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

Edward Loper edloper at gradient.cis.upenn.edu
Sat Aug 7 03:01:47 CEST 2004

Michael Hudson wrote:

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

Mike wrote:

If yours is the most positive review, there probably won't be one. :-)

I wouldn't lose heart over the lack of response -- the current flood of decorator messages tends to drown out everything else.

I like your idea in the abstract, but I have trouble following many of the examples in your pre-pep (and as a result, I'm not sure if I really understand what you're proposing). E.g., you have:

| >>> m1 = re.match(r'("([A-Z]|[a-z])"\s)*', '"Xx" "yy" "ZzZ"') | >>> m1.group(2) | [['X', 'x'], ['yy'], ['ZzZ']]

But it seems to me like the output should instead be:

| [['X', 'x'], ['y', 'y'], ['Z', 'z', 'Z']]

In particular, group two is "([A-Z]|[a-z])", which matches a single character; so it seems like the value of m1.group(2) should be a tree with leaves that are single characters. (Looking at it from another angle, I can't see any difference between "Xx" and "ZzZ" that would cause one to be decomposed and the other to be left as a string.)

Similar comments apply for many of your other examples. So either:

If it's the former, then please fix the examples. If not, then perhaps we can talk about your algorithm some more off-list, so I can try to see where my misunderstanding is coming from.

-Edward

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