[Python-Dev] Using PEP384 Stable ABI for the lzma extension module

[Antoine Pitrou]

On Tue, 04 Oct 2011 21:33:34 +0200
"Martin v. Löwis" <martin at v.loewis.de> wrote:
> Am 04.10.11 21:06, schrieb Amaury Forgeot d'Arc:
> > 2011/10/4 "Martin v. Löwis"<martin at v.loewis.de>:
> >>
> >>> - _PyBytes_Resize() is missing; I moved it under a Py_LIMITED_API
> >>>    section.
> >>
> >> ??? Are you proposing to add _PyBytes_Resize to the Py_LIMITED_API
> >> set of functions? It's not even an API function in the first place
> >> (it starts with an underscore), so how can it be a limited API function?
> >
> > It's not a proposal of any kind; it's just the workaround I used to compile
> > and test.
> > OTOH, it seems that many modules already use this function. Is there
> > another method that does not need to copy data?
> 
> Not sure what you are using it for. If you need to extend the buffer
> in case it is too small, there is absolutely no way this could work
> without copies in the general case because of how computers use
> address space. Even _PyBytes_Resize will copy the data.

That's not a given. Depending on the memory allocator, a copy can be
avoided. That's why the "str += str" hack is much more efficient under
Linux than Windows, AFAIK.

Regards

Antoine.