dangdungcntt / mint

🍃 Tiny event emitter built on generics

Mint 🍃

Tiny generic event emitter.

• Very simple: mint has 3 exported functions and 1 type
• Type safe: built on generics
• Fast: does not use reflection
• Independant: has no external dependencies

Get

go get github.com/btvoidx/mint

Use

// Create an emitter
e := new(mint.Emitter) // or &mint.Emmiter{}

// Create a consumer
func OnMyEvent(MyEvent) {
	// do stuff with the value
}

// Subscribe
off := mint.On(e, OnMyEvent)
defer off() // don't forget to unsubsribe later!

// ...

// In some other place
mint.Emit(e, MyEvent{Msg: "Hi", FromID: 1})
mint.Emit(e, MyEvent{Msg: "Hello indeed", FromID: 2})

By importing the package as "github.com/btvoidx/mint/context" you can access contextful api.

import "github.com/btvoidx/mint/context"

ctx, cancel := context.WithTimeout(context.Background(), time.Second)
defer cancel()

// Not all consumers may receive the message due to timeout,
// but Emit does wait for the active consumer to finish.
err := mint.Emit(e, ctx, MyEvent{Msg: "A message"})

// err is always ctx.Err()
if err != ctx.Err() {	/* unreachable code */ }

Both versions can operate on the same mint.Emitter instance, as contextless api just wraps the contextful one with context.Background().

// MyEvent consumers will receive both events.
mintctx.Emit(e, ctx, MyEvent{Msg: "A message"})
mint.Emit(e, MyEvent{Msg: "A message"}) // uses context.Background()

If you prefer channel-based consumers you can create a wrapper for mint.On so that it forwards all data to a channel.

func MyOn[T any](e *mint.Emitter) (<-ch T, off func()) {
	ch := make(chan T)
	off := mint.On(e, func(v T) {
		go func() { ch <- v }
	})

	return ch, func() {
		off()
		// drain channel so pending emits don't panic
		for {
			select {
			case <-ch:
			default:
				close(ch)
				return
			}
		}
	}
}

// Use it like so
ch, off := MyOn[MyEvent](e)
defer off()

for event := range ch {
	// deal with incoming data
}

For additional examples see mint_test.go.

Reporting issues

If you have questions or problems just open a new issue.