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info(n)			     Tcl Built-In Commands		       info(n)

______________________________________________________________________________

NAME
       info - Return information about the state of the	Tcl interpreter

SYNOPSIS
       info option ?arg	arg ...?
______________________________________________________________________________

DESCRIPTION
       This  command  provides	information about various internals of the Tcl
       interpreter.  The legal options (which may be abbreviated) are:

       info args procname
	      Returns a	list containing	the names of the arguments  to	proce-
	      dure  procname,  in  order.   Procname must be the name of a Tcl
	      command procedure.

       info body procname
	      Returns the body of procedure procname.  Procname	 must  be  the
	      name of a	Tcl command procedure.

       info class subcommand class ?arg	...
	      Returns  information about the class, class. The subcommands are |
	      described	in CLASS INTROSPECTION below.

       info cmdcount
	      Returns a	count of the total number of commands that  have  been
	      invoked in this interpreter.

       info commands ?pattern?
	      If  pattern is not specified, returns a list of names of all the
	      Tcl commands visible (i.e. executable without using a  qualified
	      name) to the current namespace, including	both the built-in com-
	      mands written in C and the command procedures defined using  the
	      proc  command.  If pattern is specified, only those names	match-
	      ing pattern are returned.	 Matching is determined	using the same
	      rules as for string match.  pattern can be a qualified name like
	      Foo::print*.  That is, it	may specify a particular namespace us-
	      ing  a  sequence	of  namespace names separated by double	colons
	      (::), and	may have pattern matching special  characters  at  the
	      end  to specify a	set of commands	in that	namespace.  If pattern
	      is a qualified name, the resulting list  of  command  names  has
	      each one qualified with the name of the specified	namespace, and
	      only the commands	defined	in the named namespace are returned.

       info complete command
	      Returns 1	if command is a	complete Tcl command in	the  sense  of
	      having  no  unclosed  quotes,  braces, brackets or array element
	      names.  If the command does not appear to	be complete then 0  is
	      returned.	 This command is typically used	in line-oriented input
	      environments to allow users to type in commands that span	multi-
	      ple lines;  if the command is not	complete, the script can delay
	      evaluating it until additional lines have	been typed to complete
	      the command.

       info coroutine
	      Returns  the  name  of the currently executing coroutine,	or the |
	      empty string if either no	coroutine is currently	executing,  or |
	      the current coroutine has	been deleted (but has not yet returned |
	      or yielded since deletion).

       info default procname arg varname
	      Procname must be the name	of a Tcl  command  procedure  and  arg
	      must  be the name	of an argument to that procedure.  If arg does
	      not have a default value then the	command	returns	0.   Otherwise
	      it  returns  1 and places	the default value of arg into variable
	      varname.

       info errorstack ?interp?
	      Returns, in a form that is programmatically easy to  parse,  the |
	      function	names  and arguments at	each level from	the call stack |
	      of the last error	in the given interp, or	in the current one  if |
	      not specified.						       |

	      This  form  is an	even-sized list	alternating tokens and parame- |
	      ters. Tokens are currently either	CALL, UP, or INNER, but	 other |
	      values  may be introduced	in the future. CALL indicates a	proce- |
	      dure 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 allow to follow complex call paths, INNER homes in	on the |
	      offending	 operation in the innermost procedure call, even going |
	      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 tclsh.				       |

       info exists varName
	      Returns  1  if  the variable named varName exists	in the current
	      context (either as a global or local variable) and has been  de-
	      fined by being given a value, returns 0 otherwise.

       info frame ?number?
	      This  command  provides  access to all frames on the stack, even
	      those hidden from	info level. If number is not  specified,  this
	      command  returns a number	giving the frame level of the command.
	      This is 1	if the command is invoked at top-level.	If  number  is
	      specified,  then the result is a dictionary containing the loca-
	      tion information for the command at the numbered	level  on  the
	      stack.

