Event Emitter

GoNest includes a lightweight pub/sub event system for decoupling components.

Setup

emitter := gonest.NewEventEmitter()

// Register as a provider
gonest.ProvideValue[*gonest.EventEmitter](emitter)

Listening

emitter.On("order.created", func(data any) error {
    order := data.(*Order)
    log.Printf("New order: %d", order.ID)
    return sendConfirmationEmail(order)
})

Emitting

func (s *OrdersService) Create(dto CreateOrderDto) (*Order, error) {
    order := // ... create order
    s.emitter.Emit("order.created", order)
    return order, nil
}

Async Events

// Fire and forget — handlers run in goroutines
s.emitter.EmitAsync("analytics.pageview", pageData)

API

Method	Description
`On(event, handler)`	Register handler
`Emit(event, data)`	Synchronous emit
`EmitAsync(event, data)`	Async emit (goroutines)
`RemoveAll(event)`	Remove all handlers
`ListenerCount(event)`	Count handlers