Cam cv2

import cv2


class Cam(object):
    __flags_enabled = 0b00
    available_flags = {
        0b01: lambda frame: cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY),
        0b10: lambda frame: frame
    }

    def run_flags(self, frame):
        for flag in self.available_flags:
            if flag & self.__flags_enabled:
                frame = self.available_flags[flag](frame)
        return frame

    def __init__(self):
        self.__cap = cv2.VideoCapture(0)

    def __enter__(self, flags_enabled=0b01):
        while True:
            self.__flags_enabled = flags_enabled
            ret, frame = self.__cap.read()
            yield self.run_flags(frame)

    def __exit__(self, type, val, traceback):
        self.__cap.release()


with Cam() as cam:
    for frame in cam:
        cv2.imshow('Frame', frame)
        if cv2.waitKey(1) == ord('q'):
            cv2.destroyAllWindows()
            exit(0)