	      If  number  is positive (> 0) then it selects a particular stack
	      level (1 refers to the outer-most	active command,	2 to the  com-
	      mand  it	called,	and so on, up to the current frame level which
	      refers to	info frame itself); otherwise it gives a  level	 rela-
	      tive  to	the  current command (0	refers to the current command,
	      i.e., info frame itself, -1 to its caller, and so	on).

	      This is similar to how info level	works, except that  this  sub-
	      command  reports	all  frames,  like sourced scripts, evals, up-
	      levels, etc.

	      Note that	for nested commands, like "foo [bar  [x]]",  only  "x"
	      will  be	seen by	an info	frame invoked within "x".  This	is the
	      same as for info level and error stack traces.

	      The result dictionary may	contain	the keys  listed  below,  with
	      the specified meanings for their values:

	      type   This  entry is always present and describes the nature of
		     the location for the command. The recognized  values  are
		     source, proc, eval, and precompiled.

		     source
			    means that the command is found in a script	loaded
			    by the source command.

		     proc
			    means that the command  is	found  in  dynamically
			    created procedure body.

		     eval
			    means  that	the command is executed	by eval	or up-
			    level.

		     precompiled
			    means that the command is found in a  pre-compiled
			    script  (loadable  by the package tbcload),	and no
			    further information	will be	available.

	      line   This entry	provides the number of the line	the command is
		     at	inside of the script it	is a part of. This information
		     is	not present for	type precompiled. For type source this
		     information  is  counted relative to the beginning	of the
		     file, whereas for the last	two types the line is  counted
		     relative to the start of the script.

	      file   This  entry  is present only for type source. It provides
		     the normalized path of the	file the command is in.

	      cmd    This entry	provides the string representation of the com-
		     mand. This	is usually the unsubstituted form, however for
		     commands which are	a canonically-constructed list	(e.g.,
		     as	 produced  by the list command)	executed by eval it is
		     the substituted form as they have no other	string	repre-
		     sentation.	 Care  is taken	that the canonicality property
		     of	the latter is not spoiled.

	      proc   This entry	is present only	if the command is found	in the
		     body  of  a  regular  Tcl procedure. It then provides the
		     name of that procedure.

	      lambda This entry	is present only	if the command is found	in the
		     body  of  an  anonymous  Tcl procedure, i.e. a lambda. It
		     then provides the entire  definition  of  the  lambda  in
		     question.

	      level  This  entry  is  present  only if the queried frame has a
		     corresponding frame returned by info level.  It  provides
		     the index of this frame, relative to the current level (0
		     and negative numbers).

	      A	thing of note is that for  procedures  statically  defined  in
	      files the	locations of commands in their bodies will be reported
	      with type	source and absolute line  numbers,  and	 not  as  type
	      proc.  The  same is true for procedures nested in	statically de-
	      fined procedures,	and literal eval scripts in  files  or	stati-
	      cally defined procedures.

	      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  usu-
	      ally 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	possi-
	      ble 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	specified, returns a  list  of	all  the  math
	      functions	 currently  defined.   If  pattern  is specified, only
	      those functions whose name matches pattern are returned.	Match-
	      ing is determined	using the same rules as	for string match.

       info globals ?pattern?
	      If  pattern is not specified, returns a list of all the names of
	      currently-defined	global variables.  Global variables are	 vari-
	      ables  in	 the  global namespace.	 If pattern is specified, only
	      those names matching pattern are returned.  Matching  is	deter-
	      mined using the same rules as for	string match.

       info hostname
	      Returns the name of the computer on which	this invocation	is be-
	      ing executed.  Note that 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 ?number?
	      If number	is not specified, this command returns a number	giving
	      the  stack  level	of the invoking	procedure, or 0	if the command
	      is invoked at top-level.	If number is specified,	then  the  re-
	      sult is a	list consisting	of the name and	arguments for the pro-
	      cedure call at level number on the stack.	 If number is positive
	      then  it	selects	a particular stack level (1 refers to the top-
	      most active procedure, 2 to the procedure	it called, and so on);
	      otherwise	 it  gives  a  level  relative to the current level (0
	      refers to	the current procedure, -1 to its caller, and  so  on).
	      See  the uplevel command for more	information on what stack lev-
	      els mean.

