限制从 EventEmitter3 发出

Question

与接受的答案相关：https://stackoverflow.com/a/63639280/17928771

EventEmitter3 是一个通用类，它采用（作为一个示例）事件/处理程序的接口。我正在尝试将

IRaceManager

emit

s 限制为

IRaceEvents

。我试过：

尝试 1.

class POSRaceManager implements IRaceManager extends EventEmitter<IRaceEvents> {}

let raceManager: IRaceManager = new POSRaceManager();
raceManager.emit('moo'); // error, no `emit` on IRaceManager

尝试 2.

interface IRaceManager extends EventEmitter<IRaceEvents> {} // TS2749: 'EventEmitter' refers to a value, but is being used as a type here. Did you mean 'typeof EventEmitter'?

以下尝试有效，但不会将

emit

或

on

限制为 IRaceEvents（或 IRaceEvents 的扩展）

尝试 3.

这失败了：

type RaceEventEmitterType<T extends IRaceEvents> = InstanceType<typeof EventEmitter>;
type IRaceManager<T extends IRaceEvents> = RaceEventEmitterType<T>;

let raceManager: IRaceManager = new POSRaceManager<IRaceEvents>;
raceManager.emit("moo"); // no error because of `InstanceType<typeof EventEmitter>`

最后的尝试。

type RaceEventEmitterType<T extends IRaceEvents> = InstanceType<typeof EventEmitter<IRaceEvents>>; // Need to investigate what this does, actually. I overlooked a syntax error before.

有什么想法可以限制从

raceManager<?>

到

T extends IRaceEvents

的排放量吗？

编辑：

我目前解决了以下问题（有效，我只是想知道是否有办法解决上述问题）：

type RaceEventEmitter<T extends IRaceEvents> = InstanceType<typeof EventEmitter>;
type IRaceManager<T extends IRaceEvents> = RaceEventEmitter<T>;
class POSRaceManager extends EventEmitter<IRaceEvents> implements IRaceManager<IRaceEvents>;

Answer 1

“哪一部分你不明白？”

答案：核心概念？ （弓箭手语录）

这是一个粗略的学习曲线，但最终有了一个向前推进的解决方案：

type TRaceEvents = {
    raceUpdate: (race: IRace | null) => void;
}

// Extending EventEmitter is essential to ensure the implementation properly
//  extends `EventEmitter`; however, `extends EventEmitter<TRaceEvents>` has
//  no additional affect (though is preferred as the Runner could fail to 
//  function properly if the impl isn't Typed with `TRaceEvents`)
interface IRaceManager extends EventEmitter {
  race: IRace;
  start() => void;
}

class StandardRaceManager extends EventEmitter<TRaceEvents> implements IRaceManager {
  constructor(public race: IRace) { super(); }
}

const standardRace: TRaceManager = new StandardRaceManager();
standardRace.on("raceUpdate", race => console.log(race));
standardRace.start();
standardRace.emit("raceUpdate", race);

以下没有编译错误或运行时错误（并且按预期工作），但 WebStorm 抱怨如下：

class StandardRaceManager extends EventEmitter<TRaceEvents> implements IRaceManager {
  constructor(public race: IRace) {
    super();
    // `this.race`: Argument type IRace is not assignable to parameter type any
    this.emit("raceUpdate", this.race);
  }