On 17 December 2016 at 21:58, Serhiy Storchaka <storch...@gmail.com> wrote:
> On 17.12.16 13:44, Christian Heimes wrote: > >> On 2016-12-17 10:06, Serhiy Storchaka wrote: >> >>> On 16.12.16 21:24, Guido van Rossum wrote: >>> >>>> e.g. the argument to getattr() -- I still hear of code that breaks due >>>> to this occasionally) >>>> >>> >>> What is the problem with unicode in getattr()? Unicode attribute name is >>> converted to str, and since the result is cached, this even don't add >>> much overhead. >>> >> >> It breaks the str optimization of dicts. Dict with str-only keys are >> special-cased in Python 2. >> > > getattr() converts a unicode to str and passes a str to PyObject_GetAttr(). getattr() may do the right thing, but directly accessing __dict__ doesn't. python-future has a good write-up of the benefits and drawbacks, as they originally recommended it unconditionally when modernising code, and myself, Armin Ronacher, and a few others convinced them to be a little more judicious in suggesting it to people: http://python-future.org/unicode_literals.html However, that page also points out that whether or not it's likely to help more than it hurts depends a lot on which version of Python you're starting from: - if you're making originally Python 3 only code also work on Python 2, and hence defining the first ever version of its Python 2 API, then you probably *do* want to use unicode_literals, and then explicitly mark bytes literals to get Python 2 working - if you're modernising Python 2 code and have a lot of existing API users on Python 2, then you probably *don't* want to use unicode_literals, and instead explicitly mark your text literals as Unicode to get Python 3 working In cases like Django where folks successfully adopted the "unicode_literals" import for modernisation purposes, it was a matter of aiming to get to that "Python 3 native, with Python 2 also supported" structure as soon as possible (the fact that Django is structured primarily as an object oriented framework likely helped with that, as it has a lot of control over the data types user applications end up encountering). Cheers, Nick. -- Nick Coghlan | ncogh...@gmail.com | Brisbane, Australia
_______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
