<?php
/*
*
* @Author: Zuhair Mirza
* @Implementation Of Strategy Design Pattern in PHP (Practical Example)
* @Date : 12-June-2015
* @Defination : In computer programming, the strategy pattern (also known as the policy pattern) is a
* software design pattern that enables an algorithm's behavior to be selected at runtime. The strategy pattern
* defines a family of algorithms,
* encapsulates each algorithm, and
* makes the algorithms interchangeable within that family.
*
* In the Strategy Pattern a context will choose the appropriate concrete extension of a class interface.
*
* In this example, the StrategyContext class will set a strategy of StrategyCaps,
* StrategyExclaim, or StrategyStars depending on a paramter StrategyContext receives
* at instantiation. When the showName() method is called in StrategyContext it will call
* the showName() method in the Strategy that it set.
*
*/
class StrategyContext {
private $strategy = NULL;
// list is not instantiated at construct time
public function __construct($strategy_ind_id) {
switch ($strategy_ind_id) {
case "C":
$this->strategy = new StrategyCaps();
break;
case "E":
$this->strategy = new StrategyExclaim();
break;
case "S":
$this->strategy = new StrategyStars();
break;
}
}
public function showBookTitle($book) {
return $this->strategy->showTitle($book);
}
}
interface StrategyInterface {
public function showTitle($book_in);
}
class StrategyCaps implements StrategyInterface {
public function showTitle($book_in) {
$title = $book_in->getTitle();
$this->titleCount++;
return strtoupper ($title);
}
}
class StrategyExclaim implements StrategyInterface {
public function showTitle($book_in) {
$title = $book_in->getTitle();
$this->titleCount++;
return Str_replace(' ','!',$title);
}
}
class StrategyStars implements StrategyInterface {
public function showTitle($book_in) {
$title = $book_in->getTitle();
$this->titleCount++;
return Str_replace(' ','*',$title);
}
}
class Book {
private $author;
private $title;
function __construct($title_in, $author_in) {
$this->author = $author_in;
$this->title = $title_in;
}
function getAuthor() {
return $this->author;
}
function getTitle() {
return $this->title;
}
function getAuthorAndTitle() {
return $this->getTitle() . ' by ' . $this->getAuthor();
}
}
writeln('BEGIN TESTING STRATEGY PATTERN');
writeln('');
$book = new Book('Strategy Design Patern for PHP','Zuhair Mirza');
$strategyContextC = new StrategyContext('C');
$strategyContextE = new StrategyContext('E');
$strategyContextS = new StrategyContext('S');
writeln('Sample 1 ---> show name context C');
writeln($strategyContextC->showBookTitle($book));
writeln('');
writeln('Sample 2 ---> show name context E');
writeln($strategyContextE->showBookTitle($book));
writeln('');
writeln('Sample 3 ---> show name context S');
writeln($strategyContextS->showBookTitle($book));
writeln('');
writeln('END TESTING STRATEGY PATTERN');
function writeln($line_in) {
echo $line_in."<br/>";
}