Dispatcher.md

Dispatcher

Interface

export declare class Dispatcher extends EventEmitter {
    static isDispatcher(v: any): v is Dispatcher;
    constructor();
    onDispatch(handler: (payload: DispatchedPayload, meta: DispatcherPayloadMeta) => void): () => void;
    dispatch(payload: DispatchedPayload, meta?: DispatcherPayloadMeta): void;
    pipe(toDispatcher: Dispatcher): () => void;
}

---

export declare class Dispatcher extends EventEmitter {

Dispatcher is the central event bus system.

Dispatcher class have these method.

• onDispatch(function(payload){ });
• dispatch(payload);

It is similar with EventEmitter of Node.js But, Dispatcher use payload object as arguments.

Payload

payload object must have type property. Following object is a minimal payload object.

{
    "type": "type"
}

Also, You can put any property to payload object.

{
    "type": "show",
    "value": "value"
}

FAQ

Q. Why Almin use payload object instead emit(key, ...args)?

A. It is for optimization and limitation. If apply emit style, we should cast ...args for passing other dispatcher at every time. So, Almin use payload object instead of it without casting.

---

static isDispatcher(v: any): v is Dispatcher;

if v is instance of Dispatcher, return true

---

constructor();

constructor not have arguments.

---

onDispatch(handler: (payload: DispatchedPayload, meta: DispatcherPayloadMeta) => void): () => void;

Add handler(subscriber) to Dispatcher and return unsubscribe function

Example

const dispatcher = new Dispatcher();
const unsubscribe = dispatcher.onDispatch((payload, meta) => {});
unsubscribe(); // release handler

---

dispatch(payload: DispatchedPayload, meta?: DispatcherPayloadMeta): void;

Dispatch payload to subscribers.

---

pipe(toDispatcher: Dispatcher): () => void;

Delegate payload object to other dispatcher.

Example

const a = new Dispatcher();
const b = new Dispatcher();
// Delegate `a` to `b`
a.pipe(b);
// dispatch and `b` can receive it.
a.dispatch({ type : "a" });

---