Remove isEqual argument

The isEqual argument mostly meant as a strawman. It has some known flaws: chiefly, if the isEqual function must always be in sync with the selector function; if isEqual changes, then isEqual is not valid for that render, because it'd be comparing the previous type with a new type. We have a few other ideas for how to solve the underlying problem, but in the meantime, let's remove it since we know it's not what we'll end up shipping.
facebook · Feb 11, 2021 · a22f61c · a22f61c
1 parent 730d3a0
commit a22f61c
Show file tree

Hide file tree

Showing 7 changed files with 32 additions and 188 deletions.
diff --git a/packages/react-debug-tools/src/ReactDebugHooks.js b/packages/react-debug-tools/src/ReactDebugHooks.js
@@ -132,7 +132,6 @@ function useContext<T>(
 function useSelectedContext<C, S>(
   Context: ReactContext<C>,
   selector: C => S,
-  isEqual: ((S, S) => boolean) | void,
 ): S {
   const context = Context._currentValue;
   const selection = selector(context);

diff --git a/packages/react-dom/src/server/ReactPartialRendererHooks.js b/packages/react-dom/src/server/ReactPartialRendererHooks.js
@@ -254,7 +254,6 @@ function useContext<T>(
 function useSelectedContext<C, S>(
   Context: ReactContext<C>,
   selector: C => S,
-  isEqual: ((S, S) => boolean) | void,
 ): S {
   if (__DEV__) {
     currentHookNameInDev = 'useSelectedContext';

