#!/usr/bin/perl -w

BEGIN {
	if    ( $^O =~ /dar/ ) { use mac }
	elsif ( $^O =~ /sol/ ) { use sun }
	elsif ( $^O =~ /aix/ ) { use aix }
	else                   { die "unknown os." }
};

package main;

print "answer is " . get_answer() . "\n";
exit 0;

package mac;
sub get_answer { return "Apple" }

package sun;
sub get_answer { return "Sun" }

package aix;
sub get_answer { return "IBM" }

__END__