How do I type hint a method with the type of the enclosing class?

Question

I have the following code in python 3:

class Position:

    def __init__(self, x: int, y: int):
        self.x = x
        self.y = y

    def __add__(self,          


        

Answer 1

Specifying the type as string is fine, but always grates me a bit that we are basically circumventing the parser. So you better not misspell any one of these literal strings:

def __add__(self, other: 'Position') -> 'Position':
    return Position(self.x + other.x, self.y + other.y)

A slight variation is to use a bound typevar, at least then you have to write the string only once when declaring the typevar:

from typing import TypeVar

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

class Position:

    def __init__(self, x: int, y: int):
        self.x = x
        self.y = y

    def __add__(self, other: T) -> T:
        return Position(self.x + other.x, self.y + other.y)