[Python-Dev] Restricted API versioning

["Martin v. Löwis"]

On 23.06.2012 23:41, Antoine Pitrou wrote:
> On Sat, 23 Jun 2012 23:31:07 +0200
> "Martin v. Löwis" <martin at v.loewis.de> wrote:
>> I've been thinking about extensions to the stable ABI. On the one hand,
>> introducing new API can cause extension modules not to run on older
>> Python versions. On the other hand, the new API may well be stable in
>> itself, i.e. remain available for all coming 3.x versions.
>>
>> As a compromise, I propose that such API can be added, but extension
>> authors must explicitly opt into using it. To define their desired
>> target Python versions, they need to set Py_LIMITED_API to the
>> hexversion of the first Python release they want to support.
> 
> Perhaps something more user-friendly than the hexversion?

Please propose something. I think the hexversion *is* user-friendly,
since it allows easy comparisons (Py_LIMITED_API+0 >= 0x03030000).
Users that run into missing symbols will, after inspection of the
header file, easily know what to do.

We could require a second macro, but users will already have to define
Py_LIMITED_API, so not making them define a second macro is also more
friendly.

Plus, with the hexversion, we can add stuff to a bugfix release, such
a annoying omissions (e.g. the omission of the _SizeT functions, which
I missed since I didn't compile the headers with PY_SSIZE_T_CLEAN when
generating the function list).

Regards,
Martin