Lightweight event management, dispatch tool library implemented by Go

event - Lightweight event management, dispatch tool library implemented by Go

• Support for custom definition event objects
• Support for adding multiple listeners to an event
• Supports setting the priority of the event listener. The higher the priority, the higher the trigger.
• Support for a set of event listeners based on the event name prefix PREFIX.*.
  • add app.* event listen, trigger app.run app.end, Both will trigger the app.* event at the same time
• Support for using the wildcard * to listen for triggers for all events
• Complete unit testing, unit coverage > 95%

Repo and doc

• Github: https://github.com/gookit/event
• Godoc for github

Install

go install github.com/gookit/event

Quick start

package main

import (
    "fmt"

    "github.com/gookit/event"
)

func main() {
    // Register event listener
    event.On("evt1", event.ListenerFunc(func(e event.Event) error {
        fmt.Printf("handle event: %s\n", e.Name())
        return nil
    }), event.Normal)

    // Register multiple listeners
    event.On("evt1", event.ListenerFunc(func(e event.Event) error {
        fmt.Printf("handle event: %s\n", e.Name())
        return nil
    }), event.High)

    // ... ...

    // Trigger event
    // Note: The second listener has a higher priority, so it will be executed first.
    event.MustFire("evt1", event.M{"arg0": "val0", "arg1": "val1"})
}

Note: The second listener has a higher priority, so it will be executed first.

Using the wildcard

Register event listener and name end with wildcard *:

func main() {
    dbListener1 := event.ListenerFunc(func(e event.Event) error {
        fmt.Printf("handle event: %s\n", e.Name())
        return nil
    })

    event.On("app.db.*", dbListener1, event.Normal)
}

Trigger events on other logic:

func doCreate() {
    // do something ...
    // Trigger event
    event.MustFire("app.db.create", event.M{"arg0": "val0", "arg1": "val1"})
}

func doUpdate() {
    // do something ...
    // Trigger event
    event.MustFire("app.db.update", event.M{"arg0": "val0"})
}

Like the above, triggering the app.db.create app.db.update event
will trigger the execution of the dbListener1 listener.

Write event listeners

Using anonymous functions

You can use anonymous function for quick write an event lister.

package mypgk

import (
    "fmt"

    "github.com/gookit/event"
)

var fnHandler = func(e event.Event) error {
    fmt.Printf("handle event: %s\n", e.Name())
    return nil
}

func Run() {
    // register
    event.On("evt1", event.ListenerFunc(fnHandler), event.High)
}

Using the structure method

You can use struct write an event lister, and it should implementation interface event.Listener.

interface:

// Listener interface
type Listener interface {
    Handle(e Event) error
}

example:

Implementation interface event.Listener

package mypgk

import "github.com/gookit/event"

type MyListener struct {
    // userData string
}

func (l *MyListener) Handle(e event.Event) error {
    e.Set("result", "OK")
    return nil
}

Register multiple event listeners

Can implementation interface event.Subscriber for register
multiple event listeners at once.

interface:

// Subscriber event subscriber interface.
// you can register multi event listeners in a struct func.
type Subscriber interface {
    // SubscribedEvents register event listeners
    // key: is event name
    // value: can be Listener or ListenerItem interface
    SubscribedEvents() map[string]interface{}
}

example

Implementation interface event.Subscriber

package mypgk

import (
    "fmt"

    "github.com/gookit/event"
)

type MySubscriber struct {
    // ooo
}

func (s *MySubscriber) SubscribedEvents() map[string]interface{} {
    return map[string]interface{}{
        "e1": event.ListenerFunc(s.e1Handler),
        "e2": event.ListenerItem{
            Priority: event.AboveNormal,
            Listener: event.ListenerFunc(func(e Event) error {
                return fmt.Errorf("an error")
            }),
        },
        "e3": &MyListener{},
    }
}

func (s *MySubscriber) e1Handler(e event.Event) error {
    e.Set("e1-key", "val1")
    return nil
}

Write custom events

If you want to customize the event object or define some fixed event information in advance,
you can implement the event.Event interface.

interface:

// Event interface
type Event interface {
    Name() string
    // Target() interface{}
    Get(key string) interface{}
    Add(key string, val interface{})
    Set(key string, val interface{})
    Data() map[string]interface{}
    SetData(M) Event
    Abort(bool)
    IsAborted() bool
}

examples:

package mypgk

import "github.com/gookit/event"

type MyEvent struct {
    event.BasicEvent
    customData string
}

func (e *MyEvent) CustomData() string {
    return e.customData
}

Usage:

e := &MyEvent{customData: "hello"}
e.SetName("e1")
event.AddEvent(e)

// add listener
event.On("e1", event.ListenerFunc(func(e event.Event) error {
    fmt.Printf("custom Data: %s\n", e.(*MyEvent).CustomData())
    return nil
}))

// trigger
event.Fire("e1", nil)
// OR
// event.FireEvent(e)

Main method

• On/Listen(name string, listener Listener, priority ...int) Register event listener
• Subscribe/AddSubscriber(sbr Subscriber) Subscribe to support registration of multiple event listeners
• Trigger/Fire(name string, params M) (error, Event) Trigger event by name and params
• MustTrigger/MustFire(name string, params M) Event Trigger event, there will be panic if there is an error
• FireEvent(e Event) (err error) Trigger an event based on a given event instance
• FireBatch(es ...interface{}) (ers []error) Trigger multiple events at once
• AsyncFire(e Event) Async fire event by 'go' keywords