DESCRIPTION
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.
- itcl::library
- 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 initial value of itcl::library is set from the ITCL_LIBRARY environment variable if it exists, or from a compiled-in value otherwise.
- itcl::patchLevel
- 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.
- itcl::purist
-
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 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
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
-
bind Button <Key-Return> {%q flash; %q invoke}
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 context. 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 encapsulation, but using the window name as the access command may lead to "invalid command" errors.
-
- itcl::version
-
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.
KEYWORDS
itcl, variables