garciat / gean Goto Github PK

From this code:

from typing import Generic, TypeVar

_T = TypeVar('_T', covariant=True)

class A: pass
class B(A): pass

class G(Generic[_T]): pass

class P(G[B]): pass

These subtype relationships arise:

B <: A
P <: G[B]
P <: G[A]

Issue: it should be possible to resolve a G[A] from a dependency P.

Likewise for contravariance.

https://docs.python.org/3/library/typing.html

• NewType
• Callable
• Generics
  • Covariance
  • Contravariance
  • Bounds
  • TypeVar restrictions (TypeVar('A', str, bytes))
• Any
• Structural subtyping
• Protocols
• Union types
• Variadic tuples
• Literals
• Forward references

Test case:

def test_forward_reference() -> None:
  class A: pass
  class B:
    a: 'A'

  container = Container()
  container.register_class(A)
  container.register_class(B)
  container.resolve(B)

Currently results in NameError: name 'A' is not defined