[Python-Dev] PEP: Lazy module imports and post import hook

[glyph at divmod.com]

On 01:09 am, andrew-pythondev at puzzling.org wrote:
>Neal Becker wrote:
>>Christian Heimes wrote:
>>
>> > I've attached the first public draft of my first PEP. A working 
>>patch
>> > against the py3k branch is available at 
>>http://bugs.python.org/issue1576
>> >
>> > Christian
>>
>>Note also that mercurial has demandimport
>>http://www.selenic.com/mercurial/wiki/
>
>And that bzr has lazy_import (inspired by mercurial's demandimport):

and very recently, I implemented similar functionality myself (though it 
isn't in use in Twisted yet):

    http://codebrowse.launchpad.net/~glyph/+junk/pyexport/files

Something that I notice about every other implementation of this 
functionality is that they're all in Python.  But the proposed 
implementation here is written in C, and therefore more prone to 
crashing bugs.  Looking at the roundup log, I can see that several 
refcounting bugs have already been found and fixed.  Perhaps the post- 
import hooks, being a modification to the import mechanism itself, needs 
to be in C, but given that lazy imports *have* been implemented before 
without using C code (and without post import hooks), I can't see why 
they need to be in the same PEP.

Also, as is my custom, I'd like to suggest that, rather than designing 
something new, one of the third-party implementations be adopted (or at 
least its interface) since these have been demonstrated to work in real 
application code already.  Happily, I can escape the charge of bias this 
time since I don't think my own implementation should be taken seriously 
in this case :).