[BEAM-10690] Python type hints: support constrained TypeVars

• Type: Bug
• Status: Open
• Priority: P3
• Resolution: Unresolved
• Component/s: sdk-py-core
• Labels: types
• Assignee: Unassigned
• Reporter: Udi Meiri
• Created: 12/Aug/20 17:54
• Updated: 04/Jun/22 17:13

Description

Support the following syntax when converting to internal Beam types,
and raise a TypeCheckError when trying to bind anything that isn't Any, one of the listed types, or a subtype of the listed types.

AnyStr = TypeVar('AnyStr', Text, bytes)

See: https://www.python.org/dev/peps/pep-0484/#generics (lots of cases to check)