[zpao]

No we've known and said it for a long time but not very loudly. People haven't used them sparingly and they tend to infect a codebase. Now we're just making a more concerted effort to communicate more broadly that they can be bad.

[hardwaresofton]

Thanks for replying -- I assume in whatever planning/architecture meetings went on before react was released that this was a measured decision you all chose to take, weighing the potential dangers less dangerous than the initial usefulness. Is this assumption correct?

If you could do it again, would you leave in mixins or would you keep them out?

[zpao]

It was the right decision at the time - it made React much more familiar for people at FB who were writing PHP/Hack (Dan called this familiarity out in the post). It also enabled some great things that are still awkward with other patterns - https://github.com/reactjs/react-timer-mixin/issues/4 is an interesting case. That functionality is nice and elegant with mixins but not so with classes.

I think if we had to do it again (and get to keep the knowledge of the last few years), we'd probably skip mixins. We'd surely do some other things differently too though :)