#!perl
#
# This file is part of String-Substitution
#
# This software is copyright (c) 2010 by Randy Stauner.
#
# This is free software; you can redistribute it and/or modify it under
# the same terms as the Perl 5 programming language system itself.
#

use strict;
use warnings;
use String::Substitution -copy;

my @names = qw(string pattern replacement);
my %vars;

foreach my $name ( @names ){
	# get value from command line or prompt
	if( !($vars{$name} = shift @ARGV) ){
		print "\u$name: ";
		chomp($vars{$name} = <STDIN>);
	}
}

print " '$vars{string}' =~ s/$vars{pattern}/$vars{replacement}/g\n",
	gsub(@vars{ @names }),
	"\n";