On Sat, 9 Mar 2002, Matthew Cline wrote:
> Why is "(?:" used in the rules regexps instead of just "("?
Because a back-reference to that group is not needed.
> Does the engine that applies the rules put normal parens around the
> whole regexp, and we don't want to interfere with it generating $1, $2
> and such?
I doubt that. :)
> Does "(?:" use less resources?
Yes, substantially in some cases. It's a good optimization for most
regexp engines and, given that Perl was one of the originating places
for it[1], it's undoubtedly helpful there.
Daniel
Footnotes:
[1] At least in popular use.
--
Bargaining is essential to the life of the world;
but nobody has ever claimed that it is an enobling process.
-- Agnes Repplier
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