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Removed an unnecessary wrapper object from state (#12383) 

* Removed an unnecessary wrapper object from state
* Moved unsubscribe from state to class field and tweaked comments
This commit is contained in:
Brian Vaughn 2018-03-15 11:43:01 -07:00 committed by GitHub
parent d38616d693
commit 2738e84805
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1 changed files with 9 additions and 18 deletions
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27
packages/create-subscription/src/createSubscription.js
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@ -51,9 +51,6 @@ export function createSubscription<Property, Value>(
};
type State = {
source: Property,
unsubscribeContainer: {
unsubscribe: Unsubscribe | null,
},
value: Value | void,
};
@ -61,22 +58,18 @@ export function createSubscription<Property, Value>(
class Subscription extends React.Component<Props, State> {
state: State = {
source: this.props.source,
unsubscribeContainer: {
unsubscribe: null,
},
value:
this.props.source != null
? getCurrentValue(this.props.source)
: undefined,
};
_unsubscribe: Unsubscribe | null = null;
static getDerivedStateFromProps(nextProps, prevState) {
if (nextProps.source !== prevState.source) {
return {
source: nextProps.source,
unsubscribeContainer: {
unsubscribe: null,
},
value:
nextProps.source != null
? getCurrentValue(nextProps.source)
@ -125,18 +118,16 @@ export function createSubscription<Property, Value>(
});
};
// Store subscription for later (in case it's needed to unsubscribe).
// This is safe to do via mutation since:
// 1) It does not impact render.
// 2) This method will only be called during the "commit" phase.
// Store the unsubscribe method for later (in case the subscribable prop changes).
const unsubscribe = subscribe(source, callback);
invariant(
typeof unsubscribe === 'function',
'A subscription must return an unsubscribe function.',
);
this.state.unsubscribeContainer.unsubscribe = unsubscribe;
// It's safe to store unsubscribe on the instance because
// We only read or write that property during the "commit" phase.
this._unsubscribe = unsubscribe;
// External values could change between render and mount,
// In some cases it may be important to handle this case.
@ -148,10 +139,10 @@ export function createSubscription<Property, Value>(
}
unsubscribe(state: State) {
const {unsubscribe} = state.unsubscribeContainer;
if (typeof unsubscribe === 'function') {
unsubscribe();
if (typeof this._unsubscribe === 'function') {
this._unsubscribe();
}
this._unsubscribe = null;
}
}