TypeVarsAttempt-#3.py

TypeVarsAttempt-#3.py

from dataclasses import dataclass
from typing import TypeVar


class A:
    def __init__(self, a1): ...

@dataclass
class BBuilder:
    foo: int

    def build(self) -> T: # "T" is not defined
        a1_i_dont_want_to_be_changeable = 123


        class B(A):
            def __init__(self, a2):
                super().__init__(a1=a1_i_dont_want_to_be_changeable)

        T = TypeVar('T', bound=B)

        return B

my_b_builder: BBuilder = BBuilder(foo=456)
BBuilt: T = my_b_builder.build() # "T" is not defined
my_b = BBuilt(a2='foo') # my_b: WhatTypeHintDoIPutHere