CODEWITHSUNDEEP
python
Wilfred Hughes
Wilfred Hughes

Reputation: 31171

Why does importing symbols from a module also define the module symbol?

Given a trivial Python package with an __init__.py:

$ ls -R foo/
foo/:
__init__.py  bar.py

$ cat foo/bar.py
def do_stuff(): pass

$ cat foo/__init__.py
from .bar import *

I'm surprised that foo.bar is defined:

>>> import foo
>>> foo.bar
<module 'foo.bar' from 'foo/bar.pyc'>

My understanding of from x import * is that it doesn't define x in the current scope. For example:

>>> from abc import *
>>> abc
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'abc' is not defined

Why is foo.bar defined in my first example, even though I don't have import bar inside __init__.py?

Upvotes: 4

Views: 197

Answers (1)

hspandher
hspandher

Reputation: 16753

When you reference it by foo.bar, it is not referencing to bar used in the import statement in __init__.py file, instead it is a reference to bar module/file itself. Even if you remove all the code in __init__.py file, import foo; foo.bar would still work.

If that weren't the case, you wouldn't have been able to do something like this

import foo.bar

Since foo is a package, as it contains __init__ file, hence it's internal files can be referenced directly.

Upvotes: 1

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