如何在JavaScript类中编写生成器?

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通常，我写这样的代码:

Usually, I write code like this:

//definition exports.getReply = function * (msg){ //... return reply; } //usage var msg = yield getReply ('hello');

但是如何在es6类中编写和使用生成器?我试过了:

but how can I write and use a generator in and out of an es6 class? I tried this:

class Reply{ *getReply (msg){ //... return reply; } *otherFun(){ this.getReply(); //`this` seem to have no access to `getReply` } } var Reply = new Reply(); Reply.getReply(); //out of class,how can I get access to `getReply`?

我也尝试过:

class Reply{ getReply(){ return function*(msg){ //... return reply; } } }

这两种方法似乎都是错误的答案.那么如何正确在类中编写生成器函数呢?

All of these two methods seem to be wrong answers. So how can I write generator functions in a class correctly?

推荐答案

添加更多示例. 您的class定义几乎是正确的.错误是在实例化var Reply = new Reply();中.这将尝试重新定义分配给类名称的变量.同样，generator函数也应yield起作用.我详细说明了一些OP代码以显示工作示例.

Add more examples. Your class definition is (almost) correct.The error was in instantiation var Reply = new Reply();. This tries to redefine variable assigned to class name. Also generator function is expected to yield something. I elaborated a little OP code to show working example.

class Reply { //added for test purpose constructor(...args) { this.args = args; } * getReply(msg) { for (let arg in this.args) { let reply = msg + this.args[arg]; //generator should yield something yield reply; } //next call returns (yields) {done:true,value:undefined} } * otherFun() { yield this.getReply('Nice to meet you '); //yields Generator object yield this.getReply('See you '); //Yes, this can access //next call yields {done:true, value:undefined} } * evenMore() { yield* this.getReply('I miss you '); //yields generator result(s) yield* this.getReply('I miss you even more '); } } //now test what we have const reply = new Reply('Peter', 'James', 'John'); //let and var here are interchangeable because of Global scope var r = reply.getReply('Hello '); var msg = r.next(); //{done:false,value:"..."} while (!msg.done) { console.log(msg.value); msg = r.next(); } var other = reply.otherFun(); var o = other.next(); //{done:false,value:Generator} while (!o.done) { let gen = o.value; msg = gen.next(); while (!msg.done) { console.log(msg.value); msg = gen.next(); } o = other.next(); } var more = reply.evenMore(); msg = more.next(); while (!msg.done) { console.log(msg.value); msg = more.next(); } //update of 1/12/2019 //more examples for (let r of reply.getReply('for ')) { console.log(r); } for (let r of reply.evenMore()) { console.log(r); } //note that the following doesn't work because of lack of star (*) inside the generator function for (let r of reply.otherFun()) { console.log(r); }

更新1/12/2019

如@BugBuddy所建议，for..of循环看起来更好(但并非在所有情况下都有效).查看摘要中的更新行.

As suggested by @BugBuddy for..of loop looks even nicer (But doesn't work in all cases). See updated lines in the snippet.