How Do I Correctly Call A Function That Takes A "custom Enum" As Argument Using Ctypes And Ctypes Based Enums?

I really hope some Python/Ctypes/C expert can help me with this one, it is probably my lack of knowledge on the typing structure to correctly use Ctypes when using Python to intera

Solution 1:

Assuming this implementation, test.cpp:

#include <stdint.h>

enum led_property : uint8_t {
    LED_OFF = 0,
    LED_POWER
};

extern "C" __declspec(dllexport) int32_t configure_led(enum led_property prop, int32_t value) {
    return prop * value;
}

This will allow only LED values for the first parameter:

from ctypes import *
from enum import Enum,auto

class LED(Enum):

    OFF = 0
    POWER = auto()  # autoincrement from last value

    @classmethod
    def from_param(cls,obj):
        if not isinstance(obj,LED):
            raise TypeError('not an LED enumeration')
        return c_int8(obj.value)

dll = CDLL('./test')
dll.configure_led.argtypes = LED,c_int32
dll.configure_led.restype = c_int32

print(dll.configure_led(LED.OFF,5))   # prints 0
print(dll.configure_led(LED.POWER,5)) # prints 5
print(dll.configure_led(0,5))         # not an LED enumeration