update: interfaces

interfaces/04-interfaces/book.go

@@ -1,24 +0,0 @@
-// 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"
-
-type book struct {
-	title string
-	price float64
-}
-
-func (b book) print() {
-	fmt.Printf("%-15s: $%.2f \n", b.title, b.price)
-}
-
-// TODO: NEW
-func (b book) total() float64 {
-	return b.price
-}

interfaces/04-interfaces/game.go

@@ -1,28 +0,0 @@
-// 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"
-
-type game struct {
-	title string
-	price float64
-}
-
-func (g *game) print() {
-	fmt.Printf("%-15s: $%.2f\n", g.title, g.price)
-}
-
-func (g *game) discount(ratio float64) {
-	g.price *= (1 - ratio)
-}
-
-// TODO: NEW
-func (g *game) total() float64 {
-	return g.price
-}

interfaces/04-interfaces/list.go

@@ -1,71 +0,0 @@
-// 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"
-
-// TODO: NEW
-type printer interface {
-	print()
-}
-
-// TODO: NEW
-type pricer interface {
-	total() float64
-}
-
-// TODO: NEW
-// interface embedding
-type item interface {
-	printer
-	pricer
-}
-
-// a slice of item interface values
-type list []item
-
-func (l list) list() {
-	// `list` acts like a `[]game`
-	if len(l) == 0 {
-		fmt.Println("Sorry. Our store is closed. We're waiting for the delivery 🚚.")
-		return
-	}
-
-	fmt.Printf("My Store:\n")
-	fmt.Printf("---------\n")
-	for _, it := range l {
-		it.print()
-	}
-
-	// TODO: NEW
-	fmt.Printf("\nGROSS: $%.2f\n", l.total())
-}
-
-// TODO: NEW
-func (l list) total() (gross float64) {
-	for _, it := range l {
-		gross += it.total()
-	}
-	return gross
-}
-
-// TODO: NEW
-func (l list) discount(ratio float64) {
-	type discounter interface {
-		discount(float64)
-	}
-
-	for _, it := range l {
-		dit, ok := it.(discounter)
-		if !ok {
-			continue
-		}
-
-		dit.discount(ratio)
-	}
-}

interfaces/04-interfaces/main.go

@@ -1,35 +0,0 @@
-// 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 (
-		minecraft = game{title: "minecraft", price: 20}
-		tetris    = game{title: "tetris", price: 5}
-		mobydick  = book{title: "moby dick", price: 10}
-	)
-
-	var my list
-	// my.list() // nil receiver is a valid value
-
-	// + 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()
-}