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

NAME
       itclvars - variables used by [incr Tcl]


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

       iittccll::::lliibbrraarryy
              When an interpreter  is  created,  [[iinnccrr TTccll]]  initializes  this
              variable  to  hold the name of a directory containing the system
              library  of  [[iinnccrr TTccll]]   scripts.    The   initial   value   of
              iittccll::::lliibbrraarryy  is set from the ITCLLIBRARY environment variable
              if it exists, or from a compiled-in value otherwise.

       iittccll::::ppaattcchhLLeevveell
              When an interpreter  is  created,  [[iinnccrr TTccll]]  initializes  this
              variable  to  hold  the current patch level for [[iinnccrr TTccll]].  For
              example, the value "22..00pp11" indicates [[iinnccrr TTccll]] version 2.0 with
              the first set of patches applied.

       iittccll::::ppuurriisstt
              When  an  interpreter  is  created  containing  Tcl/Tk  and  the
              [[iinnccrr TTccll]] namespace facility, this variable controls  a  "back-
              ward-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 namespace, 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 ppaacckk and ddeessttrrooyy.  However, the access command for the wid-
              get  (i.e., name that appears as the first argument on a command
              line) must be more specific.

              The "wwiinnffoo ccoommmmaanndd" command can be used to query the fully-qual-
              ified  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
              bbiinndd command, the "%q" field can be used in place of "%W" as the
              access  command:  bind Button  {%q flash; %q invoke}
              While this behavior makes sense from the standpoint of  encapsu-
              lation,  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  iittccll::::ppuurriisstt  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  context.   Whenever  the
              uunnkknnoowwnn  procedure stumbles across a widget name, it simply uses
              "wwiinnffoo ccoommmmaanndd" to determine the appropriate command  name.   If
              this variable is set to "1", this backward-compatibility mode is
              disabled.  This gives better encapsulation, but using the window
              name as the access command may lead to "invalid command" errors.

       iittccll::::vveerrssiioonn
              When an interpreter  is  created,  [[iinnccrr TTccll]]  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.


KKEEYYWWOORRDDSS
       itcl, variables



itcl                                  3.0                          itclvars(n)