[Python-Dev] Choosing a best practice solution for Python/extension modules

[Brett Cannon]

On Sat, Feb 21, 2009 at 15:46, Aahz <aahz at pythoncraft.com> wrote:

> On Sat, Feb 21, 2009, Brett Cannon wrote:
> >
> > I am seeing two approaches emerging. One is where pickle contains all
> > Python code and then uses something like use_extension to make sure
> > the original Python objects are still reachable at some point. This
> > has the drawback that you have to use some function to make the
> > extensions happen and there is some extra object storage.
> >
> > The other approach is having pickle contain code known not to
> > be overridden by anyone, import _pypickle for stuff that may be
> > overridden, and then import _pickle for whatever is available. This
> > approach has the perk of using a standard practice for how to pull in
> > different implementation. But the drawback, thanks to how globals are
> > bound, is that any code pulled in from _pickle/_pypickle will not be
> > able to call into other optimized code; it's a take or leave it once
> > the call chain enters one of those modules as they will always call
> > the implementations in the module they originate from.
>
> To what extent do we care about being able to select Python-only on a
> per-module basis, particularly in the face of threaded imports?  That is,
> we could have a sys.python_only attribute that gets checked on import.
> That's simple and direct, and even allows per-module switching if the
> application really cares and import doesn't need to worry about threads.
>
> Alternatively, sys.python_only could be a set, but that gets ugly about
> setting from the application.  (The module checks to see whether it's
> listed in sys.python_only.)
>
> Maybe we should move this discussion to python-ideas for now to kick
> around really oddball suggestions?


This is all about testing. If a change is made to some extension code it
should be mirrored in the Python code and vice-versa.

-Brett
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