[Python-Dev] regex module (original) (raw)

MRAB python at mrabarnett.plus.com
Wed Jan 13 04:09:34 CET 2010

MRAB wrote:

Hi all,

I'm back on the regex module after doing other things and I'd like your opinion on a number of matters: Firstly, the current re module has a bug whereby it doesn't split on zero-width matches. The BDFL has said that this behaviour should be retained by default in case any existing software depends on it. My question is: should my regex module still do this for Python 3? Speaking personally, I'd like it to behave correctly, and Python 3 is the version where backwards-compatibility is allowed to be broken. Secondly, Python 2 is reaching the end of the line and Python 3 is the future. Should I still release a version that works with Python 2? I'm thinking that it could be confusing if new regex module did zero-width splits correctly in Python 3 but not in Python 2. And also, should I release it only for Python 3 as a 'carrot'? Finally, the module allows some extra backslash escapes, eg \g, in the pattern. Should it treat ill-formed escapes, eg \g, as it would have treated them in the re module? I've just noticed something odd about the re module: the sub() method doesn't take 'pos' or 'endpos' arguments. search() does; match() does; findall() does(); finditer() does; but sub() doesn't. Maybe there has never been a demand for it. (Nor split(), for that matter.)

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