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add helpers for private-named instance fields #77

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Merged
merged 1 commit into from
Dec 27, 2019
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add helpers for private-named instance fields #77

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2 changes: 2 additions & 0 deletions tslib.d.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -32,3 +32,5 @@ export declare function __asyncValues(o: any): any;
export declare function __makeTemplateObject(cooked: string[], raw: string[]): TemplateStringsArray;
export declare function __importStar<T>(mod: T): T;
export declare function __importDefault<T>(mod: T): T | { default: T };
export declare function __classPrivateFieldGet(receiver: any, privateMap: WeakMap<any, any>): any;
export declare function __classPrivateFieldSet(receiver: any, privateMap: WeakMap<any, any>, value: any): any;
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@Neuroboy23 Neuroboy23 Sep 12, 2019 •
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Should these function declarations be genericized? My instinct is that they should, but I'm not sure which generic form would be appropriate, given the lack of generics in other function declarations in this file.

Each of these methods returns a value of a known type. That would make me want to write the following.

export declare function __classPrivateFieldGet<T>(receiver: any, privateMap: WeakMap<any, T>): T;
export declare function __classPrivateFieldSet<T>(receiver: any, privateMap: WeakMap<any, T>, value: T): T;

However, I don't understand why WeakMap<any, ...> is allowed, given that JS WeakMap.get/set only accept an object as the first parameter. The following TypeScript compiles fine but fails at runtime.

// typescript
const m: WeakMap<any, any> = new WeakMap<any, any>();
m.set(false, true);
// emitted javascript
const m = new WeakMap();
m.set(false, true); // fails at runtime

I would have expected TS's definition to be WeakMap<K extends object, T>. If that were the case, I believe the generic form would be something like the following

export declare function __classPrivateFieldGet<K extends object, T>(receiver: K, privateMap: WeakMap<K, T>): T;
export declare function __classPrivateFieldSet<K extends object, T>(receiver: K, privateMap: WeakMap<K, T>, value: T): T;

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Yes, they should be generic, so I’m doing that in #82.

15 changes: 15 additions & 0 deletions tslib.es6.js
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Original file line number Diff line number Diff line change
Expand Up @@ -196,3 +196,18 @@ export function __importStar(mod) {
export function __importDefault(mod) {
return (mod && mod.__esModule) ? mod : { default: mod };
}

export function __classPrivateFieldGet(receiver, privateMap) {
if (!privateMap.has(receiver)) {
throw new TypeError("attempted to get private field on non-instance");
}
return privateMap.get(receiver);
}

export function __classPrivateFieldSet(receiver, privateMap, value) {
if (!privateMap.has(receiver)) {
throw new TypeError("attempted to set private field on non-instance");
}
privateMap.set(receiver, value);
return value;
}
19 changes: 19 additions & 0 deletions tslib.js
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Expand Up @@ -33,6 +33,8 @@ var __asyncValues;
var __makeTemplateObject;
var __importStar;
var __importDefault;
var __classPrivateFieldGet;
var __classPrivateFieldSet;
(function (factory) {
var root = typeof global === "object" ? global : typeof self === "object" ? self : typeof this === "object" ? this : {};
if (typeof define === "function" && define.amd) {
Expand Down Expand Up @@ -234,6 +236,21 @@ var __importDefault;
return (mod && mod.__esModule) ? mod : { "default": mod };
};

__classPrivateFieldGet = function (receiver, privateMap) {
if (!privateMap.has(receiver)) {
throw new TypeError("attempted to get private field on non-instance");
}
return privateMap.get(receiver);
};

__classPrivateFieldSet = function (receiver, privateMap, value) {
if (!privateMap.has(receiver)) {
throw new TypeError("attempted to set private field on non-instance");
}
privateMap.set(receiver, value);
return value;
}

exporter("__extends", __extends);
exporter("__assign", __assign);
exporter("__rest", __rest);
Expand All @@ -254,4 +271,6 @@ var __importDefault;
exporter("__makeTemplateObject", __makeTemplateObject);
exporter("__importStar", __importStar);
exporter("__importDefault", __importDefault);
exporter("__classPrivateFieldGet", __classPrivateFieldGet);
exporter("__classPrivateFieldSet", __classPrivateFieldSet);
});