  to critcl::tsources, critcl::csources, getting sourced
              directly, or simply being adjunct datafiles.

       [7]    Extended the API used by critcl-based packages with the command critcl::api for the
              management of stubs tables, be it their use, and/or declaration and export.

              Please  see  section Stubs Table Management of the critcl package documentation for
              details.

       [8]    Extended the API used by critcl-based packages with the command  critcl::userconfig
              for the management of developer-specified custom configuration options, be it their
              use and/or declaration.

              Please see section Custom Build Configuration of the critcl  package  documentation
              for details.

       [9]    Extended    the   API   used   by   critcl-based   packages   with   the   commands
              critcl::description,   critcl::summary,    critcl::subject,    critcl::meta,    and
              critcl::buildrequirement  for  the  declaration  of  TEApot meta data for/about the
              package.

              Please see section Package Meta  Data  of  the  critcl  package  documentation  for
              details.

CHANGES FOR VERSION 2.1

       [1]    Fixed  bug  where  critcl::tsources  interpreted  relative paths as relative to the
              current working directory instead of relative  to  the  ".critcl"  file  using  the
              command, as all other commands of this type do.

       [2]    Fixed  internals,  preventing information collected for multiple ".critcl" files to
              leak between them.  Notably,  critcl::tk  is  not  a  global  configuration  option
              anymore.

       [3]    Fixed  the  command critcl::license to be a null-operation in mode "compile & run",
              instead of throwing an error.

       [4]    Fixed the critcl application's interference with the "compile & run"  result  cache
              in  -pkg  mode  by  having  it  use  a  wholly  separate (and by default transient)
              directory for that mode.

       [5]    Fixed bug where changes to a ".critcl" file did not result in a  rebuild  for  mode
              "compile & run". All relevant API commands now ensure UUID changes.

       [6]    Fixed bug in the backend handling of critcl::debug where the companion c-sources of
              a ".critcl" file were not compiled with debug options, although the ".critcl"  file
              was.

       [7]    Fixed  bug  in  critcl::debug which prevented recognition of mode "all" when it was
              not the first argument to the command.

       [8]    Fixed bug in "preload.c" preventing its compilation on non-windows platforms.

       [9]    Fixed long-standing bug in the handling of namespace qualifiers in the command name
              argument  of  critcl::cproc  and  critcl::ccommand. It is now possible to specify a
              fully qualified command name without issues.

       [10]   Extended/reworked critcl::tsources to be the  canonical  way  of  declaring  ".tcl"
              companion files even for mode "compile & run".

       [11]   Extended/reworked  critcl::tsources to allow the use of a ".critcl" file as its own
              Tcl companion file.

       [12]   Extended critcl::framework to internally check for OS X build target, and to ignore
              the declaration if its not.

       [13]   Extended  critcl::failed  to  be  callable  more than once in a ".critcl" file. The
              first call forces the build, if it was not done already, to get the result. Further
              calls return the cached result of the first call.

       [14]   Extended  the  handling  of  environment  variable  CC  in the code determining the
              compiler to use to deal with (i.e. remove) paths to  the  compiler,  compiler  file
              extensions,  and compiler options specified after the compiler itself, leaving only
              the bare name of the compiler.

       [15]   Extended the code handling the search for preloaded libraries to print the paths it
              searched, making debugging of a search failure easier.

       [16]   A  new  command  critcl::tcl  can  be  used to declare the version of Tcl minimally
              needed to build and run the ".critcl" file and package.  Defaults  to  8.4  if  not
              declared.  Extended  critcl  to have the stubs and headers for all of Tcl 8.4, 8.5,
              and 8.6.

       [17]   A new command critcl::load forces the build and load of a ".critcl" file.  This  is
              the official way for overriding critcl's default lazy-build-&-load-on-demand scheme
              for mode "compile & run".

              Note that after using critcl::load / critcl::failed in a ".critcl" file it  is  not
              possible to use critcl commands in that file anymore. Doing so will throw an error.

       [18]   Extended  the  generation  of  '#line'  pragmas to use info frame (if available) to
              provide the C compiler with exact line numbers into  the  ".critcl"  file  for  the
              reporting of warnings and errors.

       [19]   Extended critcl::check with logging to help with debugging build-time checks of the
              environment, plus an additional optional argument to provide labeling.

       [20]   Added a new command critcl::checklink which not only tries to check the environment
              via compiling the code, but also its linkability.

       [21]   Added  a  new  command critcl::msg for messaging, like command critcl::error is for
              error reporting. Likewise this is a hook a  user  of  the  package  is  allowed  to
              override.  The default implementation, used by mode compile & run does nothing. The
              implementation for mode generate package prints the message to stdout.

              Envisioned use is for the reporting of  results  determined  by  critcl::check  and
              critcl::checklink during building, to help with debugging when something goes wrong
              with a check.

       [22]   Exposed the argument processing internals  of  critcl::proc  for  use  by  advanced
              users. The new commands are

              [1]    critcl::argnames

              [2]    critcl::argcnames

              [3]    critcl::argcsignature

              [4]    critcl::argvardecls

              [5]    critcl::argconversion

              Please see section Advanced Embedded C Code of the critcl package documentation for
              details.

       [23]   Extended the critcl package to intercept package provide and  record  the  file  ->
              package  name  mapping. Plus other internal changes now allow the use of namespaced
              package names while still using proper path names and init function.

       [24]   Dropped the unused commands critcl::optimize and critcl::include.

       [25]   Dropped -lib mode from the critcl application.

       [26]   Dropped remnants of support for Tcl 8.3 and before.

AUTHORS

       Jean Claude Wippler, Steve Landers, Andreas Kupries

BUGS, IDEAS, FEEDBACK

       This document, and the package it describes,  will  undoubtedly  contain  bugs  and  other
       problems.   Please report them at https://github.com/andreas-kupries/critcl/issues.  Ideas
       for enhancements you may have for either package, application,  and/or  the  documentation
       are   also   very   welcome   and   should   be  reported  at  https://github.com/andreas-
       kupries/critcl/issues as well.

KEYWORDS

       C code, Embedded C Code, code generator, compile & run, compiler, dynamic code generation,
       dynamic   compilation,   generate  package,  linker,  on  demand  compilation,  on-the-fly
       compilation

CATEGORY

       Glueing/Embedded C code

COPYRIGHT

       Copyright (c) Jean-Claude Wippler
       Copyright (c) Steve Landers
       Copyright (c) 2011-2018 Andreas Kupries