[Python-Dev] requirements for moving import over to importlib? (original) (raw)

Brett Cannon brett at python.org
Wed Feb 8 17:24:58 CET 2012

On Wed, Feb 8, 2012 at 11:09, Antoine Pitrou <solipsis at pitrou.net> wrote:

Le mercredi 08 février 2012 à 11:01 -0500, Brett Cannon a écrit : > > > On Tue, Feb 7, 2012 at 17:42, Antoine Pitrou <solipsis at pitrou.net> > wrote: > On Tue, 7 Feb 2012 17:24:21 -0500 > Brett Cannon <brett at python.org> wrote: > > > > IOW you want the sys.modules case fast, which I will never > be able to match > > compared to C code since that is pure execution with no I/O. > > > Why wouldn't continue using C code for that? It's trivial > (just a dict > lookup). > > > Sure, but it's all the code between the function call and hitting > sys.modules which would also need to get shoved into the C code. As I > said, I have not tried to optimize anything yet (and unfortunately a > lot of the upfront costs are over stupid things like checking if > import is being called with a string for the module name).

I guess my point was: why is there a function call in that case? The "import" statement could look up sys.modules directly.

Because people like to do wacky stuff with their imports and so fully bypassing import would be bad.

Or the built-in import could still be written in C, and only defer to importlib when the module isn't found in sys.modules. Practicality beats purity.

It's a possibility, although that would require every function call to fetch the PyInterpreterState to get at the cached import (so the proper sys and imp modules are used) and I don't know how expensive that would be (probably as not as expensive as calling out to Python code but I'm thinking out loud). -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.python.org/pipermail/python-dev/attachments/20120208/c459b1d9/attachment-0001.html>

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