How Python imports an instance of a class

March 15, 2024

I’m trying to find out how exactly importing works in Python.
Let’s say I have a foo.py module that contains the following class:

class Foo: 
    def __init__(self, *args, **kwargs): 
        ... 


foo = Foo()

Now, I want to import it in other modules.

Is it going to use the same instance every time that I import it or will make different instances whenever I import it and is it even a good way to instantiate a class or it’d be better to import the Foo class and create an instance in modules that imported it(As it’s obvious, this class doesn’t need any args and kwargs).

>Solution :

Import it in the usual way:
from foo import Foo

If this is the first time, the foo.py code will execute and the “class” / “def” statements will generate bytecode for the interpreter.
And we make a note of it in sys.modules.

Subsequent imports will benefit from a cache hit, so we won’t repeat all that evaluation work.

Bottom line: you get exactly one instance of the code in that class.