Computer Science Design Patterns/Template method
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[edit] Example using Java
/** * An abstract class that is * common to several games in * which players play against * the others, but only one is * playing at a given time. */ abstract class Game { protected int playersCount; abstract void initializeGame(); abstract void makePlay(int player); abstract boolean endOfGame(); abstract void printWinner(); /* A template method : */ final void playOneGame(int playersCount) { this.playersCount = playersCount; initializeGame(); int j = 0; while (!endOfGame()) { makePlay(j); j = (j + 1) % playersCount; } printWinner(); } } //Now we can extend this class in order //to implement actual games: class Monopoly extends Game { /* Implementation of necessary concrete methods */ void initializeGame() { // Initialize money } void makePlay(int player) { // Process one turn of player } boolean endOfGame() { // Return true if game is over // according to Monopoly rules } void printWinner() { // Display who won } /* Specific declarations for the Monopoly game. */ // ... } class Chess extends Game { /* Implementation of necessary concrete methods */ void initializeGame() { // Put the pieces on the board } void makePlay(int player) { // Process a turn for the player } boolean endOfGame() { // Return true if in Checkmate or // Stalemate has been reached } void printWinner() { // Display the winning player } /* Specific declarations for the chess game. */ // ... }
[edit] Example using C#
using System; class MainApp { static void Main() { AbstractClass c; c = new ConcreteClassA(); c.TemplateMethod(); c = new ConcreteClassB(); c.TemplateMethod(); // Wait for user Console.Read(); } } // "AbstractClass" abstract class AbstractClass { public abstract void PrimitiveOperation1(); public abstract void PrimitiveOperation2(); // The "Template method" public void TemplateMethod() { PrimitiveOperation1(); PrimitiveOperation2(); Console.WriteLine(""); } } // "ConcreteClass" class ConcreteClassA : AbstractClass { public override void PrimitiveOperation1() { Console.WriteLine("ConcreteClassA.PrimitiveOperation1()"); } public override void PrimitiveOperation2() { Console.WriteLine("ConcreteClassA.PrimitiveOperation2()"); } } class ConcreteClassB : AbstractClass { public override void PrimitiveOperation1() { Console.WriteLine("ConcreteClassB.PrimitiveOperation1()"); } public override void PrimitiveOperation2() { Console.WriteLine("ConcreteClassB.PrimitiveOperation2()"); } }