如何在 TypeScript 中实现发布订阅模式? [英] How to implement the publish-subscribe pattern in TypeScript?

问题描述

我正在为我的游戏创建一个事件系统，目前我的代码如下所示:

I'm working on creating an events system for my game, and my code currently looks like this:

export const enum ET { Collision, Dying, Damage }

type ActionCallback = (scene: Scene, event: GameEvent) => void;

subscribe(eventType: ET, callback: ActionCallback) {
  this.subscriptions[eventType].push(callback);
}

然后使用这个函数的一些代码的例子是这样的:

And then an example of some code which uses this function is like this:

scene.events.subscribe(ET.Dying, handleEntityDeath);

handleEntityDeath = (scene: Scene, event: DyingEvent) => {
  scene.deleteEntity(event.entity);
}

问题在于 TypeScript 无法编译并显示如下内容:event 的类型必须是 GameEvent 而不是 DyingEvent.

The problem is that TypeScript fails to compile and says something like: event's type must be GameEvent and not DyingEvent.

基本上，我需要一种方法来链接"ET.Dying 和 DyingEvent，但我不知道该怎么做.我想如果我能做到这一点，那么我可以像上面这样的事件处理程序，如果第一个参数是类似 ET.Dying 的东西，它只会编译，第二个参数是一个回调，它需要一个 死亡事件.如果回调具有 DamageEvent 参数，我希望它无法编译，如果这是有道理的.

Basically, I need a way to "link" ET.Dying and DyingEvent, but I'm not sure how to do it. I think if I can accomplish this, then I can event handlers like the above where it will only compile if the first parameter is something like ET.Dying and the second parameter is a callback which takes a DyingEvent. I would want it to fail to compile if the callback instead had a DamageEvent parameter, if that makes sense.

这可以做到吗，如果可以，怎么做?

Can this be done, and if so, how?

推荐答案

想通了:

interface EventMap {
  [ET.Collision]: CollisionEvent;
  [ET.Dying]: DyingEvent;
  // etc
}

subscribe = <T extends ET>(eventType: T, callback: (scene: Scene, event: EventMap[T]) => void) => {
  this.subscriptions[eventType].push(callback);
}

// Example calling code below here:

scene.events.subscribe(ET.Dying, handleEntityDeath);

handleEntityDeath = (scene: Scene, event: DyingEvent) => {
  scene.deleteEntity(event.entity);
}

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