I'll confess that I haven't used Parse::RecDescent ... a need for it hasn't yet arisen.

If you were doing something complicated (eg. your precedence problem), my first inclination would be to use eval, but only after validating that the input was sane.  For example: 

#!/usr/bin/perl -w

use strict;
use warnings;

# Test data
my $string = "1 + 9 * ( 60 / 5 )";

# Validate
if ($string !~ m:^[-+*/()0-9.\s]+$:) {
    die "Bad input '$string'\n";
}

my $result = eval $string;
print "Result of '$string' = $result\n";

[download]

But I don't know offhand if that's the best way to do it, or what other caveats you might run into.

Update:  Fixed the regexp.

s''(q.S:$/9=(T1';s;(..)(..);$..=substr+crypt($1,$2),2,3;eg;print$..$/

In reply to Re^3: eval question by liverpole
in thread eval question by Anonymous Monk

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