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In software engineering, the template method pattern is a design pattern.
A template method defines the skeleton of an algorithm in terms of abstract operations which subclasses override to provide concrete behavior.
First a class is created that provides the basic steps of an algorithm by using abstract methods. Latter on, subclasses change the abstract methods to implement real actions. Thus general algorithm is saved in one place but the concrete steps may be changed by the subclasses.
Example in 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{
private 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 existing games:
class Monopoly extends Game{ /* Implementation of necessary concrete methods */ void initializeGame(){ // ... } void makePlay(int player){ // ... } boolean endOfGame(){ // ... } void printWinner(){ // ... } /* Specific declarations for the Monopoly game. */ // ... }
class Chess extends Game{ /* Implementation of necessary concrete methods */ void initializeGame(){ // ... } void makePlay(int player){ // ... } boolean endOfGame(){ // ... } void printWinner(){ // ... } /* Specific declarations for the Chess game. */ // ... }