[Python-Dev] PEP 420 - dynamic path computation is missing rationale

[PJ Eby]

On Wed, May 23, 2012 at 9:02 PM, Eric V. Smith <eric at trueblade.com> wrote:

> On 5/23/2012 8:58 PM, PJ Eby wrote:
> > On Wed, May 23, 2012 at 8:24 PM, Eric V. Smith <eric at trueblade.com
> > <mailto:eric at trueblade.com>> wrote:
> >
> >     I tried this approach and it works fine. The only caveat is that it
> >     assumes that the parent path can always be computed as described
> above,
> >     independent of what's passed in to PathFinder.load_module(). I think
> >     that's reasonable, since load_module() itself hard-codes sys.path if
> the
> >     supplied path is missing.
> >
> >
> > Technically, PEP 302 says that finders aren't allowed to assume their
> > parent packages are imported:
> >
> > """ However, the find_module() method isn't necessarily always called
> > during an actual import: meta tools that analyze import dependencies
> > (such as freeze, Installer or py2exe) don't actually load modules, so a
> > finder shouldn't /depend/ on the parent package being available in
> > sys.modules."""
> >
> > OTOH, that's finders, and I think we're dealing with loaders here.
> > Splitting hairs, perhaps, but at least it's in a good cause.  ;-)
>
> I guess I could store the passed-in parent path, and use that if it
> can't be found through sys.modules.
>
> I'm not sure I can conjure up code to test this.
>

I actually was suggesting that we change PEP 302, if it became an issue.
;-)
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