[Python-Dev] an unimportant question, ...

[Thomas Wouters]

On Sun, Mar 22, 2009 at 20:38, Christian Tismer <tismer at stackless.com>wrote:

> On 3/22/09 8:01 PM, "Martin v. Löwis" wrote:
>
>> Now, the internals are very clear to me. What I don't understand
>>> is where the three saved bytes should be.
>>>
>>
>> If you look at the various patches in
>>
>> http://bugs.python.org/issue576101
>>
>> then there is a three-byte saving in all versions from 1 to 6.
>> Consequentially, the API was changed in those versions (but only
>> starting from version 5, i.e. the first version created by Guido).
>>
>> For some reason, the saving was then removed from the patch that
>> got actually committed (#7). I guess the comment just stayed.
>>
>
> Yes, funny, actually. At least, I don't find any comment why
> the char was turned into an int, after all.
> Are char pointers not on a word boundary problematic on some
> platforms?
>
> Or was it maybe to just keep the string layout on many
> common platforms compatible, in order to save rebuilding
> so many windows extension modules?
>
> If the latter is true and the only reason, I vote for reclaiming
> the three bytes. Maybe it saves a tree or two. Maybe it hurts
> very little if done for Python 3000.
>
> In any case, use the version that saves the most energy. :-)
>
> not kidding - ciao -- chris


Actually, we should use the version that breaks the ABI the least. The
change you're referring to actually (comparatively silently!) broke the ABI
for 64-bit Python builds (at least, on LP64 and LLP64 systems, which is most
of them.)  You can normally relatively safely use an extension module built
for Python 2.2 in Python 2.4, but not so for 64-bit builds. Let's try to
keep the ABI compatible, and at least make it an error (not a warning) to
load a truly incompatible ABI version.

-- 
Thomas Wouters <thomas at python.org>

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