on package import, have it conditionally import a subpackage

[Gabriel Genellina]

En Sat, 19 Sep 2009 17:06:11 -0300, Gabriel Rossetti  
<gabriel.rossetti at arimaz.com> escribió:

> Hello everyone,
>
> I'd like to ba able to import a package and have it's __init__  
> conditionally import a subpackage. Suppose that you have this structure :
>
> mybase/
> mybase/__init__.py
> mybase/mypkg
> mybase/mypkg/__init__.py
> mybase/mypkg/module0.py
> mybase/mypkg/type1
> mybase/mypkg/type1/__init__.py
> mybase/mypkg/type1/module1.py
> mybase/mypkg/type1/module2.py
> mybase/mypkg/type2
> mybase/ mypkg/type2/__init__.py
> mybase/ mypkg/type2/module1.py
> mybase/ mypkg/type2/module2.py
>
> I'd like to do something like th following in my code
>
>  >>> import mybase
>  >>> mybase.setType("type1")
>  >>> from mybase.mypkg import module0, module1, module2
>  >>> module0.__file__
> 'mybase/mypkg/module0.pyc'
>  >>> module1.__file__
> 'mybase/mypkg/type1/module1.pyc'
>  >>> module2.__file__
> 'mybase/mypkg/type1/module2.pyc'
>
> but I can't figure out how to do this.

That depends on how dynamic you want/have to be.

(inside mybase/mypkg.__init__py):

def setType(type_):
   global module1, module2
   if type_ == 'type1':
     from .type1 import module1, module2
   elif type_ == 'type2':
     from .type2 import module1, module2
   else:
     raise ValueError, 'unknown type: %s' % type_

A more generic version:

def setType(type_):
   global module1, module2
   t = __import__(type_, globals(), locals(), ['module1','module2'], 1)
   module1 = t.module1
   module2 = t.module2

-- 
Gabriel Genellina