[Python-Dev] PEP 414 - Unicode Literals for Python 3 (original) (raw)

Chris McDonough chrism at plope.com
Mon Feb 27 22:16:39 CET 2012

On Mon, 2012-02-27 at 21:03 +0000, Vinay Sajip wrote:

Chris McDonough <chrism plope.com> writes:

> I really don't know how long I'll need to do future development in the > subset language of Python 2 and Python 3 because I can't predict the > future. It could be two years, it might be five. Who knows. > > But I do know that I'm going to be developing in the subset of Python > that currently runs on Python 2 >= 2.6 and Python 3 >= 3.2 for at least > a year. And that will suck, because that language is a much less fun > language in which to develop than either Python 2 or Python 3. Frankly, > it's a pretty bad language. What exactly is it that makes it so bad? Since you're developing for >= 2.6, what stops you from using "from future import unicodeliterals" and 'xxx' for text and b'yyy' for bytes? Then you would be working in essentially Python 3.x, at least as far as string literals go. The conversion time will be very small compared to the year time-frame you're talking about. > If we make this change now, it means a year from now I'll be able to > develop in a slightly less sucky subset language if I choose to drop > support for 3.2. And people who don't try to support Python 3 at all > til then will never have to program in the suckiest subset like I will > have had to. And if we don't make the change now and you change your code to use unicodeliterals, convert u'xxx' -> 'xxx' and then change the places where you really meant to use bytes, that'll be a one-off change after which you will be working on a common codebase which works on 2.6+ and 3.0+, and as far as string literals are concerned you'll be working in the hopefully non-sucky 3.x syntax. > Note that u'' literals are sort of the tip of the iceberg here; > supporting them will obviously not make development under the subset an > order of magnitude less sucky, just a tiny little bit less sucky. There > are other extremely annoying things, like str(bytes) returning the repr > of a bytestring on Python 3. That's almost as irritating as the absence > of u'' literals, but we have to evaluate one thing at a time. Yes, but making a backward step like reintroducing u'' just to make things a tiny little bit sucky doesn't seem to me to be worth it, because then >= 3.3 is different to 3.2 and earlier. Armin's suggestion of an install-time fixer is analogous to running 2to3 after every change, if you're trying to support 3.2 and 3.3+ at the same time, isn't it? You can't just edit-and-test, which to me is the main benefit of a single codebase.

The downsides of a unicode_literals future import are spelled out in the PEP:

http://www.python.org/dev/peps/pep-0414/#rationale-and-goals

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