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Add ability to specify the external __extends function #2009
Description
Activity
I build
tsc.jsfrom commitf2c98ba95eebfd544aa17d479ed574d59bd7bef1and tried to compile an example from the "Don't emit __extends if one is already in scope #1356" issue. And I got the following result:var __extends = this.__extends || function (d, b) { for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p]; function __() { this.constructor = d; } __.prototype = b.prototype; d.prototype = new __(); }; var M; (function (M) { M.__extends = function () { }; var A = (function () { function A() { } return A; })(); var B = (function (_super) { __extends(B, _super); function B() { _super.apply(this, arguments); } return B; })(A); })(M || (M = {}));Then I found out, that this pull request was not merged to the
masterbranch. But such a solution is unlikely to be help when compiling of external modules with a single export:class A { foo(): void { alert('foo'); } } class B extends A { bar(): void { alert('bar'); } } export = B;I use a single exports when creating a view models in Durandal. Here we need a more comprehensive solution of problem (similar to what I suggested).
By the way, I noticed that even if the
targetoption equals toes6, then class inheritance anyway is implemented by using the__extendsfunction instead of using the native ECMAScript 6 class inheritance.Ah, sorry about that, I also didn't notice we never merged that. There're apparently some additional cases that aren't handled by that PR yet. I logged #2022 for the ES6 part.
Hi, the documentation says that "noEmitHelpers" flag is supported now, but using it with 1.5.0-Beta does not do anything? Is there any particular release I should be using? Thanks.
This was added after 1.5-beta, so it should be in the next release 1.5.2
Thanks for the info! Any estimate on when it will be?
we usually like to stabilize a release for a few weeks before it is released. We are not adding any more features just big fixes at the point. So hopefully soon.
noEmitHelpers is working well for me, but I was curious if there was a pre-created Helpers File that would be easy for me to simply include in my project?
Mike Morton (@mikemorton) there is not one, but here is what i would put:
var __extends = (this && this.__extends) || function (d, b) { for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p]; function __() { this.constructor = d; } d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __()); }; var __decorate = (this && this.__decorate) || function (decorators, target, key, desc) { if (typeof Reflect === "object" && typeof Reflect.decorate === "function") return Reflect.decorate(decorators, target, key, desc); switch (arguments.length) { case 2: return decorators.reduceRight(function(o, d) { return (d && d(o)) || o; }, target); case 3: return decorators.reduceRight(function(o, d) { return (d && d(target, key)), void 0; }, void 0); case 4: return decorators.reduceRight(function(o, d) { return (d && d(target, key, o)) || o; }, desc); } }; var __metadata = (this && this.__metadata) || function (k, v) { if (typeof Reflect === "object" && typeof Reflect.metadata === "function") return Reflect.metadata(k, v); }; var __param = (this && this.__param) || function (paramIndex, decorator) { return function (target, key) { decorator(target, key, paramIndex); } }; var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promise, generator) { return new Promise(function (resolve, reject) { generator = generator.call(thisArg, _arguments); function cast(value) { return value instanceof Promise && value.constructor === Promise ? value : new Promise(function (resolve) { resolve(value); }); } function onfulfill(value) { try { step("next", value); } catch (e) { reject(e); } } function onreject(value) { try { step("throw", value); } catch (e) { reject(e); } } function step(verb, value) { var result = generator[verb](value); result.done ? resolve(result.value) : cast(result.value).then(onfulfill, onreject); } step("next", void 0); }); };
this is handled with the
--noEmitHelpersas stated above.- locked and limited conversation to collaborators
on Jun 18, 2018
Currently when implementing of class inheritance in the output JS-file automatically added the following code:
And calls of the following kind:
In the presence of large amount of TS-files in the project, this leads to a significant increase size of concatenated file (especially when using AMD-modules).
It would be nice to add a new compiler option (it can be called
externalExtendsFunction), which would be allow to specify the name of analog__extendsfunction from external script. For example, if we set to theexternalExtendsFunctionoption a value equal toutil.extends, then the__extendsfunction code will not be generated in the JS-file and its calls will be as follows: