Beispiel - Factory-Methode in PHP

шаблоны проектирования, factory, method, PHP

Im Fabrikmethodenmuster definiert eine Fabrikmethode, welche Funktionen einer nicht abstrakten Betonfabrik zur Verfügung stehen sollen. Diese Funktionen müssen in der Lage sein, Objekte zu erstellen, die Erweiterungen einer bestimmten Klasse sind. Welche Unterklasse erstellt wird, hängt vom Wert des an die Funktion übergebenen Parameters ab.

In diesem Beispiel haben wir eine Factory-Methode AbstractFactoryMethod , die die Funktion makePHPBook($param) implementiert.

Die OReillyFactoryMethod-Factory der konkreten Klasse erweitert die AbstractFactoryMethod-Klasse und kann eine geeignete Erweiterung der AbstractPHPBook-Klasse für den angegebenen $param-Wert erstellen.

<?php

abstract class AbstractFactoryMethod {
    abstract function makePHPBook($param);
}

class OReillyFactoryMethod extends AbstractFactoryMethod {
    private $context = "OReilly";  
    function makePHPBook($param) {
    $book = NULL;   
        switch ($param) {
            case "us":
                $book = new OReillyPHPBook;
            break;
            case "other":
                $book = new SamsPHPBook;
            break;
            default:
                $book = new OReillyPHPBook;
            break;        
        }     
    return $book;
    }
}

class SamsFactoryMethod extends AbstractFactoryMethod {
    private $context = "Sams";
    function makePHPBook($param) {
        $book = NULL;
        switch ($param) {
            case "us":
                $book = new SamsPHPBook;
            break;      
            case "other":
                $book = new OReillyPHPBook;
            break;
            case "otherother":
                $book = new VisualQuickstartPHPBook;
            break;
            default:
                $book = new SamsPHPBook;
            break;    
        }     
        return $book;
    }
}

abstract class AbstractBook {
    abstract function getAuthor();
    abstract function getTitle();
}

abstract class AbstractPHPBook {
    private $subject = "PHP";
}

class OReillyPHPBook extends AbstractPHPBook {
    private $author;
    private $title;
    private static $oddOrEven = 'odd';
    function __construct() {
        //alternate between 2 books
        if ('odd' == self::$oddOrEven) {
            $this->author = 'Rasmus Lerdorf and Kevin Tatroe';
            $this->title  = 'Programming PHP';
            self::$oddOrEven = 'even';
        } else {
            $this->author = 'David Sklar and Adam Trachtenberg';
            $this->title  = 'PHP Cookbook'; 
            self::$oddOrEven = 'odd';
        }  
    }
    function getAuthor() {return $this->author;}
    function getTitle() {return $this->title;}
}

class SamsPHPBook extends AbstractPHPBook {
    private $author;
    private $title;
    function __construct() {
        //alternate randomly between 2 books
        mt_srand((double)microtime()*10000000);
        $rand_num = mt_rand(0,1);      

        if (1 > $rand_num) {
            $this->author = 'George Schlossnagle';
            $this->title  = 'Advanced PHP Programming';
        } else {
            $this->author = 'Christian Wenz';
            $this->title  = 'PHP Phrasebook'; 
        }  
    }
    function getAuthor() {return $this->author;}
    function getTitle() {return $this->title;}
}

class VisualQuickstartPHPBook extends AbstractPHPBook {
    private $author;
    private $title;
    function __construct() {
      $this->author = 'Larry Ullman';
      $this->title  = 'PHP for the World Wide Web';
    }
    function getAuthor() {return $this->author;}
    function getTitle() {return $this->title;}
}

  writeln('START TESTING FACTORY METHOD PATTERN');
  writeln('');

  writeln('testing OReillyFactoryMethod');
  $factoryMethodInstance = new OReillyFactoryMethod;
  testFactoryMethod($factoryMethodInstance);
  writeln('');

  writeln('testing SamsFactoryMethod');
  $factoryMethodInstance = new SamsFactoryMethod;
  testFactoryMethod($factoryMethodInstance);
  writeln('');

  writeln('END TESTING FACTORY METHOD PATTERN');
  writeln('');

  function testFactoryMethod($factoryMethodInstance) {
    $phpUs = $factoryMethodInstance->makePHPBook("us");
    writeln('us php Author: '.$phpUs->getAuthor());
    writeln('us php Title: '.$phpUs->getTitle());

    $phpUs = $factoryMethodInstance->makePHPBook("other");
    writeln('other php Author: '.$phpUs->getAuthor());
    writeln('other php Title: '.$phpUs->getTitle());

    $phpUs = $factoryMethodInstance->makePHPBook("otherother");
    writeln('otherother php Author: '.$phpUs->getAuthor());
    writeln('otherother php Title: '.$phpUs->getTitle());
  }

  function writeln($line_in) {
    echo $line_in."<br/>";
  }
?>

Fazit

START TESTING FACTORY METHOD PATTERN

testing OReillyFactoryMethod
us php Author: Rasmus Lerdorf and Kevin Tatroe
us php Title: Programming PHP
other php Author: George Schlossnagle
other php Title: Advanced PHP Programming
otherother php Author: David Sklar and Adam Trachtenberg
otherother php Title: PHP Cookbook


testing SamsFactoryMethod
us php Author: Christian Wenz
us php Title: PHP Phrasebook
other php Author: Rasmus Lerdorf and Kevin Tatroe
other php Title: Programming PHP
otherother php Author: Larry Ullman
otherother php Title: PHP for the World Wide Web


END TESTING FACTORY METHOD PATTERN