Abstract Factory Design Pattern in PHP

Back to Abstract Factory description

In the Abstract Factory Pattern, an abstract factory defines what objects the non-abstract or concrete factory will need to be able to create.

The concrete factory must create the correct objects for it's context, insuring that all objects created by the concrete factory have been chosen to be able to work correctly for a given circumstance.

In this example we have an abstract factory, AbstractBookFactory, that specifies two classes, AbstractPHPBook and AbstractMySQLBook, which will need to be created by the concrete factory.

The concrete class OReillyBookfactory extends AbstractBookFactory, and can create the OReillyMySQLBook and OReillyPHPBook classes, which are the correct classes for the context of OReilly.

<?php

/*
 * BookFactory classes
 */
abstract class AbstractBookFactory {
    abstract function makePHPBook();
    abstract function makeMySQLBook();
}

class OReillyBookFactory extends AbstractBookFactory {
    private $context = "OReilly";
    function makePHPBook() {
        return new OReillyPHPBook;
    }
    function makeMySQLBook() {
        return new OReillyMySQLBook;
    }
}

class SamsBookFactory extends AbstractBookFactory {
    private $context = "Sams";
    function makePHPBook() {
        return new SamsPHPBook;
    }
    function makeMySQLBook() {
        return new SamsMySQLBook;
    }
}

/*
 *   Book classes
 */
abstract class AbstractBook {
    abstract function getAuthor();
    abstract function getTitle();
}

abstract class AbstractMySQLBook extends AbstractBook {
    private $subject = "MySQL";
}

class OReillyMySQLBook extends AbstractMySQLBook {
    private $author;
    private $title;
    function __construct() {
        $this->author = 'George Reese, Randy Jay Yarger, and Tim King';
        $this->title = 'Managing and Using MySQL';
    }
    function getAuthor() {
        return $this->author;
    }
    function getTitle() {
        return $this->title;
    }
}

class SamsMySQLBook extends AbstractMySQLBook {
    private $author;
    private $title;
    function __construct() {
        $this->author = 'Paul Dubois';
        $this->title = 'MySQL, 3rd Edition';
    }
    function getAuthor() {
        return $this->author;
    }
    function getTitle() {
        return $this->title;
    }
}

abstract class AbstractPHPBook extends AbstractBook {
    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;
    }
}

/*
 *   Initialization
 */

  writeln('BEGIN TESTING ABSTRACT FACTORY PATTERN');
  writeln('');

  writeln('testing OReillyBookFactory');
  $bookFactoryInstance = new OReillyBookFactory;
  testConcreteFactory($bookFactoryInstance);
  writeln('');

  writeln('testing SamsBookFactory');
  $bookFactoryInstance = new SamsBookFactory;
  testConcreteFactory($bookFactoryInstance);

  writeln("END TESTING ABSTRACT FACTORY PATTERN");
  writeln('');

  function testConcreteFactory($bookFactoryInstance)
  {
      $phpBookOne = $bookFactoryInstance->makePHPBook();
      writeln('first php Author: '.$phpBookOne->getAuthor());
      writeln('first php Title: '.$phpBookOne->getTitle());

      $phpBookTwo = $bookFactoryInstance->makePHPBook();
      writeln('second php Author: '.$phpBookTwo->getAuthor());
      writeln('second php Title: '.$phpBookTwo->getTitle());

      $mySqlBook = $bookFactoryInstance->makeMySQLBook();
      writeln('MySQL Author: '.$mySqlBook->getAuthor());
      writeln('MySQL Title: '.$mySqlBook->getTitle());
  }

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

?>
BEGIN TESTING ABSTRACT FACTORY PATTERN


testing OReillyBookFactory
first php Author: Rasmus Lerdorf and Kevin Tatroe
first php Title: Programming PHP
second php Author: David Sklar and Adam Trachtenberg
second php Title: PHP Cookbook
MySQL Author: George Reese, Randy Jay Yarger, and Tim King
MySQL Title: Managing and Using MySQL


testing SamsBookFactory
first php Author: Christian Wenz
first php Title: PHP Phrasebook
second php Author: George Schlossnagle
second php Title: Advanced PHP Programming
MySQL Author: Paul Dubois
MySQL Title: MySQL, 3rd Edition


END TESTING ABSTRACT FACTORY PATTERN

Read next

Other Abstract Factory examples