Python submodule imports using __init__.py

Question

I\'m learning Python, and I can\'t figure out how imports in __init__.py work.

I understand from the Python tutorial that the __init__.py f

Answer 1

First, you have to understand how import alone work:

import test.submodule.do_something

Would try to load do_something from submodule itself loaded from test.

You want to load something from subpackage, so start with that:

import subpackage

Fine, subpackage/__init__.py is loaded.

Now, you want the do_something() function which is in the file (a "module") hello_world.py. Easy:

from subpackage.hello_world import do_something

And you are done! Just read this line loud, it does exactly what it says: import do_something from the module hello_world which is in the subpackage package.

Try that in test.py

from subpackage.hello_world import do_something

do_something()

It should work just fine.

Now, the second issue:

__init__.py won't be called in package/ since you don't use package/ as a package. __init__.py will be used if you do an import of package/ or anything in it, for eg:

from package import test

Otherwise, it won't be loaded at all.

However, if you want to load do_something() on the import of subpackage, put from submodule.hello_word import do_something in subpackage/__init__.py, and then, in you test.py, do a import subpackage.