Provided by: tcl9.0-doc_9.0.2+dfsg-1_all 
NAME
info - Information about the state of the Tcl interpreter
SYNOPSIS
info option ?arg arg ...?
________________________________________________________________________________________________________________
DESCRIPTION
Available commands:
info args procname
Returns the names of the parameters to the procedure named procname.
info body procname
Returns the body of the procedure named procname.
info class subcommand class ?arg ...
Returns information about the class named class. See CLASS INTROSPECTION below.
info cmdcount
Returns the total number of commands evaluated in this interpreter.
info cmdtype commandName
Returns a the type of the command named commandName. Built-in types are: 2
alias 2
commandName was created by interp alias. In a safe interpreter an alias is only visible if 2
both the alias and the target are visible. 2
coroutine 2
commandName was created by coroutine. 2
ensemble 2
commandName was created by namespace ensemble. 2
import 2
commandName was created by namespace import. 2
native 2
commandName was created by the Tcl_CreateObjCommand interface directly without further 2
registration of the type of command. 2
object 2
commandName is the public command that represents an instance of oo::object or one of its 2
subclasses. 2
privateObject 2
commandName is the private command, my by default, that represents an instance of 2
oo::object or one of its subclasses. 2
proc 2
commandName was created by proc. 2
interp 2
commandName was created by interp create. 2
zlibStream 2
commandName was created by zlib stream. 2
info commands ?pattern?
Returns the names of all commands visible in the current namespace. If pattern is given, returns
only those names that match according to string match. Only the last component of pattern is a
pattern. Other components identify a namespace. See NAMESPACE RESOLUTION in the namespace(3tcl)
documentation.
info complete command
Returns 1 if command is a complete command, and 0 otherwise. Typically used in line-oriented
input environments to allow users to type in commands that span multiple lines.
info constant varName
Returns 1 if varName is a constant variable (see const) and 0 otherwise. 2
info consts ?pattern?
Returns the list of constant variables (see const) in the current scope, or the list of constant 2
variables matching pattern (if that is provided) in a manner similar to info vars.
info coroutine
Returns the name of the current coroutine, or the empty string if there is no current coroutine or
the current coroutine has been deleted.
info default procname parameter varname
If the parameter parameter for the procedure named procname has a default value, stores that value
in varname and returns 1. Otherwise, returns 0.
info errorstack ?interp?
Returns a description of the active command at each level for the last error in the current
interpreter, or in the interpreter named interp if given.
The description is a dictionary of tokens and parameters. Tokens are currently either CALL, UP, or
INNER, but other values may be introduced in the future. CALL indicates a command call, and its
parameter is the corresponding info level 0. UP indicates a shift in variable frames generated by
uplevel or similar, and applies to the previous CALL item. Its parameter is the level offset.
INNER identifies the “inner context”, which is the innermost atomic command or bytecode
instruction that raised the error, along with its arguments when available. While CALL and UP
provide a trail of the call path, INNER provides details of the offending operation in the
innermost procedure call, even to sub-expression granularity.
This information is also present in the -errorstack entry of the options dictionary returned by
3-argument catch; info errorstack is a convenient way of retrieving it for uncaught errors at top-
level in an interactive interpreter.
info exists varName
Returns 1 if a variable named varName is visible and has been defined, and 0 otherwise.
info frame ?depth?
Returns the depth of the call to info frame itself. Otherwise, returns a dictionary describing
the active command at the depth, which counts all commands visible to info level, plus commands
that don't create a new level, such as eval, source, or uplevel. The frame depth is always greater
than the current level.
If depth is greater than 0 it is the frame at that depth. Otherwise it is the number of frames up
from the current frame.
As with info level and error traces, for nested commands like “foo [bar [x]]”, only “x” is seen by
info frame invoked within “x”.
