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

Michael Hudson mwh at python.net
Fri Aug 6 16:36:11 CEST 2004

Mike Coleman <mkc at mathdogs.com> writes:

If you've ever been frustrated that there wasn't an easy way to parse a string or file, even though you could easily match it with re.match, then this PEP may be for you. If what's being proposed seems a little ghastly, well, I'll just say that I've been wanting something like this for a long time and this is the best I could come up with. Your comments invited.

Generally, it strikes me as mildly useful. An implementation would surely help :-)

Presumably 'structmatch' would also become a metho on pattern objects?

Additional Features -------------------

In many cases in which 're.structmatch' fails to match, the cause will be due to an unexpected error in the format of the string being matched. In order to assist the calling program in generating a more meaningful possible error message, 're.structmatch' will return the endpoint of the largest match against the searched string. So, for example :: re.structmatch('abcd', 'abxxx') --> 2 re.structmatch('abcde|z', 'abxxx') --> 2 re.structmatch('x*?y', 'xxx') --> 3 (This return value should be considered advisory rather than exact, as future improvements in the match algorithm may make it difficult to calculate the exact value.)

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.

Cheers, mwh

-- I have a cat, so I know that when she digs her very sharp claws into my chest or stomach it's really a sign of affection, but I don't see any reason for programming languages to show affection with pain. -- Erik Naggum, comp.lang.lisp

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