#!/usr/bin/perl
use warnings;
use Tk;

my $mw = tkinit;
my @buttons;

for $i ( 0..5 ) {
    $buttons[$i] = $mw->Button(-text => "Button $i",)->pack();
    $buttons[$i]->configure (-command => [\&printme, $buttons[$i]],);
}

my $reconbut = $mw->Button(-text => 'Reconfigure', -command => \&recon,)->pack();

MainLoop;

sub printme {
   print $_[0]->cget (-text) . "\n";
}

sub recon{
    $buttons[$_]->configure(-text => 'Button '. ($_ + 10)) for 0..$#buttons;
}