Adding new listings for chapter 10.

chapter10/listing01/listing01.go

@@ -0,0 +1,97 @@
+// Sample program demonstrating struct composition.
+package main
+
+import "fmt"
+
+// Board represents a surface we can work on.
+type Board struct {
+ NailsNeeded int
+ NailsDriven int
+}
+
+// =============================================================================
+
+// Mallet is a tool that pounds in nails.
+type Mallet struct{}
+
+// DriveNail pounds a nail into the specified board.
+func (Mallet) DriveNail(nailSupply *int, b *Board) {
+ *nailSupply--
+ b.NailsDriven++
+ fmt.Println("Mallet: pounded nail into the board.")
+}
+
+// Crowbar is a tool that removes nails.
+type Crowbar struct{}
+
+// PullNail yanks a nail out of the specified board.
+func (Crowbar) PullNail(nailSupply *int, b *Board) {
+ b.NailsDriven--
+ *nailSupply++
+ fmt.Println("Crowbar: yanked nail out of the board.")
+}
+
+// =============================================================================
+
+// Toolbox can contains a Mallet and a Crowbar.
+type Toolbox struct {
+ Mallet
+ Crowbar
+
+ nails int
+}
+
+// =============================================================================
+
+// Contractor carries out the task of securing boards.
+type Contractor struct{}
+
+// Fasten will drive nails into a board.
+func (Contractor) Fasten(m Mallet, nailSupply *int, b *Board) {
+ for b.NailsDriven < b.NailsNeeded {
+ m.DriveNail(nailSupply, b)
+ }
+}
+
+// Unfasten will remove nails from a board.
+func (Contractor) Unfasten(cb Crowbar, nailSupply *int, b *Board) {
+ for b.NailsDriven > b.NailsNeeded {
+ cb.PullNail(nailSupply, b)
+ }
+}
+
+// ProcessBoards works against boards.
+func (c Contractor) ProcessBoards(tb *Toolbox, nailSupply *int, boards []Board) {
+ for i := range boards {
+ b := &boards[i]
+
+ fmt.Printf("Contractor: examining board #%d: %+v\n", i+1, b)
+
+ switch {
+ case b.NailsDriven < b.NailsNeeded:
+ c.Fasten(tb.Mallet, nailSupply, b)
+
+ case b.NailsDriven > b.NailsNeeded:
+ c.Unfasten(tb.Crowbar, nailSupply, b)
+ }
+ }
+}
+
+// =============================================================================
+
+// main is the entry point for the application.
+func main() {
+ boards := []Board{
+ {NailsDriven: 3},
+ {NailsNeeded: 2},
+ }
+
+ tb := Toolbox{
+ Mallet: Mallet{},
+ Crowbar: Crowbar{},
+ nails: 10,
+ }
+
+ var c Contractor
+ c.ProcessBoards(&tb, &tb.nails, boards)
+}

chapter10/listing02/listing02.go

@@ -0,0 +1,109 @@
+// Sample program demonstrating decoupling with interfaces.
+package main
+
+import "fmt"
+
+// Board represents a surface we can work on.
+type Board struct {
+ NailsNeeded int
+ NailsDriven int
+}
+
+// =============================================================================
+
+// NailDriver represents behavior to drive nails into a board.
+type NailDriver interface {
+ DriveNail(nailSupply *int, b *Board)
+}
+
+// NailPuller represents behavior to remove nails into a board.
+type NailPuller interface {
+ PullNail(nailSupply *int, b *Board)
+}
+
+// =============================================================================
+
+// Mallet is a tool that pounds in nails.
+type Mallet struct{}
+
+// DriveNail pounds a nail into the specified board.
+func (Mallet) DriveNail(nailSupply *int, b *Board) {
+ *nailSupply--
+ b.NailsDriven++
+ fmt.Println("Mallet: pounded nail into the board.")
+}
+
+// Crowbar is a tool that removes nails.
+type Crowbar struct{}
+
+// PullNail yanks a nail out of the specified board.
+func (Crowbar) PullNail(nailSupply *int, b *Board) {
+ b.NailsDriven--
+ *nailSupply++
+ fmt.Println("Crowbar: yanked nail out of the board.")
+}
+
+// =============================================================================
+
+// Toolbox can contains a Mallet and a Crowbar.
+type Toolbox struct {
+ Mallet
+ Crowbar
+
+ nails int
+}
+
+// =============================================================================
+
+// Contractor carries out the task of securing boards.
+type Contractor struct{}
+
+// Fasten will drive nails into a board.
+func (Contractor) Fasten(d NailDriver, nailSupply *int, b *Board) {
+ for b.NailsDriven < b.NailsNeeded {
+ d.DriveNail(nailSupply, b)
+ }
+}
+
+// Unfasten will remove nails from a board.
+func (Contractor) Unfasten(p NailPuller, nailSupply *int, b *Board) {
+ for b.NailsDriven > b.NailsNeeded {
+ p.PullNail(nailSupply, b)
+ }
+}
+
+// ProcessBoards works against boards.
+func (c Contractor) ProcessBoards(tb *Toolbox, nailSupply *int, boards []Board) {
+ for i := range boards {
+ b := &boards[i]
+
+ fmt.Printf("Contractor: examining board #%d: %+v\n", i+1, b)
+
+ switch {
+ case b.NailsDriven < b.NailsNeeded:
+ c.Fasten(tb.Mallet, nailSupply, b)
+
+ case b.NailsDriven > b.NailsNeeded:
+ c.Unfasten(tb.Crowbar, nailSupply, b)
+ }
+ }
+}
+
+// =============================================================================
+
+// main is the entry point for the application.
+func main() {
+ boards := []Board{
+ {NailsDriven: 3},
+ {NailsNeeded: 2},
+ }
+
+ tb := Toolbox{
+ Mallet: Mallet{},
+ Crowbar: Crowbar{},
+ nails: 10,
+ }
+
+ var c Contractor
+ c.ProcessBoards(&tb, &tb.nails, boards)
+}

