Files
react/packages/react/src/ReactCurrentOwner.js
T
Andrew Clark 376d5c1b5a Split cross-package types from implementation
Some of our internal reconciler types have leaked into other packages.
Usually, these types are treated as opaque; we don't read and write
to its fields. This is good.

However, the type is often passed back to a reconciler method. For
example, React DOM creates a FiberRoot with `createContainer`, then
passes that root to `updateContainer`. It doesn't do anything with the
root except pass it through, but because `updateContainer` expects a
full FiberRoot, React DOM is still coupled to all its fields.

I don't know if there's an idiomatic way to handle this in Flow. Opaque
types are simlar, but those only work within a single file. AFAIK,
there's no way to use a package as the boundary for opaqueness.

The immediate problem this presents is that the reconciler refactor will
involve changes to our internal data structures. I don't want to have to
fork every single package that happens to pass through a Fiber or
FiberRoot, or access any one of its fields. So my current plan is to
share the same Flow type across both forks. The shared type will be a
superset of each implementation's type, e.g. Fiber will have both an
`expirationTime` field and a `lanes` field. The implementations will
diverge, but not the types.

To do this, I lifted the type definitions into a separate module.
2020-04-08 23:49:23 -07:00

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JavaScript

/**
* Copyright (c) Facebook, Inc. and its affiliates.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*
* @flow
*/
import type {Fiber} from 'react-reconciler/src/ReactInternalTypes';
/**
* Keeps track of the current owner.
*
* The current owner is the component who should own any components that are
* currently being constructed.
*/
const ReactCurrentOwner = {
/**
* @internal
* @type {ReactComponent}
*/
current: (null: null | Fiber),
};
export default ReactCurrentOwner;