Python error: AttributeError: 'module' obj

问题:

I'm totally new to Python and I know this question was asked many times, but unfortunately it seems that my situation is a bit different... I have created a package (or so I think). The catalog tree is like this:

mydir
    lib   (__init__.py)
    mod1  (__init__.py, mod11.py)

In parenthesis there are files in the catalog. Both __init__.py files are zero length.

The file mydir/lib/mod1/mod11.py contains the following:

def mod12():
    print "mod12"

Now, I run python, then import lib, which works OK, then lib.mod11() or lib.mod12().

Either of the last two gives me the subject error message. Actually dir(lib) after Step 2 does not display mod11 or mod12 either. It seems I'm missing something really simple.

(I'm using Python 2.6 in Ubuntu 10.10)

Thank you

回答1:

When you import lib, you're importing the package. The only file to get evaluated and run in this case is the 0 byte __init__.py in the lib directory.

If you want access to your function, you can do something like this from lib.mod1 import mod1 and then run the mod12 function like so mod1.mod12().

If you want to be able to access mod1 when you import lib, you need to put an import mod1 inside the __init__.py file inside the lib directory.

回答2:

More accurately, your mod1 and lib directories are not modules, they are packages. The file mod11.py is a module.

Python does not automatically import subpackages or modules. You have to explicitly do it, or "cheat" by adding import statements in the initializers.

>>> import lib
>>> dir(lib)
['__builtins__', '__doc__', '__file__', '__name__', '__package__', '__path__']
>>> import lib.pkg1
>>> import lib.pkg1.mod11
>>> lib.pkg1.mod11.mod12()
mod12

An alternative is to use the from syntax to "pull" a module from a package into you scripts namespace.

>>> from lib.pkg1 import mod11

Then reference the function as simply mod11.mod12().

回答3:

The way I would do it is to leave the __ init__.py files empty, and do:

import lib.mod1.mod11
lib.mod1.mod11.mod12()

or

from lib.mod1.mod11 import mod12
mod12()

You may find that the mod1 dir is unnecessary, just have mod12.py in lib.

回答4:

My solution is put those imports in __init__.py of lib:

in file: __init__.py
import mod1

Then,

import lib
lib.mod1

would work fine.