Prefix _context property on returned ReactContext from createContext …

[Andarist]

Context 🤣:
https://twitter.com/AndaristRake/status/979835281871441920

Provider/Consumer are circular (with a comment about it, so I guess it's by design) which makes this possible:

const ctx = React.createContext()
ctx.Consumer.Consumer.Consumer.Consumer.Provider

which is funny, but I don't know if anything can be done about it.

cc @acdlite

[jaydenseric]

This was a breaking change for packages such as react-apollo and graphql-react: https://github.com/jaydenseric/graphql-react/blob/v1.0.0-alpha.4/src/preload.mjs#L114.

[gaearon]

This field was never documented or mentioned in public communication. I understand the frustration but it was never intended to be a public API and we might need to change how it works in either case in the future.

Similarly currentValue is an internal property and assigning to it was never supported. I encourage library authors to double check with us if they're using something that isn't documented.

[gaearon]

(Which is the reason why prefixing it now, a few days after the release, is better in the long term than if we just broke it when implementation changes in the future.)

[jaydenseric]

Is there a better, or "official" way to traverse a tree with context for SSR purposes? A prefix won't discourage usage if there is no alternative.

[gaearon]

Could you file a new issue please and describe the use case (preferably with some code examples)?

[sebmarkbage]

The official way to that general problem space is “suspense”.

I doubt that we’ll be able to add an official traversal api since we’re trying to compile away indirection so exposing the raw tree would defeat any compiler optimizations.

[sebmarkbage]

I suppose this is more like a custom renderer. If so, maybe it doesn’t need to share state with React?

[sebmarkbage]

react-is can help you brand check things properly.

Updating the current context value is sketchy though. I’d need to understand why but ideally you could just use new WeakMap().set(Context, value) and read from that.