#!/usr/bin/perl -w 
                                                                         
use Tk;
use strict; 
                                                                    
my $mw = MainWindow->new;     

	my $var=0;

	my $button_A = $mw->Button( 
    -text    => '  Button A', 
    -command =>[\&rutine, $var, ]);#
    $button_A->pack; 
    
    my $button_B = $mw->Button( 
    -text    => ' ++ ', 
    -command => sub{$var++;  print"\$var is $var!\n";});
    $button_B->pack; 
    
    my $button_C = $mw->Button( 
    -text    => ' -- ', 
    -command => sub{$var--; print"\$var is $var!\n";});
    $button_C->pack; 
	
MainLoop;


sub rutine
{
	my ($var)=@_;
	
	print "$var\n";

}