The dictionary may contain the following keys:
type Always present. Possible values are source, proc, eval, and precompiled.
source A script loaded via the source command.
proc The body of a procedure that could not be traced back to a line in a particular
script.
eval The body of a script provided to eval or uplevel.
precompiled
A precompiled script (loadable by the package tbcload), and no further information
is available.
line The line number of of the command inside its script. Not available for precompiled
commands. When the type is source, the line number is relative to the beginning of the
file, whereas for the last two types it is relative to the start of the script.
file For type source, provides the normalized path of the file that contains the command.
cmd The command before substitutions were performed.
proc For type proc, the name of the procedure containing the command.
lambda For a command in a script evaluated as the body of an unnamed routine via the apply
command, the definition of that routine.
level For a frame that corresponds to a level, (to be determined).
When a command can be traced to its literal definition in some script, e.g. procedures nested in
statically defined procedures, and literal eval scripts in files or statically defined procedures,
its type is source and its location is the absolute line number in the script. Otherwise, its
type is proc and its location is its line number within the body of the procedure.
In contrast, procedure definitions and eval within a dynamically evaluated environment count line
numbers relative to the start of their script, even if they would be able to count relative to the
start of the outer dynamic script. That type of number usually makes more sense.
A different way of describing this behaviour is that file-based locations are tracked as deeply as
possible, and where this is not possible the lines are counted based on the smallest possible eval
or procedure body, as that scope is usually easier to find than any dynamic outer scope.
The syntactic form {*} is handled like eval. I.e. if it is given a literal list argument the
system tracks the line number within the list words as well, and otherwise all line numbers are
counted relative to the start of each word (smallest scope)
info functions ?pattern?
If pattern is not given, returns a list of all the math functions currently defined. If pattern
is given, returns only those names that match pattern according to string match.
info globals ?pattern?
If pattern is not given, returns a list of all the names of currently-defined global variables.
Global variables are variables in the global namespace. If pattern is given, only those names
matching pattern are returned. Matching is determined using the same rules as for string match.
info hostname
Returns the name of the current host.
This name is not guaranteed to be the fully-qualified domain name of the host. Where machines
have several different names, as is common on systems with both TCP/IP (DNS) and NetBIOS-based
networking installed, it is the name that is suitable for TCP/IP networking that is returned.
info level ?level?
If number is not given, the level this routine was called from. Otherwise returns the complete
command active at the given level. If number is greater than 0, it is the desired level.
Otherwise, it is number levels up from the current level. A complete command is the words in the
command, with all substitutions performed, meaning that it is a list. See uplevel for more
information on levels.
info library
Returns the value of tcl_library, which is the name of the library directory in which the scripts
distributed with Tcl scripts are stored.
info loaded ?interp? ?prefix?
Returns the name of each file loaded in interp by the load command with prefix prefix . If prefix
is not given, returns a list where each item is the name of the loaded file and the prefix for
which the file was loaded. For a statically-loaded package the name of the file is the empty
string. For interp, the empty string is the current interpreter.
info locals ?pattern?
If pattern is given, returns the name of each local variable matching pattern according to string
match. Otherwise, returns the name of each local variable. A variables defined with the global,
upvar or variable is not local.
info nameofexecutable
Returns the absolute pathname of the program for the current interpreter. If such a file can not
be identified an empty string is returned.
info object subcommand object ?arg ...
Returns information about the object named object. subcommand is described OBJECT INTROSPECTION
below.
info patchlevel
Returns the value of the global variable tcl_patchLevel, in which the exact version of the Tcl
library initially stored.
info procs ?pattern?
Returns the names of all visible procedures. If pattern is given, returns only those names that
match according to string match. Only the final component in pattern is actually considered a
pattern. Any qualifying components simply select a namespace. See NAMESPACE RESOLUTION in the
namespace(3tcl) documentation.
info script ?filename?
Returns the pathname of the innermost script currently being evaluated, or the empty string if no
pathname can be determined. If filename is given, sets the return value of any future calls to
info script for the duration of the innermost active script. This is useful in virtual file
system applications.
info sharedlibextension
Returns the extension used on this platform for names of shared libraries, e.g. .so under
Solaris. Returns the empty string if shared libraries are not supported on this platform.
info tclversion
Returns the value of the global variable tcl_version, in which the major and minor version of the
Tcl library are stored.
info vars ?pattern?
