Importing the classes from a python module directly

July 28, 2023

I have a python module I am writing that has the structure:

top_level_module/
    __init__.py
    sub_module1/
        __init__.py
        Class1.py
        Class2.py
    sub_module2/
        __init__.py
        Class3.py

The capitalizations there are correct. This structure was chosen by someone else but they are set on keeping it like that (I believe they are used to C++ or Java naming). I want to be able to import the classes easier than a bunch of consecutive
from top_level_module.sub_module1.Class1 import Class1 statements. Is there a way to do this that is reasonable?

I currently have a classes.py in a couple modules that just import all the classes so I can at least do:
from top_level_module.sub_module1.classes import Class1, Class2
but it just seems wrong. I would rather use init.py somehow, but I do not want to block the ability to import the modules names ClassX and only allow the import of the classes within them.

I understand that the question is similar to How to import class from a Python package directly but I think it is different enough.

>Solution :

in the top_level_module/sub_module1/__init__.py file, you can import the classes from Class1.py and Class2.py

from .Class1 import Class1
from .Class2 import Class2

and of course in the top_level_module/sub_module2/__init__.py file, you can do the same for Class3.py

from .Class3 import Class3

now, you can import the classes directly from the sub-modules without having to explicitly specify the file names and the __init__.py files act as a bridge between the top-level module and the classes within the sub-modulesand, something like this :

from top_level_module.sub_module1 import Class1, Class2
from top_level_module.sub_module2 import Class3

update:
when you import a package,python looks for an __init__.py file in the directory and if it finds one,it executes the code inside the __init__.py file, so it allows you to define what gets imported when you import the package!

in your example,if you want to import sub_module1 as a package and also import the classes within it,you can modify the __init__.py file in top_level_module/sub_module1

from .Class1 import Class1
from .Class2 import Class2

__all__ = ['Class1', 'Class2']

as you see __all__ variable is a list that specifies the names that should be imported when you use the from sub_module1 import * syntax and by default,python only imports names that do not start with an underscore,so by setting __all__ to include the class names,you can now import the classes directly from sub_module1 or import the package itself!!!

let me give you an example :

from top_level_module.sub_module1 import Class1, Class2
from top_level_module.sub_module1 import sub_module1

#imported classes
obj1 = Class1()
obj2 = Class2()

#imported package
obj3 = sub_module1.Class1()
obj4 = sub_module1.Class2()

good luck !