Dynamical loading of modules

[Carsten Haese]

On Mon, 2005-10-03 at 17:37, Steve Holden wrote:
> Carsten Haese wrote:
> > On Mon, 2005-10-03 at 16:41, Carsten Haese wrote:
> > 
> >>On Mon, 2005-10-03 at 15:52, Jacob Kroon wrote:
> >>
> >>>Hi, I'm having some problems with implementing dynamical module loading. 
> >>>First let me
> >>>describe the scenario with an example:
> >>>
> >>>modules/
> >>>    fruit/
> >>>        __init__.py
> >>>        apple.py
> >>>        banana.py
> >>>
> >>>apple.py defines a class 'Apple', banana defines a class 'Banana'. The 
> >>>problem lies in the
> >>>fact that I want to be able to just drop a new .py-file, for instance 
> >>>peach.py, and not change
> >>>__init__.py, and it should automatically pickup the new file in 
> >>>__init__.py. I've come halfway
> >>>by using some imp module magic in __init__.py, but the problem I have is 
> >>>that the instantiated
> >>>objects class-names becomes fruit.apple.Apple/fruit.banana.Banana, whild 
> >>>I want it to be
> >>>fruit.Apple/fruit.Banana.
> >>>
> >>>Is there a smarter way of accomplishing what I am trying to do ?
> >>>If someone could give me a small example of how to achieve this I would 
> >>>be very grateful.
> >>
> >>How about something like this in fruit/__init__.py:
> >>
> >>import os
> >>
> >>fruit_dir = os.path.dirname(__file__)
> >>fruit_files = [x for x in os.listdir(fruit_dir) if (x[-3:]=='.py' and x!='__init__.py')]
> >>for fruit_file in fruit_files:
> >>  module_name = fruit_files[:-3]
> > 
> >                   ^^^^^^^^^^^ This should be fruit_file, of course.
> > 
> > 
> >>  exec "from %s import *" % module_name
> >>
> 
> Wouldn't
> 
>      __import__(module_name)
> 
> be better.

I don't see how a working example that meets the OP's requirements can
be constructed using __import__, but that may easily be due to my lack
of imagination. How would you do it?

Regards,

Carsten Haese.