If pattern is not given, returns the names of all visible variables. If pattern is given, returns
only those names that match according to string match. Only the last component of pattern is a
pattern. Other components identify a namespace. See NAMESPACE RESOLUTION in the namespace(3tcl)
documentation. When pattern is a qualified name, results are fully qualified.
A variable that has been declared but not yet given a value will be included in the results.
CLASS INTROSPECTION
The following subcommand values are supported by info class:
info class call class method
Returns a description of the method implementations that are used to provide a stereotypical
instance of class's implementation of method (stereotypical instances being objects instantiated
by a class without having any object-specific definitions added). This consists of a list of lists
of four elements, where each sublist consists of a word that describes the general type of method
implementation (being one of method for an ordinary method, filter for an applied filter, private 2
for a private method, and unknown for a method that is invoked as part of unknown method
handling), a word giving the name of the particular method invoked (which is always the same as
method for the method type, and “unknown” for the unknown type), a word giving the fully qualified
name of the class that defined the method, and a word describing the type of method implementation
(see info class methodtype).
Note that there is no inspection of whether the method implementations actually use next to
transfer control along the call chain, and the call chains that this command files do not actually 2
contain private methods.
info class constructor class
This subcommand returns a description of the definition of the constructor of class class. The
definition is described as a two element list; the first element is the list of arguments to the
constructor in a form suitable for passing to another call to proc or a method definition, and the
second element is the body of the constructor. If no constructor is present, this returns the
empty list.
info class definition class method
This subcommand returns a description of the definition of the method named method of class class.
The definition is described as a two element list; the first element is the list of arguments to
the method in a form suitable for passing to another call to proc or a method definition, and the
second element is the body of the method.
info class definitionnamespace class ?kind?
This subcommand returns the definition namespace for kind definitions of the class class; the 2
definition namespace only affects the instances of class, not class itself. The kind can be either 2
-class to return the definition namespace used for oo::define, or -instance to return the 2
definition namespace used for oo::objdefine; the -class kind is default (though this is only 2
actually useful on classes that are subclasses of oo::class). 2
If class does not provide a definition namespace of the given kind, this command returns the empty 2
string. In those circumstances, the oo::define and oo::objdefine commands look up which definition 2
namespace to use using the class inheritance hierarchy. 2
info class destructor class
This subcommand returns the body of the destructor of class class. If no destructor is present,
this returns the empty string.
info class filters class
This subcommand returns the list of filter methods set on the class.
info class forward class method
This subcommand returns the argument list for the method forwarding called method that is set on
the class called class.
info class instances class ?pattern?
This subcommand returns a list of instances of class class. If the optional pattern argument is
present, it constrains the list of returned instances to those that match it according to the
rules of string match.
info class methods class ?options...?
This subcommand returns a list of all public (i.e. exported) methods of the class called class.
Any of the following options may be given, controlling exactly which method names are returned:
-all If the -all flag is given, and the -scope flag is not given, the list of methods will 2
include those methods defined not just by the class, but also by the class's superclasses
and mixins.
-private
If the -private flag is given, and the -scope flag is not given, the list of methods will 2
also include the non-exported methods of the class (and superclasses and mixins, if -all is
also given). Note that this naming is an unfortunate clash with true private methods; this 2
option name is retained for backward compatibility.
-scope scope
Returns a list of all methods on class that have the given visibility scope. When this 2
option is supplied, both the -all and -private options are ignored. The valid values for 2
scope are: 2
public 2
Only methods with public scope (i.e., callable from anywhere by any instance of this 2
class) are to be returned. 2
unexported 2
Only methods with unexported scope (i.e., only callable via my) are to be returned. 2
private 2
Only methods with private scope (i.e., only callable from within this class's methods) 2
are to be returned. 2
info class methodtype class method
This subcommand returns a description of the type of implementation used for the method named
method of class class. When the result is method, further information can be discovered with info
class definition, and when the result is forward, further information can be discovered with info
class forward.
info class mixins class
This subcommand returns a list of all classes that have been mixed into the class named class.
info class properties class ?options...