diff --git a/packages/react-reconciler/src/ReactFiberHooks.new.js b/packages/react-reconciler/src/ReactFiberHooks.new.js
@@ -638,7 +638,6 @@ function updateWorkInProgressHook(): Hook {
 function mountSelectedContext<C, S>(
   Context: ReactContext<C>,
   selector: C => S,
-  isEqual: ((S, S) => boolean) | void,
 ): S {
   if (!enableContextSelectors) {
     return (undefined: any);
@@ -654,7 +653,6 @@ function mountSelectedContext<C, S>(
 function updateSelectedContext<C, S>(
   Context: ReactContext<C>,
   selector: C => S,
-  isEqual: ((S, S) => boolean) | void,
 ): S {
   if (!enableContextSelectors) {
     return (undefined: any);
@@ -664,20 +662,7 @@ function updateSelectedContext<C, S>(
   const context = readContextInsideHook(Context);
   const newSelection = selector(context);
   const oldSelection: S = hook.memoizedState;
-  if (isEqual !== undefined) {
-    if (__DEV__) {
-      if (typeof isEqual !== 'function') {
-        console.error(
-          'The optional third argument to useSelectedContext must be a ' +
-            'function. Instead got: %s',
-          isEqual,
-        );
-      }
-    }
-    if (isEqual(newSelection, oldSelection)) {
-      return oldSelection;
-    }
-  } else if (is(newSelection, oldSelection)) {
+  if (is(newSelection, oldSelection)) {
     return oldSelection;
   }
   markWorkInProgressReceivedUpdate();
@@ -2267,17 +2252,13 @@ if (__DEV__) {
       mountHookTypesDev();
       return readContext(context, observedBits);
     },
-    useSelectedContext<C, S>(
-      context: ReactContext<C>,
-      selector: C => S,
-      isEqual: ((S, S) => boolean) | void,
-    ): S {
+    useSelectedContext<C, S>(context: ReactContext<C>, selector: C => S): S {
       currentHookNameInDev = 'useSelectedContext';
       mountHookTypesDev();
       const prevDispatcher = ReactCurrentDispatcher.current;
       ReactCurrentDispatcher.current = InvalidNestedHooksDispatcherOnMountInDEV;
       try {
-        return mountSelectedContext(context, selector, isEqual);
+        return mountSelectedContext(context, selector);
       } finally {
         ReactCurrentDispatcher.current = prevDispatcher;
       }
@@ -2416,17 +2397,13 @@ if (__DEV__) {
       updateHookTypesDev();
       return readContext(context, observedBits);
     },
-    useSelectedContext<C, S>(
-      context: ReactContext<C>,
-      selector: C => S,
-      isEqual: ((S, S) => boolean) | void,
-    ): S {
+    useSelectedContext<C, S>(context: ReactContext<C>, selector: C => S): S {
       currentHookNameInDev = 'useSelectedContext';
       updateHookTypesDev();
       const prevDispatcher = ReactCurrentDispatcher.current;
       ReactCurrentDispatcher.current = InvalidNestedHooksDispatcherOnMountInDEV;
       try {
-        return mountSelectedContext(context, selector, isEqual);
+        return mountSelectedContext(context, selector);
       } finally {
         ReactCurrentDispatcher.current = prevDispatcher;
       }
@@ -2561,17 +2538,13 @@ if (__DEV__) {
       updateHookTypesDev();
       return readContext(context, observedBits);
     },
-    useSelectedContext<C, S>(
-      context: ReactContext<C>,
-      selector: C => S,
-      isEqual: ((S, S) => boolean) | void,
-    ): S {
+    useSelectedContext<C, S>(context: ReactContext<C>, selector: C => S): S {
       currentHookNameInDev = 'useSelectedContext';
       updateHookTypesDev();
       const prevDispatcher = ReactCurrentDispatcher.current;
       ReactCurrentDispatcher.current = InvalidNestedHooksDispatcherOnUpdateInDEV;
       try {
-        return updateSelectedContext(context, selector, isEqual);
+        return updateSelectedContext(context, selector);
       } finally {
         ReactCurrentDispatcher.current = prevDispatcher;
       }
@@ -2707,17 +2680,13 @@ if (__DEV__) {
       updateHookTypesDev();
       return readContext(context, observedBits);
     },
-    useSelectedContext<C, S>(
-      context: ReactContext<C>,
-      selector: C => S,
-      isEqual: ((S, S) => boolean) | void,
-    ): S {
+    useSelectedContext<C, S>(context: ReactContext<C>, selector: C => S): S {
       currentHookNameInDev = 'useSelectedContext';
       updateHookTypesDev();
       const prevDispatcher = ReactCurrentDispatcher.current;
       ReactCurrentDispatcher.current = InvalidNestedHooksDispatcherOnRerenderInDEV;
       try {
-        return updateSelectedContext(context, selector, isEqual);
+        return updateSelectedContext(context, selector);
       } finally {
         ReactCurrentDispatcher.current = prevDispatcher;
       }
@@ -2855,18 +2824,14 @@ if (__DEV__) {
       mountHookTypesDev();
       return readContext(context, observedBits);
     },
-    useSelectedContext<C, S>(
-      context: ReactContext<C>,
-      selector: C => S,
-      isEqual: ((S, S) => boolean) | void,
-    ): S {
+    useSelectedContext<C, S>(context: ReactContext<C>, selector: C => S): S {
       currentHookNameInDev = 'useSelectedContext';
       warnInvalidHookAccess();
       mountHookTypesDev();
       const prevDispatcher = ReactCurrentDispatcher.current;
       ReactCurrentDispatcher.current = InvalidNestedHooksDispatcherOnMountInDEV;
       try {
-        return mountSelectedContext(context, selector, isEqual);
+        return mountSelectedContext(context, selector);
       } finally {
         ReactCurrentDispatcher.current = prevDispatcher;
       }
@@ -3016,18 +2981,14 @@ if (__DEV__) {
       updateHookTypesDev();
       return readContext(context, observedBits);
     },
-    useSelectedContext<C, S>(
-      context: ReactContext<C>,
-      selector: C => S,
-      isEqual: ((S, S) => boolean) | void,
-    ): S {
+    useSelectedContext<C, S>(context: ReactContext<C>, selector: C => S): S {
       currentHookNameInDev = 'useSelectedContext';
       warnInvalidHookAccess();
       updateHookTypesDev();
       const prevDispatcher = ReactCurrentDispatcher.current;
       ReactCurrentDispatcher.current = InvalidNestedHooksDispatcherOnUpdateInDEV;
       try {
-        return updateSelectedContext(context, selector, isEqual);
+        return updateSelectedContext(context, selector);
       } finally {
         ReactCurrentDispatcher.current = prevDispatcher;
       }
@@ -3178,18 +3139,14 @@ if (__DEV__) {
       updateHookTypesDev();
       return readContext(context, observedBits);
     },
-    useSelectedContext<C, S>(
-      context: ReactContext<C>,
-      selector: C => S,
-      isEqual: ((S, S) => boolean) | void,
-    ): S {
+    useSelectedContext<C, S>(context: ReactContext<C>, selector: C => S): S {
       currentHookNameInDev = 'useSelectedContext';
       warnInvalidHookAccess();
       updateHookTypesDev();
       const prevDispatcher = ReactCurrentDispatcher.current;
       ReactCurrentDispatcher.current = InvalidNestedHooksDispatcherOnUpdateInDEV;
       try {
-        return updateSelectedContext(context, selector, isEqual);
+        return updateSelectedContext(context, selector);
       } finally {
         ReactCurrentDispatcher.current = prevDispatcher;
       }

