Perl/Tk Pocket Reference

2 Perl/Tk Pocket Reference

where widgetClass is the name of the class of widget desired

(e.g., Button) and

$parent is the Perl/Tk widget reference of

the new widget’s parent. The Perl object reference is stored

in $widget, which becomes a child of $parent, creating the

widget hierarchy.

All widget creation commands can have the optional

Name => resourceName parameter to associate a resource

database name with the widget.

Every Perl/Tk program requires a main window, the topmost

widget in the hierarchy, created with:

$mw = MainWindow->new;

The following command creates a new button widget

$b and

uses the grid geometry manager to map it:

$b = $mw->Button(-text => “Hello World”)->grid;

Widget configuration options may be passed in the creation

method. Options begin with a “-” and are usually followed

by a value: an integer or string, sometimes a Perl scalar, array,

hash, or code reference. After creation, options may be

changed using the configure widget command:

$widget->configure(-option => value, ...);

and queried using the cget command:

$widget->cget(-option);

The last statement in a Perl/Tk program calls MainLoop to

initiate event processing.

Perl/Tk Callbacks

A callback is a scalar, either a code reference or a method

name as a string. Either of these styles can take parameters

by passing an array reference with the code reference or

method name as the first element, and subroutine parameters

as subsequent elements. ...