This subcommand returns a sorted list of properties defined on the class named class. The options 2
define exactly which properties are returned: 2
-all 2
With this option, the properties from the superclasses and mixins of the class are also 2
returned. 2
-readable 2
This option (the default behavior) asks for the readable properties to be returned. Only 2
readable or writable properties are returned, not both. 2
-writable 2
This option asks for the writable properties to be returned. Only readable or writable 2
properties are returned, not both. 2
info class subclasses class ?pattern?
This subcommand returns a list of direct subclasses of class class. If the optional pattern
argument is present, it constrains the list of returned classes to those that match it according
to the rules of string match.
info class superclasses class
This subcommand returns a list of direct superclasses of class class in inheritance precedence
order.
info class variables class ?-private?
This subcommand returns a list of all variables that have been declared for the class named class
(i.e. that are automatically present in the class's methods, constructor and destructor). If the 2
-private option is given, this lists the private variables declared instead.
OBJECT INTROSPECTION
The following subcommand values are supported by info object:
info object call object method
Returns a description of the method implementations that are used to provide object's
implementation of method. This consists of a list of lists of four elements, where each sublist
consists of a word that describes the general type of method implementation (being one of method
for an ordinary method, filter for an applied filter, private for a private method, and unknown 2
for a method that is invoked as part of unknown method handling), a word giving the name of the
particular method invoked (which is always the same as method for the method type, and “unknown”
for the unknown type), a word giving what defined the method (the fully qualified name of the
class, or the literal string object if the method implementation is on an instance), and a word
describing the type of method implementation (see info object methodtype).
Note that there is no inspection of whether the method implementations actually use next to
transfer control along the call chain, and the call chains that this command files do not actually 2
contain private methods.
info object class object ?className?
If className is not given, this subcommand returns class of the object object. If className is
present, this subcommand returns a boolean value indicating whether the object is of that class.
info object creationid object
Returns the unique creation identifier for the object object. This creation identifier is unique 2
to the object (within a Tcl interpreter) and cannot be controlled at object creation time or 2
altered afterwards. 2
Implementation note: the creation identifier is used to generate unique identifiers associated 2
with the object, especially for private variables. 2
info object definition object method
This subcommand returns a description of the definition of the method named method of object
object. The definition is described as a two element list; the first element is the list of
arguments to the method in a form suitable for passing to another call to proc or a method
definition, and the second element is the body of the method.
info object filters object
This subcommand returns the list of filter methods set on the object.
info object forward object method
This subcommand returns the argument list for the method forwarding called method that is set on
the object called object.
info object isa category object ?arg?
This subcommand tests whether an object belongs to a particular category, returning a boolean
value that indicates whether the object argument meets the criteria for the category. The
supported categories are:
info object isa class object
This returns whether object is a class (i.e. an instance of oo::class or one of its
subclasses).
info object isa metaclass object
This returns whether object is a class that can manufacture classes (i.e. is oo::class or a
subclass of it).
info object isa mixin object class
This returns whether class is directly mixed into object.
info object isa object object
This returns whether object really is an object.
info object isa typeof object class
This returns whether class is the type of object (i.e. whether object is an instance of
class or one of its subclasses, whether direct or indirect).
info object methods object ?option...?
This subcommand returns a list of all public (i.e. exported) methods of the object called object.
Any of the following options may be given, controlling exactly which method names are returned:
-all If the -all flag is given, and the -scope flag is not given, the list of methods will 2
include those methods defined not just by the object, but also by the object's class and
mixins, plus the superclasses of those classes.
-private
If the -private flag is given, and the -scope flag is not given, the list of methods will 2
also include the non-exported methods of the object (and classes, if -all is also given). 2
Note that this naming is an unfortunate clash with true private methods; this option name 2
is retained for backward compatibility.
