On Sun, Oct 5, 2008 at 11:43 PM, Steve Holden <[EMAIL PROTECTED]> wrote: > This does make it look rather as though bytes == str was a decision > whose consequences weren't fully appreciated before implementation. > > Was this horror anticipated?
It was well understood that the bytes "type" in 2.6 and the bytes type in 3.0 would behave quite different. Attempts to come up with a separate bytes type that behaved more like its 3.0 counterpart were doomed, because there just are too many places where the usage was ambiguous. We should probably have written a PEP about this just to prevent the discussion from being repeated all over again in this thread. The only two anticipated *reasonable* uses in 2.6 were the bytes literal (b'abc') and tests for isinstance(x, bytes), which are flags for 2to3 to keep these usages as bytes, not str. I have no intention of rolling this back. It isn't compatible with 3.0, but then, 2.6 and 3.0 aren't in general meant to be compatible -- 2.6 is a stepping stone, but that's not the same thing. It is backwards compatible with prior versions because it is new in 2.6, so it shouldn't break old code. I have only limited sympathy for people who don't read documentation in this case. --Guido > -------- Original Message -------- > Subject: In Python 2.6, bytes is str > Date: Sun, 05 Oct 2008 22:30:17 -0700 > From: Bryan Olson <[EMAIL PROTECTED]> > Organization: at&t http://my.att.net/ > To: [EMAIL PROTECTED] > Newsgroups: gmane.comp.python.general > > > Python 3 has the 'bytes' type, which the string type I've long wanted in > various languages. Among other advantages, it is immutable, and > therefore bytes objects can be dict keys. There's a mutable version too, > called "bytearray". > > In Python 2.6, the name 'bytes' is defined, and bound to str. The 2.6 > assignment presents some pitfalls. Be aware. > > Consider constructing a bytes object as: > > b = bytes([68, 255, 0]) > > In Python 3.x, len(b) will be 3, which feels right. > > In Python 2.6, len(b) will be 12, because b is the str, '[68, 255, 0]'. > > > I'm thinking I should just avoid using 'bytes' in Python 2.6. If there's > another Python release between 2.6 and 3.gold, I'd advocate removing > the pre-defined 'bytes', or maybe defining it as something else. > > > -- > --Bryan > -- > http://mail.python.org/mailman/listinfo/python-list > > > -- > Steve Holden +1 571 484 6266 +1 800 494 3119 > Holden Web LLC http://www.holdenweb.com/ > > _______________________________________________ > 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/guido%40python.org > -- --Guido van Rossum (home page: http://www.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
