Исходники и презентации

lessons/functions/lazy_evaluation/main.go

@@ -0,0 +1,31 @@
+package main
+
+import (
+	"fmt"
+)
+
+type LazyMap func() map[string]string
+
+func Make(ctr func() map[string]string) LazyMap {
+	var initialized bool
+	var data map[string]string
+	return func() map[string]string {
+		if !initialized {
+			data = ctr()
+			initialized = true
+			ctr = nil // for GC
+		}
+
+		return data
+	}
+}
+
+func main() {
+	data := Make(func() map[string]string {
+		return make(map[string]string)
+	})
+
+	fmt.Println(data())
+	data()["key"] = "value"
+	fmt.Println(data())
+}