Yurttas/PL/SL/perl/F/11/00/01/p 01.pl

 1#!/usr/bin/perl
 2
 3use Tk;
 4
 5my $window = MainWindow->new;
 6$window->title("A first Tk Demo");
 7$window->Label(-text => "This is a chunk of descriptive text")->pack;
 8$window->Button(-text => "Print a value", -command => \&but )->pack;
 9$window->Button(-text => "Double the value", -command => sub {$val*=2} )->pack;
10$window->Button(-text => "This is a quit button ", -command => \&finito )->pack;
11MainLoop;
12
13###############################################
14
15sub but {
16print "value is $val\n";
17}
18
19sub finito{
20print "going away ...\n";
21print "final value is $val\n";
22exit;
23}
24
25sub BEGIN {
26$val = 2;
27}