Can a Yoga Node have multiple owners?

[kennethpu]

Report

• I have searched existing issues and this is not a duplicate

Within YGNodeInsertChild() we assert that the child we are adding cannot already have an owner. At the same time, within YGNodeRemoveChild() we have a comment indicating that "Children may be shared between parents". These two statements seem contradictory to me - is there a logical error here or am I interpreting the assert/comments incorrectly? Under what circumstances could we expect a node to wind up with multiple owners/parents?

[nicoburns]

Under what circumstances could we expect a node to wind up with multiple owners/parents?

My understanding is that multiple owners are (or were?) being used within React Native for copy-on-write trees that share subtrees. Thus, a node should only have a single owner within the same tree (descending from a particular root node), but it may be in multiple trees. Unless you really need this functionality I would recommend enforcing that nodes only have a single owner in your own use of Yoga.

[NickGerleman]

Yes, the public API does not allow multiple owners. RN Fabric uses concrete (private) Yoga node implementation, and ends up bypassing this check. I suspect some of these changes might have been made without as much awareness of the layering here.

I do want to find a way to get RN Fabric onto public Yoga API. There is a world where we make a revised Yoga API, to try to allow more client flexibility (in some other ways as well). Or possibly a world where we relax more of the public API constraints to make it possible, but it's not entirely clean.

[kennethpu]

Got it, thanks for the clarification!