Right, I just used `props.bar` in that example, you're right - it would be a bad idea to do so unless it was some kind of initializing prop (common with state-based stuff).

> The interface is the same.

Huh? foo(event) is different from foo(bar, event) and if your function is only ever going to be called with the former (ie - any dom event handler) and you want the latter... it's absolutely useful.