Talk:Perl Compatible Regular Expression

From Wikipedia, the free encyclopedia

Shouldn't it be "Perl"?

Shouldn't what be "Perl"?

[edit] Misnomer

From the article:

The name is a misnomer, because Perl's regular expressions permit embedded Perl code during matching and replacing, so to be truly "Perl Compatible" would need a full Perl interpreter embedded in the library. PCRE contains no such interpreter.

Um...it's not a misnomer. The regular expressions of PCRE are compatible with Perl's. Embedded source code does not constitute a "regular expression pattern". 70.20.145.231 19:57, 26 November 2005 (UTC)

No, they're not entirely exactly compatible. Embedded Perl source code is considered part of the regular expression in Perl. PCRE will always do things that Perl can't, and vice versa. Randal L. Schwartz 21:27, 26 November 2005 (UTC)

That's a very silly thing to put in an encyclopaedia article in that way. It sounds like a silly sling against PCRE. Nothing is compatible with anything. Come on. 208.115.233.109 14:47, 23 March 2007 (UTC)

[edit] PCRE_EXTENDED

Need described on article?

See "CONDITIONAL SUBPATTERNS".

[edit] Recursive expressions

To Randal and anyone else interested: we say:

PCRE has developed a unique feature set, which in some cases includes features not yet available even in Perl's regular expression engine. For example, recursive subpatterns will be a feature of an upcoming 2006 release of Perl 5, but are already available in PCRE

Our citation for this is the PCRE manual which says:

Fairly obviously, PCRE does not support the (?{code}) and (??{code}) constructions. However, there is support for recursive patterns. This is not available in Perl 5.8, but will be in Perl 5.10.

This is pretty clear. PCRE doesn't support Perl's inline code ala ?{print "foo"} or ??{$regexp}, but does support recursive subexpressions, a feature which is being added to 5.10. I've been following this in Perl and PCRE, so I'm pretty sure of this. -Harmil 00:09, 14 February 2007 (UTC)

As an example of how PCRE and Perl regex are different, it's a bad example. Perhaps a simpler example that isn't so convoluted to explain would be handy. --Randal L. Schwartz 21:12, 16 February 2007 (UTC)

Ok, rather than trying to expand and clarify the example to the point of distracting from the topic at hand, I've extracted the example and simply put the conclusion in: the development of new features in both languages is coordinated, but unique. I think that sums up the situation, and is supported by the ref, without getting bogged down. I still think that the recursive sub-pattern feature (while it can be emulated by variable or code interpolation via ?{...} and ??{...}) is distinct and unique, but if there's a debate to be had around it, Wikipedia's not the place to have that debate, so I'll stand down. -Harmil 21:33, 16 February 2007 (UTC)