pTk Special Variables and Exporter Symbols
Before we get to the interesting stuff, we need to list the special variables and symbols unique to Perl/Tk.
Global Variables
These global variables are available for your use:
-
$Tk::VERSION
The Perl/Tk version, which incorporates the Tcl/Tk version it’s based upon, plus the Perl/Tk subrelease number.
'800.023'
is the 23rd Perl/Tk release based on Tcl/Tk 8.0.'803.xxx'
will be based on Tcl/Tk 8.3.-
$Tk::library
The pathname where the Tk modules are installed; for example:
/usr/local/lib/perl5/site_perl/5.6.0/i686-linux/Tk
.-
$Tk::platform
The platform, which is
'MSWin32'
for Win32 machines, otherwise'unix'
.-
$Tk::version
The base Tcl/Tk version, for example
'8.0'
.-
$Tk::patchLevel
The Tcl/Tk patch level, for example
'8.0'
.-
$Tk::strictMotif
A flag to force Tk to use pure Motif style windows.
Symbols Exported by Default
The use Tk
statement exports these subroutines by
default:
-
DoOneEvent
Handles Tk events. See Chapter 15.
-
Ev
Used in callback definitions to delay argument evaluation. See Chapter 15.
-
exit
Overrides Perl’s
CORE::exit
to clean up Tk data structures.-
Exists($widget)
Ensures that
$widget
is a valid Perl/Tk widget reference.-
MainLoop
Starts the Tk event loop.
-
tkinit(@args)
Shorthand for
MainWindow->new(@args)
.
Optionally Exported Symbols
You can import these symbols if desired:
-
catch
Executes a block of code, trapping and ignoring any errors. The code should be enclosed in a Perl block:
catch {$widget->cget(-state)} ...
Get Mastering Perl/Tk now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.