autoinit.py

# only works for kwargs
class autoinit(type):
    def __call__(self, *args, **kwargs):
        rv =  super().__call__(*args, **kwargs)
        for k,v in rv.__init__.__annotations__.items():
            setattr(rv, k, eval(v, kwargs))
        return rv

class Foo(metaclass=autoinit):
    def __init__(self, x: 'x + y', y: 'y * 10', z):
        print('Foo.__init__', x, y, z)

if __name__ == '__main__':
    foo = Foo(x = 10, y = 20, z = 30)
    print(foo.x, foo.y)