event

type Dispatcher interface {
	// register event quickly
	Register(eventType string, handler Handler)

	//add event listener
	AddListener(eventType string, listener *Listener)

	//remove event listener
	RemoveListener(eventType string, listener *Listener) bool

	//check listener is or not exist
	HasListener(eventType string) bool

	//dispatch event
	DispatchEvent(event Event) bool

	// trigger event, simple than DispatchEvent
	Trigger(eventType string, params interface{}) bool
}

type Event struct {
	// dispatcher
	Dispatcher Dispatcher
	// name
	Type string
	// event params
	Params interface{}
}

type Handler func(ev Event)

type Listener struct {
	Handler Handler
}

type Saver struct {
	// event name
	Type string
	// event listeners
	Listeners []*Listener
}