[Python-Dev] What to do for bytes in 2.6?

[Aahz]

On Sat, Jan 19, 2008, Guido van Rossum wrote:
>
> I believe that a constraint should be that by default (without -3 or a
> __future__ import) str and bytes should be the same thing. Or, another
> way of looking at this, reads from binary files and reads from sockets
> (and other similar things, like ctypes and mmap and the struct module,
> for example) should return str instances, not instances of a str
> subclass by default -- IMO returning a subclass is bound to break too
> much code. 

This makes perfect sense to me.  And yet, I also like the idea that
b""+u"" raises an exception.  I have a suggestion, then: for 2.6, let's
make bytes a subclass of string whose only difference is that it contains
a flag.  I don't care whether b""+u"" raises an exception.  This should
be enough for people on an accelerated 3.0 conversion schedule, and they
can write their own test for the flag if they care.

For 2.7, we can start tightening up.  b""+u"" can raise an exception,
and the socket module might use a RETURN_BYTES variable.

To put it another way, I don't think we should consider 2.6 the stopping
point for 2.x/3.x conversion help.  There's nothing wrong with planning
for features to go into 2.7 -- just as several PEPs in the past have had
multi-version planning.
-- 
Aahz (aahz at pythoncraft.com)           <*>         http://www.pythoncraft.com/

"All problems in computer science can be solved by another level of     
indirection."  --Butler Lampson