Reimplement React.Children

[koba04]

@aweary
This is a fix for #9325 (comment)

[gaearon]

What do you think about completely rewriting React.Children implementation? It seems like traverseAllChildren is very generic and might be suboptimal by itself for React.Children implementation. Do you think you could re-implement React.Children with less abstraction overhead (it’s fine to copy and paste common parts). We could then look if the abstraction is worth it.

Would you be interested?

[gaearon]

See my comment—maybe we can both avoid allocation and make the code less abstract.

[aweary]

@koba04 happy to work with you on that ^ if you'd like!

[koba04]

@gaearon @aweary That makes sense! I'll work on that!

[koba04]

@aweary @gaearon

Could we remove ReactChildren.mapIntoWithKeyPrefixInternal?

• https://github.com/facebook/react/blob/master/src/isomorphic/children/ReactChildren.js#L204

It's not used in other React sources. I'm not sure whether it's being used in outside React, but it is an undocumented API.

• https://facebook.github.io/react/docs/react-api.html#react.children

[aweary]

I don't see it being used in react-native or react-art. This comment implies it's used by an addon, but I'm not sure which one. Maybe @trueadm can clarify.

[gaearon]

We have an internal dependency on it at FB but we'll fix it in another way. So feel free to skip it.

[gaearon]

We don't want to implement forEach in terms of map because we don't want to allocate the result just to ignore it. It's fine to duplicate the code in this case.

[koba04]

Thanks! I've fixed it!

[koba04]

duplicate of #10227

[gaearon]

Hey, sorry I didn't provide more feedback on this. As you see from my implementation I still wanted to keep the pooling. Thanks for working on it though, it helped me gather my thoughts and figure out how to go about this.

[koba04]

No problem! 😄
I've enjoyed this implementation and learned a lot from this!