Add 'Once' Event function

event.go

@@ -1,14 +1,19 @@
 package gobot
 
+type callback struct {
+	f    func(interface{})
+	once bool
+}
+
 type Event struct {
 	Chan      chan interface{}
-	Callbacks []func(interface{})
+	Callbacks []callback
 }
 
 func NewEvent() *Event {
 	e := &Event{
 		Chan:      make(chan interface{}, 1),
-		Callbacks: []func(interface{}){},
+		Callbacks: []callback{},
 	}
 	go func() {
 		for {
@@ -26,9 +31,14 @@ func (e *Event) Write(data interface{}) {
 }
 
 func (e *Event) Read() {
+	tmp := []callback{}
 	for s := range e.Chan {
-		for _, f := range e.Callbacks {
-			go f(s)
+		for i := range e.Callbacks {
+			go e.Callbacks[i].f(s)
+			if !e.Callbacks[i].once {
+				tmp = append(tmp, e.Callbacks[i])
+			}
 		}
+		e.Callbacks = tmp
 	}
 }

platforms/firmata/firmata.go

@@ -112,18 +112,15 @@ func (b *board) connect() {
 }
 
 func (b *board) initBoard() {
-	gobot.On(b.events["firmware_query"], func(data interface{}) {
-		b.events["firmware_query"] = gobot.NewEvent()
+	gobot.Once(b.events["firmware_query"], func(data interface{}) {
 		b.queryCapabilities()
 	})
 
-	gobot.On(b.events["capability_query"], func(data interface{}) {
-		b.events["capability_query"] = gobot.NewEvent()
+	gobot.Once(b.events["capability_query"], func(data interface{}) {
 		b.queryAnalogMapping()
 	})
 
-	gobot.On(b.events["analog_mapping_query"], func(data interface{}) {
-		b.events["analog_mapping_query"] = gobot.NewEvent()
+	gobot.Once(b.events["analog_mapping_query"], func(data interface{}) {
 		b.togglePinReporting(0, high, reportDigital)
 		<-time.After(50 * time.Millisecond)
 		b.togglePinReporting(1, high, reportDigital)
@@ -270,7 +267,7 @@ func (b *board) process(data []byte) {
 				pin := b.pins[pinNumber]
 				if byte(pin.mode) == input {
 					pin.value = int((portValue >> (byte(i) & 0x07)) & 0x01)
-					gobot.Publish(fmt.Sprintf("digital_read_%v", pinNumber),
+					gobot.Publish(b.events[fmt.Sprintf("digital_read_%v", pinNumber)],
 						[]byte{byte(pin.value & 0xff)})
 				}
 			}
@@ -301,7 +298,7 @@ func (b *board) process(data []byte) {
 							}
 						}
 						b.pins = append(b.pins, pin{modes, output, 0, 0})
-						b.Events[fmt.Sprintf("digital_read_%v", len(b.pins)-1)] = gobot.NewEvent()
+						b.events[fmt.Sprintf("digital_read_%v", len(b.pins)-1)] = gobot.NewEvent()
 						supportedModes = 0
 						n = 0
 						continue
@@ -360,7 +357,7 @@ func (b *board) process(data []byte) {
 						byte(currentBuffer[i])|byte(currentBuffer[i+1])<<7,
 					)
 				}
-				gobo.Publish(b.events["i2c_reply"], i2cReply)
+				gobot.Publish(b.events["i2c_reply"], i2cReply)
 			case firmwareQuery:
 				name := []byte{}
 				for _, val := range currentBuffer[4:(len(currentBuffer) - 1)] {

platforms/firmata/firmata_adaptor.go

@@ -77,7 +77,7 @@ func (f *FirmataAdaptor) DigitalRead(pin string) int {
 	f.board.togglePinReporting(byte(p), high, reportDigital)
 	f.board.readAndProcess()
 
-	gobot.On(f.board.events[fmt.Sprintf("digital_read_%v", pin)], func(data interface{}) {
+	gobot.Once(f.board.events[fmt.Sprintf("digital_read_%v", pin)], func(data interface{}) {
 		ret <- int(data.([]byte)[0])
 	})
 
@@ -94,7 +94,7 @@ func (f *FirmataAdaptor) AnalogRead(pin string) int {
 	f.board.togglePinReporting(byte(p), high, reportAnalog)
 	f.board.readAndProcess()
 
-	gobot.On(f.board.events[fmt.Sprintf("analog_read_%v", pin)], func(data interface{}) {
+	gobot.Once(f.board.events[fmt.Sprintf("analog_read_%v", pin)], func(data interface{}) {
 		b := data.([]byte)
 		ret <- int(uint(b[0])<<24 | uint(b[1])<<16 | uint(b[2])<<8 | uint(b[3]))
 	})
@@ -121,8 +121,8 @@ func (f *FirmataAdaptor) I2cRead(size uint) []byte {
 
 	f.board.readAndProcess()
 
-	gobot.On(f.board.events["i2c_reply"], func(data interface{}) {
-		ret <- data.(i2CReply)["data"]
+	gobot.Once(f.board.events["i2c_reply"], func(data interface{}) {
+		ret <- data.(map[string][]byte)["data"]
 	})
 
 	return <-ret

utils.go

@@ -31,7 +31,14 @@ func Publish(e *Event, val interface{}) {
 }
 
 func On(e *Event, f func(s interface{})) {
-	e.Callbacks = append(e.Callbacks, f)
+	e.Callbacks = append(e.Callbacks, callback{f, false})
+	//e.Callbacks[f] = false
+}
+
+func Once(e *Event, f func(s interface{})) {
+	//e.Callbacks = append(e.Callbacks, f)
+	e.Callbacks = append(e.Callbacks, callback{f, true})
+	//e.Callbacks[f] = true
 }
 
 func Rand(max int) int {