# Evt.asPostable(evt)

## Deprecated

Evt.asPostable() will be removed in the next major of Evt.  

If you are currently using it, consider refactoring your code so that you don't need it anymore. 

See [this newer example](/migrating_from_events.md#composition-recommended-approach). ( that replace [the older one](https://github.com/garronej/evt/blob/2069fe58663433c3042e00a9b72622e244b01721/extending_evt.md?plain=1#L71-L138)).

<pre class="language-diff"><code class="lang-diff"> import { Evt } from "evt";
 import type {
   NonPostableEvt,
<strong>+  ToPostableEvt
</strong> } from "evt";

 const evtMsg: NonPostableEvt&#x3C;string> = new Evt();

<strong>-Evt.toPostable(evtMsg).post("foo");
</strong><strong>+(evtMsg as ToPostable&#x3C;typeof evtMsg>).post("foo");
</strong></code></pre>

## Usecase

{% hint style="info" %}
Evt.asNonPostable() is the identity function with special type annotation
{% endhint %}

{% hint style="warning" %}
Use this method only on`Evt` you instantiated yourself. Not as a hack to trigger events on `Evt` that have been exposed as non-postable by an API.
{% endhint %}

To invoke `post()` on a `NonPostableEvt` or a `StatefullReadonlyEvt`.

Without this method this would be the way for a class to expose `Evt` that are posted internally and exposed to be listened.

```typescript
import { Evt } from "evt";

class Socket2 {

    private readonly _evtIsConnected= Evt.create(false);
    private readonly _evtMessage= Evt.create<Uint8Array>();

    readonly evtIsConnected= Evt.asNonPostable(this._evtIsConnected);
    readonly evtMessage= Evt.asNonPostable(this._evtMessage);

    /* 
        OR, more explicit but require to repeat the types and to
        import type { StatefulReadonlyEvt, NonPostableEvt } from "evt";

    readonly evtIsConnected: StatefulReadonlyEvt<boolean>= this._evtIsConnected;
    readonly evtMessage: NonPostableEvt<Uint8Array> = this._evtMessage;
    */

    constructor(){

        this._evtIsConnected.state = true;
        this._evtMessage.post(new Uint8Array(111));

    }

}
```

Now it can be frustrating to have to store a private property only to call post on a object that we know is postable. Here is were this method come in handy:

```typescript
class Socket {

    readonly evtIsConnected= Evt.asNonPostable(Evt.create(false));
    readonly evtMessage= Evt.asNonPostable(Evt.create<Uint8Array>());

    constructor(){

        Evt.asPostable(this.evtIsConnected).state = true;
        Evt.asPostable(this.evtMessage).post(new Uint8Array(111));

    }


}
```


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