Support __getattr__

[JukkaL]

Support overloading attribute access by defining a __getattr__ method. If a class has a __getattr__ method, mypy should let programs access any attributes, and the type would be the return type of __getattr__. Example:

class A:
    def __getattr__(self, name: str) -> int: return 2
a = A()
print(a.foobar)   # okay, type is int

[tommyjcarpenter]

I hit a similar issue today; I have found I need to change my code from:

table: str = getattr(someobj, "someprop", "some_constant")

to

table: str = getattr(someobj, "someprop") or "some_constant"