python modules hierarchy naming convention

问题

I'd like to have modules/packages structure like following:

/__init__.py
/mymodule.py
/mymodule/
/mymodule/__init__.py
/mymodule/submodule.py

And then use modules like:

import mymodule
import mymodule.submodule

But it seems like file "mymodule.py" conflicts with "mymodule" directory.

What's the correct naming convention here?

回答1:

If you want to make a package, you have to understand how Python translates filenames to module names.

The file mymodule.py will be available as the mymodule, assuming the interpreter finds it in a directory in the Python search path. If you're on a case-insensitive filesystem, it might also be importable with different capitalization (but you should avoid using such system-dependent behavior).

A package is a directory with an __init__.py file in it. There's been some movement recently to allow packages without those files, but I'm going to ignore that less-common case for this answer. A package becomes a module inside Python, with its code coming from the __init__.py file. So the file mypackage/__init__.py can be imported as mypackage.

There's no meaning to an __init__.py file directly in the Python search path (well, I suppose you could import it an an __init__ module, but this is probably a bad idea).

So, for your situation, here's the appropriate filesystem layout:

toplevel/
    mymodule/
        __init__.py     # put code here for mymodule
        submodule.py    # put code here for mymodule.submodule

Only the toplevel folder should be in the Python search path.

回答2:

You are dealing with a package. The package structure you should have is:

/some-parent-directory # This needs to be on sys.path
    /mymodule  # This is not really a module - it's a package
        __init__.py  # import mymodule
        # init is loaded when you `import mymodule` or anything below it
        some.py  # import mymodule.some
        implementation.py  # import mymodule.implementation
        files.py  # import mymodule.files
        /submodule
            __init__.py  # import mymodule.submodule
            # init is loaded when you `import mymodule.submodule` or anything below it
            submodule_impl.py  # import mymodule.submodule.submodule_impl
            goes.py  # import mymodule.submodule.goes
            here.py  # import mymodule.submodule.here

As long as the parent directory is on sys.path you will be able to call import mymodule or from mymodule.submodule import something without issue.

If you want something to be available from the root level of a package (i. e. from mymodule import SomeItem or from a sub-package from mymodule.submodule import AnotherItem) then you can import it into the appropriate __init__.py file.

So, for example, let's say you wanted the class CustomClass defined in the submodule_impl.py module to be importable directly from submodule. Your submodule/__init__.py would have to contain the following:

from .submodule_impl import CustomClass

Then you would be able to import CustomClass directly from submodule (i. e. from mymodule.submodule import CustomClass)

来源：https://stackoverflow.com/questions/15237806/python-modules-hierarchy-naming-convention

标签

python

module

python-module