precompiling regexes

bless$self=>perlmonks; has asked for the wisdom of the Perl Monks concerning the following question:

I have a bunch of regular expressions in a text file that is frequently read, but infrequently changed. I want to compile all of the regexes, and store them in another file. I tried doing this like so:

$re = qr/$foo/;
print FILE $re, "\n";
# ... and at a later time ...
$re = <FILE>
chomp $re;
if($line =~ /$re/) { # blah blah blah....
[download]

and this appears to work. My only question is this: Am I truely saving CPU time by doing this, or does perl still have to do something special to turn that string I got from a file into a regular expression.

Comment on precompiling regexes Download Code

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Re: precompiling regexes by japhy (Canon) on Aug 31, 2001 at 05:52 UTC
The magic is only there for `qr//`'ed regexes. If you read it from the file, it's just a string. You'll have to re-`qr//` it for any gains. But I think you're wasting effort on this. Maybe not. _____________________________________________________ Jeff`[japhy]`Pinyan: Perl, regex, and perl hacker. `s++=END;++y(;-P)}y js++=;shajsj<++y(p-q)}?print:??;`	[reply]