use strict;
use warnings;
use Tk;
use Tk::Radiobutton;
my $mw = Tk::MainWindow->new;

my $rb_value; # undef, no Radiobutton selected
$mw->Radiobutton(-text=>'first',-value=>'one',-variable=>\$rb_value)->pack(-anchor=>'w');
$mw->Radiobutton(-text=>'second',-value=>'one',-variable=>\$rb_value)->pack(-anchor=>'w');
$mw->Radiobutton(-text=>'third',-value=>'three',-variable=>\$rb_value)->pack(-anchor=>'w');

$mw->Label(-text=>'------------------------')->pack;

my $other_value = '0000ff'; # preset blue
$mw->Radiobutton(-text=>'RED',-value=>'ff0000',-variable=>\$other_value)->pack(-anchor=>'w');
$mw->Radiobutton(-text=>'GREEN',-value=>'00ff00',-variable=>\$other_value)->pack(-anchor=>'w');
$mw->Radiobutton(-text=>'BLUE',-value=>'0000ff',-variable=>\$other_value)->pack(-anchor=>'w');

MainLoop;
print 'rb:',$rb_value,$/;
print 'other:',$other_value,$/;