diff --git a/packages/react-reconciler/src/ReactFiberHooks.old.js b/packages/react-reconciler/src/ReactFiberHooks.old.js
@@ -638,7 +638,6 @@ function updateWorkInProgressHook(): Hook {
 function mountSelectedContext<C, S>(
   Context: ReactContext<C>,
   selector: C => S,
-  isEqual: ((S, S) => boolean) | void,
 ): S {
   if (!enableContextSelectors) {
     return (undefined: any);
@@ -654,7 +653,6 @@ function mountSelectedContext<C, S>(
 function updateSelectedContext<C, S>(
   Context: ReactContext<C>,
   selector: C => S,
-  isEqual: ((S, S) => boolean) | void,
 ): S {
   if (!enableContextSelectors) {
     return (undefined: any);
@@ -664,20 +662,7 @@ function updateSelectedContext<C, S>(
   const context = readContextInsideHook(Context);
   const newSelection = selector(context);
   const oldSelection: S = hook.memoizedState;
-  if (isEqual !== undefined) {
-    if (__DEV__) {
-      if (typeof isEqual !== 'function') {
-        console.error(
-          'The optional third argument to useSelectedContext must be a ' +
-            'function. Instead got: %s',
-          isEqual,
-        );
-      }
-    }
-    if (isEqual(newSelection, oldSelection)) {
-      return oldSelection;
-    }
-  } else if (is(newSelection, oldSelection)) {
+  if (is(newSelection, oldSelection)) {
     return oldSelection;
   }
   markWorkInProgressReceivedUpdate();
@@ -2267,17 +2252,13 @@ if (__DEV__) {
       mountHookTypesDev();
       return readContext(context, observedBits);
     },
-    useSelectedContext<C, S>(
-      context: ReactContext<C>,
-      selector: C => S,
-      isEqual: ((S, S) => boolean) | void,
-    ): S {
+    useSelectedContext<C, S>(context: ReactContext<C>, selector: C => S): S {
       currentHookNameInDev = 'useSelectedContext';
       mountHookTypesDev();
       const prevDispatcher = ReactCurrentDispatcher.current;
       ReactCurrentDispatcher.current = InvalidNestedHooksDispatcherOnMountInDEV;
       try {
-        return mountSelectedContext(context, selector, isEqual);
+        return mountSelectedContext(context, selector);
       } finally {
         ReactCurrentDispatcher.current = prevDispatcher;
       }
@@ -2416,17 +2397,13 @@ if (__DEV__) {
       updateHookTypesDev();
       return readContext(context, observedBits);
     },
-    useSelectedContext<C, S>(
-      context: ReactContext<C>,
-      selector: C => S,
-      isEqual: ((S, S) => boolean) | void,
-    ): S {
+    useSelectedContext<C, S>(context: ReactContext<C>, selector: C => S): S {
       currentHookNameInDev = 'useSelectedContext';
       updateHookTypesDev();
       const prevDispatcher = ReactCurrentDispatcher.current;
       ReactCurrentDispatcher.current = InvalidNestedHooksDispatcherOnMountInDEV;
       try {
-        return mountSelectedContext(context, selector, isEqual);
+        return mountSelectedContext(context, selector);
       } finally {
         ReactCurrentDispatcher.current = prevDispatcher;
       }
@@ -2561,17 +2538,13 @@ if (__DEV__) {
       updateHookTypesDev();
       return readContext(context, observedBits);
     },
-    useSelectedContext<C, S>(
-      context: ReactContext<C>,
-      selector: C => S,
-      isEqual: ((S, S) => boolean) | void,
-    ): S {
+    useSelectedContext<C, S>(context: ReactContext<C>, selector: C => S): S {
       currentHookNameInDev = 'useSelectedContext';
       updateHookTypesDev();
       const prevDispatcher = ReactCurrentDispatcher.current;
       ReactCurrentDispatcher.current = InvalidNestedHooksDispatcherOnUpdateInDEV;
       try {
-        return updateSelectedContext(context, selector, isEqual);
+        return updateSelectedContext(context, selector);
       } finally {
         ReactCurrentDispatcher.current = prevDispatcher;
       }
@@ -2707,17 +2680,13 @@ if (__DEV__) {
