#!/usr/bin/perl
use strict;
use Tk;
use Data::Dumper;

my $mw = MainWindow->new;

for(0..4){
$mw->Button(-text => "Hello World$_",
                     -command=>[\&change])->pack;
}
MainLoop;

sub change {
#Tk dosn't pass it's widget reference in callbacks
#Only the bind() method will implicity pass a widget reference, and even
#this default (and generally preferred) action can be defeated.
#use $Tk::widget
print "sub-input->@_\n";
my $caller = $Tk::widget;
#print Dumper([$caller]);
print "$caller   ";
print $caller->{'_TkValue_'},'     ';
my $text = $caller->cget('-text');
print "$text\n";
$caller->configure(-text=>"Hello Stranger");
}