#!/usr/bin/perl -w
#
use strict;
use Tk;

my $mw = tkinit();
my @text = qw(Checkbox1 Checkbox2 Checkbox3 Checkbox4);
my @var;

for my$i (0..$#text) {
   $mw->Checkbutton(-text => $text[$i],
                    -variable => \$var[$i],
                    -command => [\&select,$i])->pack;
}

MainLoop;

#
#----------------------------------------------------------
#

sub select {
   my $i = shift;

   for my$j (0..$#text) {
     if ($var[$j] == 1) { $var[$j] = 0 }
     if ($j == $i)      { $var[$j] = 1 }
   }
}