#!/usr/bin/perl -w
    use Tk;
    use strict;    
    
    my $mw = MainWindow->new; 
    $mw->Label(-text => 'Number')->pack;
    my $nmbr = $mw->Entry(-width => 10);
    $nmbr->pack;  

    
    $mw->Button(
        -text => 'Print',
        -command => sub{do_print($nmbr);}
		)->pack;  
		  
	
	MainLoop;      
    
    
    sub do_print 
    {
        (my $nmbr) = @_;
        my $nmbr_val = $nmbr->get;
        print "Printing number $nmbr_val\n";
    }