Python type hinting without cyclic imports

Question

I\'m trying to split my huge class into two; well, basically into the \"main\" class and a mixin with additional functions, like so:

main.py file:

Answer 1

For people struggling with cyclic imports when importing class only for Type checking: you will likely want to use a Forward Reference (PEP 484 - Type Hints):

When a type hint contains names that have not been defined yet, that definition may be expressed as a string literal, to be resolved later.

So instead of:

class Tree:
    def __init__(self, left: Tree, right: Tree):
        self.left = left
        self.right = right

you do:

class Tree:
    def __init__(self, left: 'Tree', right: 'Tree'):
        self.left = left
        self.right = right