interfaces: refactor

interfaces/03-interfaces/main.go

@@ -0,0 +1,52 @@
+// 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
+
+func main() {
+	var (
+		mobydick  = book{title: "moby dick", price: 10}
+		minecraft = game{title: "minecraft", price: 20}
+		tetris    = game{title: "tetris", price: 5}
+		rubik     = puzzle{title: "rubik's cube", price: 5}
+	)
+
+	var store list
+
+	store = append(store, &minecraft, &tetris, mobydick, rubik)
+
+	tetris.discount(.8)
+	// printer(tetris).discount(.8)
+
+	store.print()
+}
+
+/*
+var my list
+
+// + only the `*game` have methods.
+// + `game` doesn't have any methods.
+// + `item` interface couldn't be satisfied with a `game` value.
+// + it can only be satisfied with a `*game` value.
+// my = my.add(minecraft)
+my = append(my, &minecraft)
+my = append(my, &tetris)
+my = append(my, &mobydick)
+
+// interface value stores a pointer to minecraft
+minecraft.discount(.5)
+my.list()
+
+my.discount(.5)
+my.list()
+*/
+
+// ! cannot add mobydick to the store: it's a book type, not a game type.
+// interfaces to the rescue!
+// mobydick := book{title: "moby dick", price: 10}
+// my.add(&mobydick)
+// ----------------------------------------------------------------