use strict;
use warnings;
use Tk;

my $mw = new MainWindow(-title => "Pk");
my $qst = $mw -> Label(-text => "Entry validation") -> pack();

# punctuation not allowed
my $rsp = $mw -> Entry(-validate => "key",
                       -validatecommand => sub {$_[1] !~ /[;,.:!?]/}, 
                       -invalidcommand  => sub {$mw->bell}) ->pack();
my $button = $mw ->Button(-text => "Quit", 
        	           -command => sub { exit }) -> pack();
MainLoop;

__END__