Module name does not match file name

[Peter Otten]

Steven D'Aprano wrote:

> Ah, I think I have a partial answer... but not a complete answer.
> 
> 
> On Mon, 07 Jul 2014 07:57:21 +0000, Steven D'Aprano wrote:
> 
>> Can anyone explain how "import pg" can end up coming from pgmodule.so?
>> 
>> 
>> Sure enough:
>> 
>>>>> import pg
>>>>> pg.__file__
>> '/usr/local/lib/python2.6/dist-packages/pgmodule.so'
> 
> 
> 
> I've looked inside the pgmodule.c source code, and it includes this
> snippet:
> 
> 
> extern void
> initpg(void)
> {
>     char *p;
>     int i;
> 
>     Py_InitModule("pg", pg_methods);
> 
> 
> which suggests that the pgmodule.so file creates a module called "pg".
> What I don't understand is how "import pg" gets turned into "run
> pgmodule.so"?

It seems the suffix "module.so" is tried automagically by the import 
machinery:

$ touch alphamodule.so
$ python
Python 2.7.5+ (default, Feb 27 2014, 19:37:08) 
[GCC 4.8.1] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import alpha
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: ./alphamodule.so: file too short