       updateHookTypesDev();
       return readContext(context, observedBits);
     },
-    useSelectedContext<C, S>(
-      context: ReactContext<C>,
-      selector: C => S,
-      isEqual: ((S, S) => boolean) | void,
-    ): S {
+    useSelectedContext<C, S>(context: ReactContext<C>, selector: C => S): S {
       currentHookNameInDev = 'useSelectedContext';
       updateHookTypesDev();
       const prevDispatcher = ReactCurrentDispatcher.current;
       ReactCurrentDispatcher.current = InvalidNestedHooksDispatcherOnRerenderInDEV;
       try {
-        return updateSelectedContext(context, selector, isEqual);
+        return updateSelectedContext(context, selector);
       } finally {
         ReactCurrentDispatcher.current = prevDispatcher;
       }
@@ -2855,18 +2824,14 @@ if (__DEV__) {
       mountHookTypesDev();
       return readContext(context, observedBits);
     },
-    useSelectedContext<C, S>(
-      context: ReactContext<C>,
-      selector: C => S,
-      isEqual: ((S, S) => boolean) | void,
-    ): S {
+    useSelectedContext<C, S>(context: ReactContext<C>, selector: C => S): S {
       currentHookNameInDev = 'useSelectedContext';
       warnInvalidHookAccess();
       mountHookTypesDev();
       const prevDispatcher = ReactCurrentDispatcher.current;
       ReactCurrentDispatcher.current = InvalidNestedHooksDispatcherOnMountInDEV;
       try {
-        return mountSelectedContext(context, selector, isEqual);
+        return mountSelectedContext(context, selector);
       } finally {
         ReactCurrentDispatcher.current = prevDispatcher;
       }
@@ -3016,18 +2981,14 @@ if (__DEV__) {
       updateHookTypesDev();
       return readContext(context, observedBits);
     },
-    useSelectedContext<C, S>(
-      context: ReactContext<C>,
-      selector: C => S,
-      isEqual: ((S, S) => boolean) | void,
-    ): S {
+    useSelectedContext<C, S>(context: ReactContext<C>, selector: C => S): S {
       currentHookNameInDev = 'useSelectedContext';
       warnInvalidHookAccess();
       updateHookTypesDev();
       const prevDispatcher = ReactCurrentDispatcher.current;
       ReactCurrentDispatcher.current = InvalidNestedHooksDispatcherOnUpdateInDEV;
       try {
-        return updateSelectedContext(context, selector, isEqual);
+        return updateSelectedContext(context, selector);
       } finally {
         ReactCurrentDispatcher.current = prevDispatcher;
       }
@@ -3178,18 +3139,14 @@ if (__DEV__) {
       updateHookTypesDev();
       return readContext(context, observedBits);
     },
-    useSelectedContext<C, S>(
-      context: ReactContext<C>,
-      selector: C => S,
-      isEqual: ((S, S) => boolean) | void,
-    ): S {
+    useSelectedContext<C, S>(context: ReactContext<C>, selector: C => S): S {
       currentHookNameInDev = 'useSelectedContext';
       warnInvalidHookAccess();
       updateHookTypesDev();
       const prevDispatcher = ReactCurrentDispatcher.current;
       ReactCurrentDispatcher.current = InvalidNestedHooksDispatcherOnUpdateInDEV;
       try {
-        return updateSelectedContext(context, selector, isEqual);
+        return updateSelectedContext(context, selector);
       } finally {
         ReactCurrentDispatcher.current = prevDispatcher;
       }

diff --git a/packages/react-reconciler/src/ReactInternalTypes.js b/packages/react-reconciler/src/ReactInternalTypes.js
@@ -299,11 +299,7 @@ export type Dispatcher = {|
     context: ReactContext<T>,
     observedBits: void | number | boolean,
   ): T,
-  useSelectedContext<C, S>(
-    context: ReactContext<C>,
-    selector: (C) => S,
-    isEqual: ((S, S) => boolean) | void,
-  ): S,
+  useSelectedContext<C, S>(context: ReactContext<C>, selector: (C) => S): S,
   useRef<T>(initialValue: T): {|current: T|},
   useEffect(
     create: () => (() => void) | void,