Attempt to fix 734: introduce array.get / set

package.json

@@ -1,6 +1,6 @@
 {
   "name": "mobx",
-  "version": "3.0.1",
+  "version": "3.0.1-fix734",
   "description": "Simple, scalable state management.",
   "main": "lib/mobx.js",
   "typings": "lib/mobx.d.ts",

src/mobx.ts

@@ -67,6 +67,7 @@ import { spyReport, spyReportEnd, spyReportStart, isSpyEnabled } from "./core/sp
 import { Lambda } from "./utils/utils";
 import { isComputingDerivation } from "./core/derivation";
 import { setReactionScheduler, onReactionError } from "./core/reaction";
+import { reserveArrayBuffer } from "./types/observablearray";
 
 export const extras = {
 	allowStateChanges,
@@ -79,6 +80,7 @@ export const extras = {
 	isComputingDerivation,
 	isSpyEnabled,
 	onReactionError,
+	reserveArrayBuffer, // See #734
 	resetGlobalState,
 	shareGlobalState,
 	spyReport,

src/types/observablearray.ts

@@ -388,6 +388,16 @@ export class ObservableArray<T> extends StubArray {
 		this.$mobx.atom.reportObserved();
 		return Array.prototype.toLocaleString.apply(this.$mobx.values, arguments);
 	}
+
+	// See #734, in case property accessors are unreliable...
+	get(index: number): T {
+		return (ALL_INDEX_DESCRIPTORS[index].get as any).call(this);
+	}
+
+	// See #734, in case property accessors are unreliable...
+	set(index: number, value: T): void {
+		(ALL_INDEX_DESCRIPTORS[index].set as any).call(this, value);
+	}
 }
 
 declareIterator(ObservableArray.prototype, function() {
@@ -403,6 +413,7 @@ makeNonEnumerable(ObservableArray.prototype, [
 	"observe",
 	"clear",
 	"concat",
+	"get",
 	"replace",
 	"toJS",
 	"toJSON",
@@ -411,6 +422,7 @@ makeNonEnumerable(ObservableArray.prototype, [
 	"splice",
 	"push",
 	"pop",
+	"set",
 	"shift",
 	"unshift",
 	"reverse",
@@ -465,14 +477,18 @@ const ENTRY_0 = {
 	get: createArrayGetter(0)
 };
 
+const ALL_INDEX_DESCRIPTORS: PropertyDescriptor[] = [];
+
 function createArrayBufferItem(index: number) {
 	const set = createArraySetter(index);
 	const get = createArrayGetter(index);
-	Object.defineProperty(ObservableArray.prototype, "" + index, {
+	const descriptor = {
 		enumerable: false,
 		configurable: true,
 		set, get
-	});
+	};
+	ALL_INDEX_DESCRIPTORS[index] = descriptor;
+	Object.defineProperty(ObservableArray.prototype, "" + index, descriptor);
 }
 
 function createArraySetter(index: number) {
@@ -522,7 +538,7 @@ function createArrayGetter(index: number) {
 	};
 }
 
-function reserveArrayBuffer(max: number) {
+export function reserveArrayBuffer(max: number) {
 	for (let index = OBSERVABLE_ARRAY_BUFFER_SIZE; index < max; index++)
 		createArrayBufferItem(index);
 	OBSERVABLE_ARRAY_BUFFER_SIZE = max;

test/api.js

@@ -60,6 +60,7 @@ test('correct api should be exposed', function(t) {
 			'isComputingDerivation',
 			'isSpyEnabled',
 			'onReactionError',
+			'reserveArrayBuffer',
 			'resetGlobalState',
 			'setReactionScheduler',
 			'shareGlobalState',

test/array.js

@@ -87,6 +87,10 @@ test('test1', function(t) {
 
 	t.equal(JSON.stringify(a), "[3,1,2]");
 
+	t.equal(a.get(1), 1);
+	a.set(2, 4);
+	t.equal(a.get(2), 4);
+
 //	t.deepEqual(Object.keys(a), ['0', '1', '2']); // ideally....
 	t.deepEqual(Object.keys(a), []);
 

test/perf/perf.txt

@@ -1,51 +1,51 @@
 
-One observers many observes one - Started/Updated in 60/34 ms.
-500 props observing sibling -  Started/Updated in 3/11 ms.
-Late dependency change - Updated in 135ms.
-Unused computables -   Updated in 0 ms.
-Unused observables -  Updated in 25 ms.
-Array reduce -  Started/Updated in 57/44 ms.
-Array loop -  Started/Updated in 127/231 ms.
-Order system batched: false tracked: true  Started/Updated in 473/37 ms.
-Order system batched: true tracked: true  Started/Updated in 102/28 ms.
-Order system batched: false tracked: false  Started/Updated in 117/37 ms.
-Order system batched: true tracked: false  Started/Updated in 118/35 ms.
+One observers many observes one - Started/Updated in 50/22 ms.
+500 props observing sibling -  Started/Updated in 6/2 ms.
+Late dependency change - Updated in 59ms.
+Unused computables -   Updated in 1 ms.
+Unused observables -  Updated in 10 ms.
+Array reduce -  Started/Updated in 28/26 ms.
+Array loop -  Started/Updated in 113/170 ms.
+Order system batched: false tracked: true  Started/Updated in 701/76 ms.
+Order system batched: true tracked: true  Started/Updated in 180/76 ms.
+Order system batched: false tracked: false  Started/Updated in 235/86 ms.
+Order system batched: true tracked: false  Started/Updated in 116/33 ms.
 
-Create array -  Created in 552ms.
+Create array -  Created in 261ms.
 
-Create array (non-recursive)  Created in 297ms.
-Observable with many observers  + dispose: 768ms
-expensive sort: created 2787
-expensive sort: updated 12518
-expensive sort: disposed561
-native plain sort: updated 1087
-computed memoization 1ms
-create folders 0ms.
-create displayfolders 1ms.
-create text 471ms.
+Create array (non-recursive)  Created in 45ms.
+Observable with many observers  + dispose: 1627ms
+expensive sort: created 4714
+expensive sort: updated 11440
+expensive sort: disposed412
+native plain sort: updated 920
+computed memoization 0ms
+create folders 1ms.
+create displayfolders 0ms.
+create text 225ms.
 collapse folder 1ms.
-uncollapse folder 1ms.
-change name of folder 498ms.
-search 103ms.
-unsearch 438ms.
+uncollapse folder 0ms.
+change name of folder 221ms.
+search 49ms.
+unsearch 211ms.
 reactive folder tree [total]
- 1517ms.
-create folders 21ms.
-create displayfolders 1ms.
-create text 51ms.
-collapse folder 2ms.
-uncollapse folder 5ms.
-change name of folder 10ms.
-search 15ms.
-unsearch 24ms.
+ 709ms.
+create folders 29ms.
+create displayfolders 3ms.
+create text 112ms.
+collapse folder 6ms.
+uncollapse folder 10ms.
+change name of folder 17ms.
+search 47ms.
+unsearch 37ms.
 reactive folder tree [total]
- 131ms.
-create boxes 89ms.
-mutations 523ms.
-total 625ms.
-create boxes 90ms.
-mutations 928ms.
-total 1084ms.
+ 263ms.
+create boxes 125ms.
+mutations 412ms.
+total 554ms.
+create boxes 128ms.
+mutations 958ms.
+total 1158ms.
 
 
-Completed performance suite in 25.475 sec.
+Completed performance suite in 25.2 sec.