Sometimes-readonly property

I have a class, CameraInterface, with two properties:

• recording (a boolean)


• recording_quality (an enumeration with three possible values)

The user can push hardware buttons (this is a Raspberry Pi project) to select the recording_quality, but if the camera is already recording, the hardware will blink/buzz/otherwise indicate that you can’t change the recording_quality while you are recording.

I would like the CameraInterface object to enforce this requirement. I don’t want future me to be able to forget this requirement, and accidentally try setting the recording_quality without first making sure that recording is False. What is the most Pythonic way to do this?

I’m most familiar with Objective-C, where I might try making the property externally readonly, and then doing something like this:

- (void)setQuality:(Quality)quality
    successHandler:(void (^)(void))successHandler
    failureHandler:(void (^)(void))failureHandler
{
    if ( self.recording ) {
        if ( failureHandler ) {
            failureHandler();
        }
    }
    else {
        self.quality = quality; // internally writable
        if ( successHandler ) {
            successHandler();
        }
    }
}