feat: struct embedding, enums

go-by-example/enums/enums.go

@@ -0,0 +1,46 @@
+package main
+
+import "fmt"
+
+type ServerState int
+
+const (
+	StateIdle ServerState = iota
+	StateConnected
+	StateError
+	StateRetrying
+)
+
+var stateName = map[ServerState]string{
+	StateIdle:      "idle",
+	StateConnected: "connected",
+	StateError:     "error",
+	StateRetrying:  "retrying",
+}
+
+// String Changes the output value
+func (ss ServerState) String() string {
+	return stateName[ss]
+}
+
+func main() {
+	ns := transition(StateIdle)
+	fmt.Println(ns)
+
+	ns2 := transition(ns)
+	fmt.Println(ns2)
+}
+
+func transition(s ServerState) ServerState {
+	switch s {
+	case StateIdle:
+		return StateConnected
+	case StateConnected, StateRetrying:
+
+		return StateIdle
+	case StateError:
+		return StateError
+	default:
+		panic(fmt.Errorf("unknown state: %s", s))
+	}
+}

go-by-example/structs/struct-embedding/struct-embedding.go

@@ -0,0 +1,40 @@
+package main
+
+import (
+	"fmt"
+)
+
+type base struct {
+	num int
+}
+
+func (b base) describe() string {
+	return fmt.Sprintf("base with num=%v", b.num)
+}
+
+type container struct {
+	base
+	str string
+}
+
+func main() {
+	co := container{
+		base: base{
+			num: 1,
+		},
+		str: "Some name",
+	}
+	fmt.Printf("co={num: %v, str: %v}\n", co.num, co.str)
+
+	fmt.Println("also num: ", co.base.num) // also num but can be without
+
+	// co can also use base method describe since it emebeds base
+	fmt.Println("describe: ", co.describe())
+
+	var d describer = co
+	fmt.Println("describer:", d.describe())
+}
+
+type describer interface {
+	describe() string
+}