Chapter 23. Plethora of pTk Potpourri

23.1.1. 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.

23.1.2. Symbols Exported by Default

The use Tk statement exports these subroutines by default:

DoOneEvent

Handles Tk events. See Chapter 15, "Anatomy of the MainLoop".

Ev

Used in callback definitions to delay argument evaluation. See Chapter 15, "Anatomy of the MainLoop".

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).

23.1.3. 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)}.

*event

A localized version of a callback's event structure. See Chapter 15, "Anatomy of the MainLoop".

lsearch

Searches a list for an exact string match. It returns the ordinal of the match, or -1 if no match. For example: my $ord = lsearch(\@Selection,$i). The first argument is an array reference and the second the match string.

NoOp

A No Operation subroutine, commonly used to disable a callback.

$XS_VERSION

The XS version.

*widget

A localized version of the widget that owns the callback. See Chapter 15, "Anatomy of the MainLoop".

DONT_WAIT, WINDOW_EVENTS, FILE_EVENTS, TIMER_EVENTS, IDLE_EVENTS, ALL_EVENTS

DoOneEvent bit patterns. See Chapter 15, "Anatomy of the MainLoop".

NORMAL_BG, ACTIVE_BG, SELECT_BG, SELECT_FG, TROUGH, INDICATOR, DISABLED, BLACK, WHITE

Common colors.

23.1.4. Exporter Tags

You can import several symbols at once using an Exporter tag (for example, to get all the DoOneEvent bit patterns, do use Tk ':eventtypes'):

• :eventtypes => qw/DONT_WAIT WINDOW_EVENTS FILE_EVENTS TIMER_EVENTS IDLE_EVENTS ALL_EVENTS/

• :variables => qw/*widget *event/

• :colors => qw/NORMAL_BG ACTIVE_BG SELECT_BG SELECT_FG TROUGH INDICATOR DISABLED BLACK WHITE/