Python错误：AttributeError：'module'对象没有属性

Question

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

Answer 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.

Answer 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() .

Answer 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.

Answer 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.