为什么从同级包中导入模块被视为反模式？

Question

I just started learning how to code in Python (came from a Java background).

I have this very basic project structure, using the simplest form of MVC I can muster:

myproject
    controllers
        __init__.py
        controller.py
    models
        __init__.py
        model.py
    views
        __init__.py
        view.py
    main.py

Provided that I start with view.py and I need to make a link between this and its controller, I know that I have to import the controller by using the import commands:

from controllers import controller

I know for a fact that this doesn't work, so I use relative paths in order to try and make it work.

from ..controllers import controller

I also know that this doesn't work as it can't really see the folder, in order to fix that I need to make the myproject folder a package in and of itself. But this doesn't make sense to me.

I read somwehere that this kind of file structure is an "anti-pattern" almost. But why though? MVC is structurally sound by decoupling their functions, so separating them into their own packages makes sense.

Answer 1

You must not think in terms of "files", but in terms of packages . Your entire project should be its own package which is installed in your Python environment like any other package. There's no fundamental difference between these:

from django.db import models

from myproject.controllers import controller

django is a globally installed package. myproject should be a globally installed package.

If wouldn't make sense to have a global " controllers " module floating around, it should clearly be part of a larger package.

Within a package you can do relative imports if you want to, which is mostly shorthand and perhaps helps a bit if you rename the top level package, but is otherwise inconsequential.

Always think in terms of eventually publishing your package to PyPI or building a wheel which you distribute to production servers for installation, even if you're never going to do either of those things.