Ok, created http://bugs.python.org/issue18468.
On Mon, Jul 15, 2013 at 4:30 PM, Gregory P. Smith <g...@krypto.org> wrote: > > On Mon, Jul 15, 2013 at 4:14 PM, Guido van Rossum <gu...@python.org> wrote: >> >> In a discussion about mypy I discovered that the Python 3 version of >> the re module's Match object behaves subtly different from the Python >> 2 version when the target string (i.e. the haystack, not the needle) >> is a buffer object. >> >> In Python 2, the type of the return value of group() is always either >> a Unicode string or an 8-bit string, and the type is determined by >> looking at the target string -- if the target is unicode, group() >> returns a unicode string, otherwise, group() returns an 8-bit string. >> In particular, if the target is a buffer object, group() returns an >> 8-bit string. I think this is the appropriate behavior: otherwise >> using regular expression matching to extract a small substring from a >> large target string would unnecessarily keep the large target string >> alive as long as the substring is alive. >> >> But in Python 3, the behavior of group() has changed so that its >> return type always matches that of the target string. I think this is >> bad -- apart from the lifetime concern, it means that if your target >> happens to be a bytearray, the return value isn't even hashable! >> >> Does anyone remember whether this was a conscious decision? Is it too >> late to fix? > > > Hmm, that is not what I'd expect either. I would never expect it to return a > bytearray; I'd normally assume that .group() returned a bytes object if the > input was binary data and a str object if the input was unicode data (str) > regardless of specific types containing the input target data. > > I'm going to hazard a guess that not much, if anything, would be depending > on getting a bytearray out of that. Fix this in 3.4? 3.3 and earlier users > are stuck with an extra bytes() call and data copy in these cases I guess. > > -gps > -- --Guido van Rossum (python.org/~guido) _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
