[Python-ideas] Bytestrings in Python 2

[Serhiy Storchaka]

On 25.04.15 22:27, Markus Unterwaditzer wrote:
> On Sat, Apr 25, 2015 at 07:14:57PM +0300, Serhiy Storchaka wrote:
>> Here is an idea that perhaps will help to prepare Python 2 code for
>> converting to Python 3.
>>
>> Currently bytes is just an alias of str in Python 2, and the "b" prefix of
>> string literals is ignored. There are no differences between natural strings
>> and bytes. I propose to add special bit to str instances and set it for
>> bytes literals and strings created from binary sources (read from binary
>> files, received from sockets, the result of unicode.encode() and
>> struct.pack(), etc). With -3 flag operations with binary strings that
>> doesn't allowed for bytes in Python 3 (e.g. encoding or coercing to unicode)
>> will emit a warning. Unfortunately we can't change the bytes constructor in
>> minor version, it should left an alias to str in 2.7. So the result of
>> bytes() will be not tagged as binary string.
>>
>> May be it is too late for this.
>
> You can get similar kinds of warnings with unicode-nazi
> (https://github.com/mitsuhiko/unicode-nazi), so I'm not sure if this would be
> that helpful.

Not quite. With unicode-nazi 'foo' == u'foo' emits a warning, with my 
proposition it doesn't, but b'foo' == u'foo' does. unicode-nazi should 
produce a lot of warnings in the stdlib and user code, my proposition 
should be more compatible.