import a.b also imports a?

Question

When I import a subpackage in a package, can I rely on the fact that the parent package is also imported ?

e.g. this works

python -c \"import os.path; pr         


        

Answer 1

This is a good question. If you look at the source code for os.py you find this line:

sys.modules['os.path'] = path

So there's our module. But what's path? Well that depends on your OS. For Windows, it's defined in this block:

elif 'nt' in _names:
    name = 'nt'
    linesep = '\r\n'
    from nt import *
    try:
        from nt import _exit
    except ImportError:
        pass
    import ntpath as path

    import nt
    __all__.extend(_get_exports_list(nt))
    del nt

Basically, os.path is special in this context.

Short version: Python does some stuff behind the scenes to make os.path. You probably shouldn't rely on it to get other modules. "Explicit is better than implicit" is how the zen goes.