       info library
	      Returns the name of the library directory	in which standard  Tcl
	      scripts  are  stored.  This is actually the value	of the tcl_li-
	      brary variable and may be	changed	by setting tcl_library.

       info loaded ?interp?
	      Returns a	list describing	all of the  packages  that  have  been
	      loaded  into interp with the load	command.  Each list element is
	      a	sub-list with two elements consisting of the name of the  file
	      from  which  the package was loaded and the name of the package.
	      For statically-loaded packages the file name will	 be  an	 empty
	      string.	If  interp is omitted then information is returned for
	      all packages loaded in any interpreter in	the process.  To get a
	      list of just the packages	in the current interpreter, specify an
	      empty string for the interp argument.

       info locals ?pattern?
	      If pattern is not	specified, returns a list of all the names  of
	      currently-defined	 local	variables,  including arguments	to the
	      current procedure, if any.  Variables defined with  the  global,
	      upvar   and  variable commands will not be returned.  If pattern
	      is specified, only those names matching  pattern	are  returned.
	      Matching is determined using the same rules as for string	match.

       info nameofexecutable
	      Returns the full path name of the	binary file from which the ap-
	      plication	was invoked.  If Tcl was unable	to identify the	 file,
	      then an empty string is returned.

       info object subcommand object ?arg ...
	      Returns  information  about  the object, object. The subcommands |
	      are described in OBJECT INTROSPECTION below.

       info patchlevel
	      Returns the value	of the global variable	tcl_patchLevel,	 which
	      holds the	exact version of the Tcl library by default.

       info procs ?pattern?
	      If  pattern is not specified, returns a list of all the names of
	      Tcl command procedures in	the current namespace.	If pattern  is
	      specified,  only	those procedure	names in the current namespace
	      matching pattern are returned.  Matching is determined using the
	      same  rules  as for string match.	 If pattern contains any name-
	      space separators,	they are used to select	a  namespace  relative
	      to the current namespace (or relative to the global namespace if
	      pattern starts with ::) to match within; the matching pattern is
	      taken to be the part after the last namespace separator.

       info script ?filename?
	      If a Tcl script file is currently	being evaluated	(i.e. there is
	      a	call to	Tcl_EvalFile active or there is	an  active  invocation
	      of  the  source  command), then this command returns the name of
	      the innermost file being processed.  If filename	is  specified,
	      then  the	 return	value of this command will be modified for the
	      duration of the active invocation	to return that name.  This  is
	      useful  in virtual file system applications.  Otherwise the com-
	      mand returns an empty string.

       info sharedlibextension
	      Returns the extension used on this platform  for	the  names  of
	      files  containing	 shared	 libraries (for	example, .so under So-
	      laris).  If shared libraries are not supported on	this  platform
	      then an empty string is returned.

       info tclversion
	      Returns  the  value  of  the  global variable tcl_version, which
	      holds the	major and minor	version	of the Tcl library by default.

       info vars ?pattern?
	      If pattern is not	specified, returns a list of all the names  of
	      currently-visible	 variables.   This  includes  locals  and cur-
	      rently-visible globals.  If pattern  is  specified,  only	 those
	      names matching pattern are returned.  Matching is	determined us-
	      ing the same rules as for	string match.  pattern can be a	quali-
	      fied name	like Foo::option*.  That is, it	may specify a particu-
	      lar namespace using a sequence of	namespace names	 separated  by
	      double  colons (::), and may have	pattern	matching special char-
	      acters at	the end	to specify a set of variables  in  that	 name-
	      space.   If  pattern  is a qualified name, the resulting list of
	      variable names has each matching	namespace  variable  qualified
	      with  the	 name of its namespace.	 Note that a currently-visible
	      variable may not yet "exist" if it has  not  been	 set  (e.g.  a
	      variable declared	but not	set by variable).

