`AudioFrame` deep copy

[microbit-carlos]

I think the last time we discussed this, we covered two options:

a) Copy Constructor: original = AudioFrame(); copy = AudioFrame(original)
b) Method: original = AudioFrame(); copy = original.clone()

Option a) is more Pythonic, while option b) might have been already used in the micro:bit API.

I had an action to look at the existing micro:bit API to see if a) and b) has been used before and which one might be more "microbitish".

• We currently have two instances of a copy() method with SoundEffect.copy() and Image.copy()
• We don't have any instance of a copy constructor

Apart from that, we already have keyword arguments in AudioFrame(duration, rate) that we can used as positional arguments in the initialiser, and adding a copy constructor might make the readthedocs signature a bit harder to document (we've had multiple questions about characters like * and / in the function signatures). This one is a minor thing, as we can also explain stuff more in the description, but still worth pointing out.

All in all, I think we should go with the AudioFrame.clone() option, but calling it AudioFrame.copy().

[microbit-carlos]

From @dpgeorge in #163 (comment):

I was also wondering if we should also make it a static function to be able to do new = AudioFrame.copyfrom(old). Otherwise we now we have to figure out a way to match the length of the old instance somehow when creating the new, as we cannot even do something like new = AudioFrame(size=len(old)); new.copyfrom(old).

How about allowing passing an AudioFrame to the AudioFrame constructor? This is how list, dict etc work in Python. (Did we already discuss point?)

[microbit-carlos]

Yes, using a copy constructor is more Pythonic, but taking in consideration we have two instances already of a copy() method I'm more inclined to use that. What do you think?

[microbit-carlos]

Discussed on our call and agreed to implement the copy() method.

[microbit-carlos]

Based on the changes from #205 (comment), we should add the copy() method to AudioRecording.