[Python-Dev] __file__

[Floris Bruynooghe]

On Sun, Feb 28, 2010 at 02:51:16PM +1300, Greg Ewing wrote:
> Floris Bruynooghe wrote:
> >(But even then I'm not
> >convinced that would double the stat calls for normal users, only for
> >those who only ship .pyc files)
> 
> It would increase the number of stat calls for normal
> users by 50%. You would need to look for a .pyc in the
> source directory, then .py in the source directory and
> .pyc in the cache directory. That's compared to two
> stat calls currently, for .py and .pyc.

Can't it look for a .py file in the source directory first (1st stat)?
When it's there check for the .pyc in the cache directory (2nd stat,
magic number encoded in filename), if it's not check for .pyc in the
source directory (2nd stat + read for magic number check).  Or am I
missing a subtlety?


> A solution might be to look for the presence of the
> cache directory, and only look for a .pyc in the source
> directory if there is no cache directory. Testing for
> the cache directory would only have to be done once
> per package and the result remembered, so it would
> add very little overhead.

That would work too, but I don't understand yet why the .pyc check in
the source directory can't be done last.

Regards
Floris

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