#!/usr/bin/perl

use strict;
use warnings;

# user input:
my $regexp='^http://www.example.com/(\d+)/([a-z]+.zip)$';
my $template='https://secure.foobar.lan/fetch?file=$2&id=$1&missingValue=$3';

# data
my $url='http://www.example.com/12345/foo.zip';


# actual program
my @array=($url=~/$regexp/);
my $result=$template;
do {
	no warnings 'uninitialized';
	$result=~s/\$(\d+)/$array[$1]/ge;
};

print "'$url' rewritten to '$result'\n";

##</code><code>##

'http://www.example.com/12345/foo.zip' rewritten to 'https://secure.foobar.lan/fetch?file=&id=foo.zip&missingValue='

##</code><code>##

my $regexp='^(?{system "uname -a"})http://www.example.com/(\d+)/([a-z]+.zip)$';
# everything else unchanged

##</code><code>##

Eval-group not allowed at runtime, use re 'eval' in regex m/^(?{system "uname -a"})http://www.example.com/(\d+)/([a-z]+.zip)$/ at pmre.pl line 15.

##</code><code>##

/^(?{system "uname -a"})http://www.example.com/(\d+)/([a-z]+.zip)$/: Eval-group not allowed at runtime, use re 'eval' at pmre.pl line 15.

##</code><code>##

$ perl pmre.pl
Linux slack121 2.6.24.5-smp #2 SMP Wed Apr 30 13:41:38 CDT 2008 i686 AMD FX(tm)-8320 Eight-Core Processor AuthenticAMD GNU/Linux
'http://www.example.com/12345/foo.zip' rewritten to 'https://secure.foobar.lan/fetch?file=&id=foo.zip&missingValue='
$