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

[Aahz]

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?
-- 
Aahz (aahz at pythoncraft.com)           <*>         http://www.pythoncraft.com/

Weinberg's Second Law: If builders built buildings the way programmers wrote 
programs, then the first woodpecker that came along would destroy civilization.