chapter10/listing03/listing03.go

@@ -0,0 +1,115 @@
+// Sample program demonstrating interface composition.
+package main
+
+import "fmt"
+
+// Board represents a surface we can work on.
+type Board struct {
+ NailsNeeded int
+ NailsDriven int
+}
+
+// =============================================================================
+
+// NailDriver represents behavior to drive nails into a board.
+type NailDriver interface {
+ DriveNail(nailSupply *int, b *Board)
+}
+
+// NailPuller represents behavior to remove nails into a board.
+type NailPuller interface {
+ PullNail(nailSupply *int, b *Board)
+}
+
+// NailDrivePuller represents behavior to drive and remove nails into a board.
+type NailDrivePuller interface {
+ NailDriver
+ NailPuller
+}
+
+// =============================================================================
+
+// Mallet is a tool that pounds in nails.
+type Mallet struct{}
+
+// DriveNail pounds a nail into the specified board.
+func (Mallet) DriveNail(nailSupply *int, b *Board) {
+ *nailSupply--
+ b.NailsDriven++
+ fmt.Println("Mallet: pounded nail into the board.")
+}
+
+// Crowbar is a tool that removes nails.
+type Crowbar struct{}
+
+// PullNail yanks a nail out of the specified board.
+func (Crowbar) PullNail(nailSupply *int, b *Board) {
+ b.NailsDriven--
+ *nailSupply++
+ fmt.Println("Crowbar: yanked nail out of the board.")
+}
+
+// =============================================================================
+
+// Toolbox can contains a Mallet and a Crowbar.
+type Toolbox struct {
+ Mallet
+ Crowbar
+
+ nails int
+}
+
+// =============================================================================
+
+// Contractor carries out the task of securing boards.
+type Contractor struct{}
+
+// Fasten will drive nails into a board.
+func (Contractor) Fasten(d NailDriver, nailSupply *int, b *Board) {
+ for b.NailsDriven < b.NailsNeeded {
+ d.DriveNail(nailSupply, b)
+ }
+}
+
+// Unfasten will remove nails from a board.
+func (Contractor) Unfasten(p NailPuller, nailSupply *int, b *Board) {
+ for b.NailsDriven > b.NailsNeeded {
+ p.PullNail(nailSupply, b)
+ }
+}
+
+// ProcessBoards works against boards.
+func (c Contractor) ProcessBoards(dp NailDrivePuller, nailSupply *int, boards []Board) {
+ for i := range boards {
+ b := &boards[i]
+
+ fmt.Printf("Contractor: examining board #%d: %+v\n", i+1, b)
+
+ switch {
+ case b.NailsDriven < b.NailsNeeded:
+ c.Fasten(dp, nailSupply, b)
+
+ case b.NailsDriven > b.NailsNeeded:
+ c.Unfasten(dp, nailSupply, b)
+ }
+ }
+}
+
+// =============================================================================
+
+// main is the entry point for the application.
+func main() {
+ boards := []Board{
+ {NailsDriven: 3},
+ {NailsNeeded: 2},
+ }
+
+ tb := Toolbox{
+ Mallet: Mallet{},
+ Crowbar: Crowbar{},
+ nails: 10,
+ }
+
+ var c Contractor
+ c.ProcessBoards(&tb, &tb.nails, boards)
+}