Python Import Precedence – Packages vs Modules

Packages will be imported before modules. Illustrated:

% tree .
.
|-- foo
|   |-- __init__.py
|   `-- __init__.pyc
`-- foo.py

foo.py:

% cat foo.py 
print 'you have imported foo.py'

foo/__init__.py:

% cat foo/__init__.py
print 'you have imported foo/__init__.py'

And from interactive interpreter:

>>> import foo
you have imported foo/__init__.py

I have no idea where this is officially documented.

Edit per comment: This was performed with Python 2.7 on Mac OS X 10.6.7. I also performed this using Python 2.6.5 on Ubuntu 10.10 and experienced the same result.

You seem to be misunderstanding how import searches for modules. When you use an import statement it always searches the actual module path (and/or sys.modules); it doesn't make use of module objects in the local namespace that exist because of previous imports. When you do:

import package.subpackage.module
from package.subpackage import module
from module import attribute1

The second line looks for a package called package.subpackage and imports module from that package. This line has no effect on the third line. The third line just looks for a module called module and doesn't find one. It doesn't "re-use" the object called module that you got from the line above.

In other words from someModule import ... doesn't mean "from the module called someModule that I imported earlier..." it means "from the module named someModule that you find on sys.path...". There is no way to "incrementally" build up a module's path by importing the packages that lead to it. You always have to refer to the entire module name when importing.

It's not clear what you're trying to achieve. If you only want to import the particular object attribute1, just do from package.subpackage.module import attribute1 and be done with it. You need never worry about the long package.subpackage.module once you've imported the name you want from it.

If you do want to have access to the module to access other names later, then you can do from package.subpackage import module and, as you've seen you can then do module.attribute1 and so on as much as you like.

If you want both --- that is, if you want attribute1 directly accessible and you want module accessible, just do both of the above:

from package.subpackage import module
from package.subpackage.module import attribute1
attribute1 # works
module.someOtherAttribute # also works

If you don't like typing package.subpackage even twice, you can just manually create a local reference to attribute1:

from package.subpackage import module
attribute1 = module.attribute1
attribute1 # works
module.someOtherAttribute #also works