mypy complains with aenum.Enum, but not enum.Enum

[BrendanSimon]

Using Python 3.7 on Debian Buster 10.9 development host (target system is actually python2.7 based system).

The following code snippet gives a mypy error when I use aenum.Enum.

Argument "reg_id" to "register_get" has incompatible type "int"; expected "Register_Address"

No mypy error is reported when useing enum.Enum.

# from enum import Enum
from aenum import Enum

class Register_Address( Enum ):
    STATUS       = 0x0000
    GPIO_CTRL    = 0x0004

def register_get(
        reg_id,                 # type: Register_Address
    ) :                         # type: (...) -> int
    """Get a 32-bit register value."""
    # value = my_ioctl( reg_id, ... )
    value = reg_id.value
    return value

value = register_get( reg_id=Register_Address.GPIO_CTRL )

[domdfcoding]

mypy ships with a plugin [1] for the stdlib enum module, but it doesn't understand aenum. You could either extend that plugin to support aenum, or use it as the basis for a standalone plugin.

[1] https://github.com/python/mypy/blob/master/mypy/plugins/enums.py

[BrendanSimon]

Yes, aenum with proper type checking would be awesome, or a separate package such as types-aenum :)

I have worked around it another way by using Python3 enum for type checking and aenum for real code. It's not as good has having the real code type checked, but at least the "noise" has gone.

from typing import TYPE_CHECKING

if TYPE_CHECKING :
    #! this is only processed by MyPy (i.e. not at runtime)
    from enum import Enum
else :
    #! this is real runtime code
    from aenum import Enum

[konstantinmiller]

Another "ugly" workaround that mypy understands is to use reg_id=Register_Address(Register_Address.GPIO_CTRL)