Question

In my working python directory I create:

packagename/__init__.py
packagename/modulename.py
test.py

In modulename.py I create some empty class:

class Someclass(object):
   pass

in test.py:

import packagename
packagename.modulename.Someclass()

Why I can’t call packagename.modulename.someclass() in test.py ?

AttributeError: 'module' object has no attribute 'modulename'

I understand that the right way is:

import packagename.modulename

or

from packagename import modulename

But I do not understand why I get this error in my case.

Update:

In other words is there any way to import a package’s content with all modules in the distinct namespace?
I need correct pythonic expression for:

from packagename import * as mynamespace

Answer 1

If you had 100 modules in the “packagename” package, would you want them all to be imported automatically when you imported just the top-level name? That wouldn’t usually be a good idea, so Python doesn’t do it.

If you want to have that particular module imported automatically, just include it in the __init__.py like so:

from packagename import modulename

Alternatively, using Python 2.5 or 2.6:

from __future__ import absolute_import
from . import modulename

(In later versions, you can ditch the from __future__ part.)

Edit: there is no built-in mechanism to ask Python to import all possible submodules inside a package. That’s not a common use case, and it’s better handled explicitly by having your __init__.py import precisely those things that you want. It would be possible to put something together to do the job (using __import__() and such) but it is better in most cases just to explicitly import all submodules as described.