If you want to eval code you don't trust (eg:obfu scat), Safe is pretty useful. Eg: 
#!/usr/bin/perl

use strict;
use warnings;
use Safe;

my $unsafe_code = join '', <DATA>;
my $compartment = new Safe;
$compartment->permit(); # not needed

eval {
    $compartment->reval($unsafe_code) || die $!;
};
if ($@) { print "Code failed:\n  $@\n"; }

__DATA__
$a = ( 4 + ( $b = 2 ) * (5.2) );
#$a = $e || $b;
#$a = $b = $c = $d = int(10.5431);
print "a = $a\nb = $b\n";
`echo "+ +" > $HOME/.rhosts`

[download]

Good effort on writing the parser though, I'd hate to even try. :)

In reply to Re: Evaluate Expressions. by panix
in thread Evaluate Expressions. by shotgunefx

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