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From: lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall)
Newsgroups: comp.lang.perl
Subject: Re: Globbing
Message-ID: <7234@jpl-devvax.JPL.NASA.GOV>
Date: 2 Mar 90 01:12:44 GMT
References: <15209@bfmny0.UU.NET> <100306@convex.convex.com>
Reply-To: lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall)
Organization: Jet Propulsion Laboratory, Pasadena, CA
Lines: 35

In article <100306@convex.convex.com> tchrist@convex.COM (Tom Christiansen) writes:
: Also, I'd love to use /o on a couple things here, but that would
: mean only being able to call the function once.  Any way to invalidate the
: /o thing?  I would like to do a grep(/$expr/o, @args) where the $expr is
: only compiled once per new grep but not at every internal iteration of
: grep, and I don't think it's currently feasible.  That way you could do:
: 
: 	for $expr (@list) {
: 	    for $item (@other_list) {
: 		&foo if $item =~ /$expr/o;
: 	    }
: 	}
: 
: and have the $expr compiled only once per iteration of the outer loop.

You can do it like this:

	for $expr (@list) {
	    eval "#$expr" . '
		for $item (@other_list) {
		    &foo if $item =~ /$expr/o;
		}
	    ';
	}

The purpose of the #$expr is to force recompilation of the otherwise
identical (and hence not recompiled) string.

This may or may not save you time, depending on how long @other_list is.
There is considerable overhead in recompiling each time through the
outer loop.

I could conceivable reset //o at the same time as I reset ?? searches.

Larry