update: interfaces lecture

interfaces/04-interfaces/power/main.go

@@ -0,0 +1,64 @@
+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import (
+	"fmt"
+	"math/rand"
+	"time"
+)
+
+// Socket has the power!
+type Socket struct {
+	power int
+}
+
+// Plug a device to draw power from the `Socket`
+func (s *Socket) Plug(device PowerDrawer) {
+	n := rand.Intn(50)
+	s.power -= n
+	device.Draw(n)
+}
+
+// PowerDrawer can be any type that can be powered
+type PowerDrawer interface {
+	Draw(power int)
+}
+
+// -----
+
+// Kettle can be powered
+type Kettle struct{}
+
+// Draw power to a Kettle
+func (Kettle) Draw(power int) {
+	fmt.Printf("Kettle is drawing %dkW of electrical power.\n", power)
+}
+
+// Mixer can be powered
+type Mixer struct{}
+
+// Draw power to a Mixer
+func (Mixer) Draw(power int) {
+	fmt.Printf("Mixer is drawing %dkW of electrical power.\n", power)
+}
+
+// -----
+
+func main() {
+	rand.Seed(time.Now().UnixNano())
+
+	kettle := Kettle{}
+	mixer := Mixer{}
+
+	socket := &Socket{100}
+	socket.Plug(kettle)
+	socket.Plug(mixer)
+
+	fmt.Printf("Socket's available power is %d kW.\n", socket.power)
+}