# EventHandler

`class` in `seedcord` · v0.12.0

<https://docs.seedcord.org/packages/seedcord/0.12.0/classes/event-handler>

Base class for a Discord client event handler.

Pass the event name(s) as the generic, the same one(s) as `@RegisterEvent`. A single-event handler reads `this.event` (the payload tuple) directly. A handler registered for several events branches with `this.match`, keyed by event name, since the union of payload tuples is not directly readable.

```ts
abstract class EventHandler<Names extends ValidNonInteractionKeys>
    extends BaseHandler<ClientEvents[Names]>
    implements Handler
```

## Examples

```ts
\@RegisterEvent([Events.MessageCreate], [Events.MessageUpdate])
class PingPong extends EventHandler<Events.MessageCreate | Events.MessageUpdate> {
    async execute() {
        await this.match({
            [Events.MessageCreate]: (message) => message.reply('pong'),
            [Events.MessageUpdate]: (_oldMessage, edited) => edited.reply('pong')
        });
    }
}
```

## Constructors

### constructor

```ts
EventHandler(
    event: ClientEvents[Names],
    core: Core,
    eventName?: Names
)
```

Constructs a new instance of the `EventHandler` class

## Properties

### event

```ts
protected readonly event: SingleEventPayload<Names>
```

## Methods

### match

```ts
protected async match<Ret>(
    arms: EventMatchArms<Names, Ret>
): Promise<Ret>
```

Run the arm for whichever event fired, when this handler is registered for several events.

Provide one arm per registered event, keyed by its name, and each arm receives that event's payload tuple. A missing arm is a compile error. A single-event handler reads `this.event` directly instead.