#!/usr/bin/perl
# Copyright 2004-2017, Paul Johnson (paul@pjcj.net)
# This software is free. It is licensed under the same terms as Perl itself.
# The latest version of this software should be available from my homepage:
# http://www.pjcj.net
package Foo;
sub is_3digits {
my $val = shift;
my $retval = undef;
$retval=1 if $val =~ /^\d{3}$/;
return $retval;
}
package main;
*main::is_3digits = *Foo::is_3digits;
# delete $Foo::{is_3digits};
is_3digits(1234);
is_3digits(123);