[Python-Dev] Re: pre-PEP: Complete, Structured Regular Expression Group Matching (original) (raw)

Michael Hudson mwh at python.net
Sat Aug 7 16:16:09 CEST 2004

Mike Coleman <mkc at mathdogs.com> writes:

Michael Hudson <mwh at python.net> writes:

Generally, it strikes me as mildly useful. An implementation would surely help :-) If yours is the most positive review, there probably won't be one. :-)

Well, I thought someone should say something, just to stop the proto-pep being lost. Have you sent it to the PEP editor yet? I think it's ready enough.

The reason that I only said "mildly useful" was because I didn't think "OMG! I would so have liked to use this yesterday" or anything like that...

Seriously, though, I'd readily concede that there are different approaches to solving this problem, and I was hoping for some feedback and suggestions before I start whacking at the code. I also have considered the possibility that although this has been driving me nuts that few others will care--if this is true, it probably shouldn't go in the core libraries.

It depends a bit on whether it can be implemented as an addition in a non-painful way, or whether editing the sre code makes it very much easier. I don't know the answer, mind.

[mismatch index return] I don't really like this idea; it seems to be that it would be more helpful to raise an exception and attach this data to the exception. But that's a bit inconsisent with how match and search work. Hmm. Yeah, if it weren't for the value of matching re.match semantics, it would make a lot more sense for this to be an exception. As it is, I could see it going either way.

I think you could make a case for raising an exception; the point of structmatch is to extract information, whereas at least sometimes you call re.match just to see if the data matches the pattern.

Or I suppose you could add a flag to determine which (but ugh).

Err, let's not go there.

Cheers, mwh

-- Lisp nearing the age of 50 is the most modern language out there. GC, dynamic, reflective, the best OO model extant including GFs, procedural macros, and the only thing old-fashioned about it is that it is compiled and fast. -- Kenny Tilton, comp.lang.python

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