I’m writing a Python package in which there are a lot of units (classes, functions…) that are referencing each other. I face problems with circular imports.

How to solve something like that:

a.py:

from .b import B
from .c import C

@dataclass
class A:
    b: B = field(default_factory=B)
    c: C = field(default_factory=C)

b.py:

from .a import A
from .c import C

@dataclass
class B:
    a: A = field(default_factory=A)
    c: C = field(default_factory=C)

c.py:

from .a import A
from .b import B

@dataclass
class C:
    a: A = field(default_factory=A)
    b: B = field(default_factory=B)

The above code will lead to circular imports. I know I can solve them by putting all classes into one file. But there is a lot of code, and if I put all classes into one file each time I have this problem, then I have would very big files, and I prefer to split it into many files, for better programming experience. What would be the best way to solve that?

What I tried:

1. I tried putting names of the classes in ' (apostrophes). But that doesn’t work for deafult_factory.

2. I tried using import instead, but I can’t figure out how to do relative imports with import keyword. Something like that: import .a didn’t work.