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RedHat 9 (Linux i386) - man page for itclvars (redhat section n)

itclvars(n)				    [incr Tcl]				      itclvars(n)

       itclvars - variables used by [incr Tcl]

       The  following  global  variables  are created and managed automatically by the [incr Tcl]
       library.  Except where noted below, these variables should normally be  treated	as  read-
       only by application-specific code and by users.

	      When  an	interpreter  is created, [incr Tcl] initializes this variable to hold the
	      name of a directory containing the system library of [incr Tcl] scripts.	The  ini-
	      tial value of itcl::library is set from the ITCL_LIBRARY environment variable if it
	      exists, or from a compiled-in value otherwise.

	      When an interpreter is created, [incr Tcl] initializes this variable  to	hold  the
	      current  patch  level  for  [incr Tcl].	For  example, the value "2.0p1" indicates
	      [incr Tcl] version 2.0 with the first set of patches applied.

	      When an interpreter is created  containing  Tcl/Tk  and  the  [incr Tcl]	namespace
	      facility, this variable controls a "backward-compatibility" mode for widget access.

	      In  vanilla Tcl/Tk, there is a single pool of commands, so the access command for a
	      widget is the same as the window name.  When a widget is created	within	a  names-
	      pace,  however,  its  access  command is installed in that namespace, and should be
	      accessed outside of the namespace using a qualified name.  For  example,	namespace
	      foo {
		  namespace bar {
		      button .b -text "Testing"
		  }  }	foo::bar::.b  configure -background red pack .b Note that the window name
	      ".b" is still used in conjunction with commands like pack  and  destroy.	 However,
	      the access command for the widget (i.e., name that appears as the first argument on
	      a command line) must be more specific.

	      The "winfo command" command can be used to query the fully-qualified access command
	      for  any widget, so one can write: [winfo command .b] configure -background red and
	      this is good practice when writing library procedures.  Also, in	conjunction  with
	      the  bind  command,  the "%q" field can be used in place of "%W" as the access com-
	      mand: bind Button <Key-Return> {%q flash; %q  invoke}  While  this  behavior  makes
	      sense from the standpoint of encapsulation, it causes problems with existing Tcl/Tk
	      applications.  Many existing applications are written with bindings that use  "%W".
	      Many library procedures assume that the window name is the access command.

	      The itcl::purist variable controls a backward-compatibility mode.  By default, this
	      variable is "0", and the window name can be used as an access command in	any  con-
	      text.  Whenever the unknown procedure stumbles across a widget name, it simply uses
	      "winfo command" to determine the appropriate command name.  If this variable is set
	      to "1", this backward-compatibility mode is disabled.  This gives better encapsula-
	      tion, but using the window name as the access command may lead to "invalid command"

	      When  an	interpreter  is created, [incr Tcl] initializes this variable to hold the
	      version number of the form x.y.  Changes to x represent major changes with probable
	      incompatibilities  and changes to y represent small enhancements and bug fixes that
	      retain backward compatibility.

       itcl, variables

itcl					       3.0				      itclvars(n)

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