Update specification for directives for sys.implementation and sys.platform checks. by Josverl · Pull Request #2173 · python/typing

Josverl

If possible this would really help with creating readable and maintainable type stubs for MicroPython.
even with the proposed sys.implementation.name check we still see significant API differences due the underlying MCU vendor SDKs being significantly different.
Though MicroPython tries to abstract much of these differences away that is not entirly possible as the underlying SDK or hardware is simply different. This is a common source of errors when code is ported from one MCU architecture to another.
For instance Timers are available on all platforms, but with many different default values.

While the below would work

# machine.pyi 
class Timer():
    """"Timer object"""

    if sys.implementation.name == "micropython" and (sys.platform == "esp32" or sys.platform ==  "mimxrt" or  sys.platform ==  "rp2" or sys.platform ==  "samd" or sys.platform ==  "stm32" or sys.platform ==  "alif" or sys.platform ==  "webassembly"): 
        @overload
        def __init__(
            self,
            id: int,
            /,
            *,
            mode: int = PERIODIC,
            period: int | None = None,
            callback: Callable[[Timer], None] | None = None,
            hard: bool | None = None,
        ):...
    elif sys.implementation.name == "micropython" and (sys.platform == "esp8266" or sys.platform ==  "unix" or  sys.platform ==  "windows"  or sys.platform ==  "zephyr"): 
        @overload
        def __init__(
            self,
            id: int = -1,
            /,
            *,
            mode: int = PERIODIC,
            period: int | None = None,
            callback: Callable[[Timer], None] | None = None,
        ):...

the below is much simpler to understand and maintain.

class Timer():
    """"Timer object"""

    if sys.implementation.name == "micropython" and (sys.platform in ("esp32", "mimxrt", "rp2", "samd", "stm32", "alif", "webassembly")): 
        @overload
        def __init__(
            self,
            id: int,
            /,
            *,
            mode: int = PERIODIC,
            period: int | None = None,
            callback: Callable[[Timer], None] | None = None,
            hard: bool | None = None,
        ):...
    elif sys.implementation.name == "micropython" and (sys.platform in ("esp8266", "unix", "windows", "zephyr")): 
        @overload
        def __init__(
            self,
            id: int = -1,
            /,
            *,
            mode: int = PERIODIC,
            period: int | None = None,
            callback: Callable[[Timer], None] | None = None,
        ):...

I think it would be reasonable to explicitly restrict this to "a tuple of literal strings",assuming that simplies the implementation.
Negative membership option could also be omitted , I think that would still be sufficient.