Three ways in order of increasing difficulty

• Use regex objects: print qr/(?:this)(?!didn't)match/
• Use the debug mode of the 're' module. use re 'debug';/(?:this)(?!didn't)match/
• Use Dominus' Rx module.

I list the Rx module last because when I last looked at it I it required patching first. Its also probably the one you want to use if you are serious about this.

Thanks for the pointers. I don't mind using YAPE at all, just not sure if there are any gotchas I should look for. I don't intend for my use to serialize these or otherwise store them, just simply add them to the program source for the projects where I don't want the overhead.

-Lee

"To be civilized is to deny one's nature."

Oh I see. Well YAPE doesn't cover all of regex-dom you'll be safe as long as you stick to the YAPE-subset of supported regex constructs. I only gave you advice for solving the more general "decompile a regex" problem. YAPE partially solves the problem "parse a regex" which is quite different and eventually devolves to "parse perl".

    use Regexp::Common qw /number URI/;
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only loads the number and URI patterns. Currently, there are 11 different classes.

From your post, I didn't get any idea what you mean by "getting the source form of a regex" in relation to Regexp::Common, nor what YAPE::Regex::Explain is doing for you.

Abigail

My question I'm sure could have been phrased better. Basically what I was thinking is there are certain times when you might want to use an expression without requiring the module. (Normally I would just want to stick with "use"ing it and getting the benefit of the module's maintainence), so I was curious if there was a way to go from a compiled expression to something I could add to a script without requiring the module for the one regex.

A simple example but if I wanted a pattern to match a real but didn't want to require Regexp::Common I could do something like this.

#!/usr/bin/perl
use warnings;
use strict;

use Regexp::Common qw/number/;
use YAPE::Regex::Explain;

print YAPE::Regex::Explain->new($RE{num}{real})->explain();
__END__
The regular expression:

(?-imsx:(?:(?i)(?:[+-]?)(?:(?=[0123456789]|[.])(?:[0123456789]*)(?:(?:
+[.])(?:[0123456789]{0,}))?)(?:(?:[E])(?:(?:[+-]?)(?:[0123456789]+))|)
+))

matches as follows:
  
NODE                     EXPLANATION
------------------------------------------------------------BLAH BLAH 
+BLAH
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and just add

$thing=~/(?-imsx:(?:(?i)(?:[+-]?)(?:(?=[0123456789]|[.])(?:[0123456789
+]*)(?:(?:[.])(?:[0123456789]{0,}))?)(?:(?:[E])(?:(?:[+-]?)(?:[0123456
+789]+))|)))
/
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to my code.

Which seems like it works but as regex's are my weakest Perl strength, I didn't know if this is a any caveats (things known not to work) with this approach or if there is a more reliable way of doing it. Obviously "cutting and pasting" is a bad idea without total understanding is in general though as far as regexes, I'm willing to put stock in a few monks work (yourself included), but I didn't know if there was anything inherently wrong with the approach.

-Lee

"To be civilized is to deny one's nature."

That's like going from London to Greenwhich via Sydney. Why not just:

    perl -MRegexp::Common -wle 'print $RE{num}{real}'
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Note that this (or the YAPE::) approach doesn't work with recursive regexps.

Abigail