-scope scope
Returns a list of all methods on object that have the given visibility scope. When this 2
option is supplied, both the -all and -private options are ignored. The valid values for 2
scope are: 2
public 2
Only methods with public scope (i.e., callable from anywhere) are to be returned. 2
unexported 2
Only methods with unexported scope (i.e., only callable via my) are to be returned. 2
private 2
Only methods with private scope (i.e., only callable from within this object's instance 2
methods) are to be returned. 2
info object methodtype object method
This subcommand returns a description of the type of implementation used for the method named
method of object object. When the result is method, further information can be discovered with
info object definition, and when the result is forward, further information can be discovered with
info object forward.
info object mixins object
This subcommand returns a list of all classes that have been mixed into the object named object.
info object namespace object
This subcommand returns the name of the internal namespace of the object named object.
info object properties object ?options...
This subcommand returns a sorted list of properties defined on the object named object. The 2
options define exactly which properties are returned: 2
-all 2
With this option, the properties from the class, superclasses and mixins of the object are 2
also returned. 2
-readable 2
This option (the default behavior) asks for the readable properties to be returned. Only 2
readable or writable properties are returned, not both. 2
-writable 2
This option asks for the writable properties to be returned. Only readable or writable 2
properties are returned, not both. 2
info object variables object ?-private?
This subcommand returns a list of all variables that have been declared for the object named
object (i.e. that are automatically present in the object's methods). If the -private option is 2
given, this lists the private variables declared instead.
info object vars object ?pattern?
This subcommand returns a list of all variables in the private namespace of the object named
object. If the optional pattern argument is given, it is a filter (in the syntax of a string match
glob pattern) that constrains the list of variables returned. Note that this is different from the
list returned by info object variables; that can include variables that are currently unset,
whereas this can include variables that are not automatically included by any of object's methods
(or those of its class, superclasses or mixins).
EXAMPLES
This command prints out a procedure suitable for saving in a Tcl script:
proc printProc {procName} {
set result [list proc $procName]
set formals {}
foreach var [info args $procName] {
if {[info default $procName $var def]} {
lappend formals [list $var $def]
} else {
# Still need the list-quoting because variable
# names may properly contain spaces.
lappend formals [list $var]
}
}
puts [lappend result $formals [info body $procName]]
}
EXAMPLES WITH OBJECTS
Every object necessarily knows what its class is; this information is trivially extractable through
introspection:
oo::class create c
c create o
puts [info object class o]
→ prints "::c"
puts [info object class c]
→ prints "::oo::class"
The introspection capabilities can be used to discover what class implements a method and get how it is
defined. This procedure illustrates how:
proc getDef {obj method} {
foreach inf [info object call $obj $method] {
lassign $inf calltype name locus methodtype
# Assume no forwards or filters, and hence no $calltype
# or $methodtype checks...
if {$locus eq "object"} {
return [info object definition $obj $name]
} else {
return [info class definition $locus $name]
}
}
error "no definition for $method"
}
This is an alternate way of looking up the definition; it is implemented by manually scanning the list of
methods up the inheritance tree. This code assumes that only single inheritance is in use, and that there
is no complex use of mixed-in classes (in such cases, using info object call as above is the simplest way
of doing this by far):
proc getDef {obj method} {
if {$method in [info object methods $obj]} {
# Assume no forwards
return [info object definition $obj $method]
}
set cls [info object class $obj]
while {$method ni [info class methods $cls]} {
# Assume the simple case
set cls [lindex [info class superclass $cls] 0]
if {$cls eq ""} {
error "no definition for $method"
}
}
# Assume no forwards
return [info class definition $cls $method]
}
SEE ALSO
global(3tcl), oo::class(3tcl), oo::define(3tcl), oo::object(3tcl), proc(3tcl), self(3tcl),
tcl_library(3tcl), tcl_patchLevel(3tcl), tcl_version(3tcl)
KEYWORDS
command, information, interpreter, introspection, level, namespace, object, procedure, variable
Tcl 8.4 info(3tcl)