Implement Off

goevent.go

@@ -61,8 +61,19 @@ func (p *Event) On(f interface{}) error {
 	return nil
 }
 
-func (p *Event) Off() {
+func (p *Event) Off(f interface{}) {
-	panic(fmt.Errorf("Off() has not been implemented yet."))
+	fn := reflect.ValueOf(f)
+
+	p.lmu.Lock()
+	defer p.lmu.Unlock()
+	l := len(p.listeners)
+	for i := 0; i < l; i++ {
+		if fn == p.listeners[i] {
+			p.listeners = append(p.listeners[:i], p.listeners[i+1:]...)
+			l--
+			i--
+		}
+	}
 }
 
 func (p *Event) checkFuncSignature(f interface{}) (*reflect.Value, error) {

goevent_test.go

@@ -92,3 +92,38 @@ func TestOnWhenInvalidArgs(t *testing.T) {
 		t.Error("Should return error when different args type. But got nil")
 	}
 }
+
+func TestOff(t *testing.T) {
+	p := goevent.New()
+	i := 0
+	j := 0
+	k := 0
+
+	p.On(func() { j++ })
+	f := func() { i++ }
+	p.On(f)
+	p.On(func() { k++ })
+
+	p.Trigger()
+	if i != 1 {
+		t.Errorf("i expected 1, but got %d", i)
+	}
+	if j != 1 {
+		t.Errorf("j expected 1, but got %d", j)
+	}
+	if k != 1 {
+		t.Errorf("k expected 1, but got %d", k)
+	}
+
+	p.Off(f)
+	p.Trigger()
+	if i != 1 {
+		t.Errorf("i expected 1, but got %d", i)
+	}
+	if j != 2 {
+		t.Errorf("j expected 2, but got %d", j)
+	}
+	if k != 2 {
+		t.Errorf("k expected 2, but got %d", k)
+	}
+}