generic namedtuple

main.py

from typing import TYPE_CHECKING, TypeVar, Generic, Tuple
from typing_extensions import reveal_type

T1 = TypeVar("T1")
T2 = TypeVar("T2")

if TYPE_CHECKING:
    # This is how Group looks like to the type checker
    class Group(Tuple[T1, T2], Generic[T1, T2]):
        def __new__(cls, key: T1, group: T2) -> "Group[T1, T2]": ...
        @property
        def key(self) -> T1: ...
        @property
        def group(self) -> T2: ...

else:
    # This is the actual implementation of Group, aka literally a tuple with two boltons
    class Group(tuple):
        def __new__(cls, key, group):
            return tuple.__new__(cls, (key, group))

        @property
        def key(self):
            return self[0]

        @property
        def group(self):
            return self[1]


# Can unpack/index the Group because its literally a tuple at runtime
G1 = Group(1, "hello")
key1, grp1 = G1
key1 = G1[0]
grp1 = G1[1]
key1 = G1.key
grp1 = G1.group

# Types are ok
if TYPE_CHECKING:
    reveal_type(key1)  # Revealed type is "builtins.int"
    reveal_type(grp1)  # Revealed type is "builtins.str"
    reveal_type(G1.key)  # Revealed type is "builtins.int"
    reveal_type(G1.group)  # Revealed type is "builtins.str"
    reveal_type(G1[0])  # Revealed type is "builtins.int"
    reveal_type(G1[1])  # Revealed type is "builtins.str"

# And it *is* a generic
G2 = Group(False, 1.0)
key2, msg2 = G2
if TYPE_CHECKING:
    reveal_type(key2)  # Revealed type is "builtins.bool"
    reveal_type(msg2)  # Revealed type is "builtins.float"