rename: interfaces composition

interfaces/composition/main.go

@@ -0,0 +1,57 @@
+// 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 (
+	"encoding/json"
+	"fmt"
+	"sort"
+)
+
+func main() {
+	store := list{
+		&book{product{"moby dick", 10}, 118281600},
+		&book{product{"odyssey", 15}, "733622400"},
+		&book{product{"hobbit", 25}, nil},
+		&puzzle{product{"rubik's cube", 5}},
+		&game{product{"minecraft", 20}},
+		&game{product{"tetris", 5}},
+		&toy{product{"yoda", 150}},
+	}
+
+	out, _ := json.Marshal(store)
+	fmt.Println(string(out))
+
+	var (
+		nilItem item
+		nilBook *book
+	)
+
+	fmt.Println("nilBook     ?", nilBook == nil)
+	fmt.Println("nilItem?", nilItem == nil)
+
+	nilItem = nilBook
+	fmt.Println("nilItem?", nilItem == nil)
+
+	books := store[:3]
+
+	books.discount(.5)
+	fmt.Printf("%s\n", store)
+
+	others := store[3:]
+	sort.Sort(byPrice(others))
+	fmt.Printf("\n%s\n", store)
+
+	store = list{books, others}
+	fmt.Printf("\n%s\n", store)
+
+	store.discount(.5)
+	// sort.Sort(sort.Reverse(byPrice(store)))
+	sort.Sort(byName(store))
+	fmt.Println(store)
+}