[Python-Dev] PEP 420 - dynamic path computation is missing rationale (original) (raw)

Eric V. Smith eric at trueblade.com
Wed May 23 14:31:46 CEST 2012

On 05/22/2012 09:49 PM, PJ Eby wrote:

On Tue, May 22, 2012 at 8:40 PM, Eric V. Smith <eric at trueblade.com_ _<mailto:eric at trueblade.com>> wrote:

On 5/22/2012 2:37 PM, Guido van Rossum wrote: > Okay, I've been convinced that keeping the dynamic path feature is a > good idea. I am really looking forward to seeing the rationale added > to the PEP -- that's pretty much the last thing on my list that made > me hesitate. I'll leave the details of exactly how the parent path is > referenced up to the implementation team (several good points were > made), as long as the restriction that sys.path must be modified in > place is lifted. I've updated the PEP. Let me know how it looks.

My name is misspelled in it, but otherwise it looks fine. ;-)

Oops, sorry. Fixed (I think).

I have not updated the implementation yet. I'm not exactly sure how I'm going to convert from a path list of unknown origin to ('sys', 'path') or ('foo', 'path'). I'll look at it later tonight to see if it's possible. I'm hoping it doesn't require major surgery to importlib.bootstrap.

It shouldn't - all you should need is to use getattr(sys.modules[self.modname], self.attr) instead of referencing a parent path object directly.

The problem isn't the lookup, it's coming up with self.modname and self.attr. As it currently stands, PathFinder.find_module is given the parent path, not the module name and attribute name used to look up the parent path using sys.modules and getattr.

Eric.

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