[Python-Dev] public visibility of python-dev decisions "before it's too late"

[Stefan Behnel]

Eric Smith, 16.03.2011 04:12:
> On 3/15/2011 10:58 PM, Lennart Regebro wrote:
>> On Tue, Mar 15, 2011 at 22:42, Guido van Rossum wrote:
>>> Fortunately there may not be any more such cases since no new major
>>> versions of Python 2 will be released. So I'm not sure what an update
>>> of PEP 5 will buy us.
>>
>> That is a good point. But at least making sure no more API's get
>> deprecated in 3.3 (and preferably 3.4) would go a long way, as we are
>> likely to still have to support Python 2 in parallell for those
>> versions as well.
>
> I think it's valid that we should consider the affect of libraries that are
> trying to support 2.x and 3.y (for some values of x and y) at the same
> time.

I don't really see any for this specific change, though. It's not an issue 
of supporting "both 2.x and 3.x", it's an issue of supporting 3.2 and 
earlier CPython versions, and it's not even hard to do that. Basically, you 
can copy&adapt code from a project that already supports it and be done.

CPython has broken backwards compatibility in certain areas more than once. 
It even broke basically all existing C code in 2.5 with the introduction of 
Py_ssize_t (well, technically, it didn't break it on 32bit platforms, but 
it introduced a pretty heavy push for people to walk through their code and 
manually adapt it anyways). Other breakages had a much smaller impact than 
that. If the amount of affected code is smaller, it's unfortunate to be 
amongst those who are hit by such a change, but if there's a reason to go 
that route, well, then there's a reason.

I still consider this is mostly a communication issue. If this change had 
been properly written up, preferably in a PEP, including the reasoning for 
it to get done, I think this whole discussion would not have been necessary.

Stefan