Hasan Setiawan

Understanding PHP Abstract Factory

An object implementing the Abstract Factory Pattern creates Factories of a specific type which in turn are used to create concrete objects of a specific type.

The definition above may vary. The use of the Abstract Factory Pattern can differ among implementations. In many cases the AbstractFactory will create a concrete Factory and control its use internally rather than simply passing the Factory back to the client. In the examples below we assume the client simply want to get hold of the actual concrete Factory object to use themselves.

      
          /*
           * 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. "";
            }