oracular (3) critcl_pkg.3tcl.gz

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