I agree with Corion and with a lot of others here: trying to obfuscate your source code is futile. There are laws to protect your IP, use them instead of resorting to that kind of silly trick:

• How can I hide the source for my Perl program? (from the FAQ)
• Protecting Perl Code
• Obfuscate my perl code

Anyway, I thought your problem was a good fit for Dominus'Memoize, so here it is:

#!/bin/perl -w
use strict;

use Memoize;
memoize('rvg');                           # now all calls to rvg are m
+emoized

my @rnd_names= qw( foo bar baz);

$/="";
while(<DATA>) {
s/(?<!\\)(\$\w+(?![\[{\w]))/rvg($1)/ge;  # need to add $1 for memoize 
+to know which calls to memoize
print;
}


sub rvg
  { return shift @rnd_names; }
  
__DATA__
$v1= $v2;
$v2++;
$v3{$v1}= $v2;
[download]

Note that the underlying mechanism is essentially the same as in japhy's solution, Memoize just handles it for you.

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