[RFC] Make "key" default to value of "ref"

[syranide]

If we make key default to the value of ref if specified (plus some prefix to avoid conflicts perhaps), it seems to me like it would be a reconciliation win (key: null could be used to prevent this behavior, if it was ever needed).

The only practical difference it should make is if <input ref="a" /> is replaced by <input ref="b" /> it will now recreate the element instead of reusing it. To me that actually seems like another win, that's the behavior I would really want if that would happen and I can't think of a scenario where I wouldn't actually want that behavior.

I mentioned it briefly to @vjeux and it seemed reasonable to him at least. :)

[benjamn]

@sebmarkbage might have some thoughts on this

[sebmarkbage]

@benjamn wanted to add this a while back. I thought the use cases where this would help is very rare. You usually apply refs on static components that you know will be there, where as keys solve the problem of dynamic components in a runtime set.

They also have different semantic meaning. Keys only have to be unique in a fragment set but refs have to be unique within the whole owner component.

In the end I don't think it's worth overloading the two concepts. It makes it confusing to read the code and easy to mix them up.

I'm curious about your use case though. What's your scenario where you are using refs and also have a need for keys on the same components?

[syranide]

@sebmarkbage No use-case actually, I'm merely battling my way through React trying to understand it and this popped up in my mind. I can't come up with a scenario where I wouldn't want that behavior for the edge-cases, if I have two components of the same type, but with different arguments that I can toggle between, I would never want it to reuse the old one (say if there's an input somewhere in there).

So yeah, basically, in my mind, there's no scenario where I wouldn't want this behavior, but there are some edge-cases where I probably would want it (but yes, I could just use key if such a hypothetical sitatuation would ever happen).