无法解决“导入为”的情况（“AttributeError模块x没有属性y”）

Question

I have a project with the following structure:

project/
    driver.py
    lib/
        __init__.py
        core/
            util.py
            common.py
            __init__.py

---

# project/driver.py

import lib.core.common as abc
pass

---

# project/lib/core/__init__.py

from .util import Worker

---

# project/lib/core/util.py

import lib.core.common as abc

class Worker:
    pass

---

# project/lib/core/common.py

def stuff():
    pass

Now when I run python3 driver.py (from project's directory), I get the following error:

Traceback (most recent call last):
  File "driver.py", line 1, in <module>
    import lib.core.common as abc
  File "/home/user/project/lib/core/__init__.py", line 1, in <module>
    from .util import Worker
  File "/home/user/project/lib/core/util.py", line 1, in <module>
    import lib.core.common as abc
AttributeError: module 'lib' has no attribute 'core'

This happens only when both conditions are met:

1. When I do import lib.core.common as abc instead of import lib.core.common .
2. When the project/lib/core/__init__.py contains from .util import Worker import.

The thing is that I would like to keep the import lib.core.common as abc import form.

Could anybody explain what's going on here, please?

Answer 1

You have circular dependent imports. you try to execute

import lib.core.common as abc

in two files, in driver.py and in util.py

The easiest way to fix this is to move the path import to the end of the node module, some docs , or

def dostuff():
    from foo import bar
    ...

or this also will work,

from lib.core import common as abc

When Python imports a module, it checks the module registry to see if the module was already imported. If the module was already registered, Python uses that existing object from cache. The module registry is a table of modules that have been initialized and indexed by module name. This table can be accessed through sys.modules .

If it was not registered, Python finds the module, initializes it if necessary, and executes it in the new module's namespace.