   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  implementa- |
	      tion  of method (stereotypical instances being objects instanti- |
	      ated 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, and	unknown	for  a	method |
	      that is invoked as part of unknown method	handling), a word giv- |
	      ing 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 implemen- |
	      tations  actually	 use  next  to transfer	control	along the call |
	      chain.							       |

       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	 argu- |
	      ments  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 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  for- |
	      warding 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 specified,	controlling exactly which method names are re- |
	      turned:							       |

	      -all   If	 the  -all flag	is given, the list of methods will in- |
		     clude those methods defined not just by  the  class,  but |
		     also by the class's superclasses and mixins.

	      -private
		     If	 the  -private flag is given, the list of methods will |
		     also include the private (i.e. non-exported)  methods  of |
		     the  class	 (and superclasses and mixins, if -all is also |
		     given).						       |

       info class methodtype class method
	      This subcommand returns a	description of the type	of implementa- |
	      tion  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 subclasses class ?pattern?
	      This  subcommand	returns	 a  list of direct subclasses of class |
	      class. If	the optional pattern  argument	is  present,  it  con- |
	      strains  the list	of returned classes to those that match	it ac- |
	      cording 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
	      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).     |

   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  con- |
	      sists  of	 a  list of lists of four elements, where each sublist |
	      consists of a word that describes	the general type of method im- |
	      plementation (being one of method	for an ordinary	method,	filter |
	      for an applied filter, 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 what defined the method (the fully qualified  name |
	      of  the class, or	the literal string object if the method	imple- |
	      mentation	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 implemen- |
	      tations actually use next	to transfer  control  along  the  call |
	      chain.							       |

       info object class object	?className?
	      If  className  is	 unspecified, this subcommand returns class of |
	      the object object. If className is present, this subcommand  re- |
	      turns  a	boolean	value indicating whether the object is of that |
	      class.

       info object definition object method
	      This subcommand returns a	description of the definition  of  the |
	      method  named  method  of	 object	 object. The definition	is de- |
	      scribed as a two element list; the first element is the list  of |
	      arguments	 to  the  method in a form suitable for	passing	to an- |
	      other call to proc or a method definition, and the  second  ele- |
	      ment 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  for- |
	      warding 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 sup- |
	      ported 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 manufac- |
		     ture 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 sub- |
		     classes, 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 op- |
	      tions may	be specified, controlling exactly which	 method	 names |
	      are returned:						       |

	      -all   If	 the  -all flag	is given, the list of methods will in- |
		     clude those methods defined not just by the  object,  but |
		     also  by  the  object's class and mixins, plus the	super- |
		     classes of	those classes.

	      -private
		     If	the -private flag is given, the	list of	 methods  will |
		     also  include  the	private	(i.e. non-exported) methods of |
		     the object	(and classes, if -all is also given).	       |

       info object methodtype object method
	      This subcommand returns a	description of the type	of implementa- |
	      tion 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 variables object
	      This subcommand returns a	list of	all variables that  have  been |
	      declared	for  the  object named object (i.e. that are automati- |
	      cally present in the object's methods).

       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 re- |
	      turned. Note that	this is	different from the  list  returned  by |
	      info  object variables; that can include variables that are cur- |
	      rently 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  im- |
       plements	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	imple- |
       mented  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(n),   oo::class(n),   oo::define(n),   oo::object(n),   proc(n), |
       self(n),	tcl_library(n),	tcl_patchLevel(n), tcl_version(n)

KEYWORDS
       command,	information, interpreter, introspection, level,	namespace, ob- |
       ject, procedure,	variable

Tcl				      8.4			       info(n)

NAME | SYNOPSIS | DESCRIPTION | EXAMPLES | SEE ALSO | KEYWORDS

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