php示例详解Constructor Prototype Pattern 原型模式

public function getServiceConfig()  {    return array(      'factories' => array(        'Album/Model/AlbumTable' => function($sm) {          $tableGateway = $sm->get('AlbumTableGateway');          $table = new AlbumTable($tableGateway);          return $table;        },        'AlbumTableGateway' => function ($sm) {          $dbAdapter = $sm->get('Zend/Db/Adapter/Adapter');          $resultSetPrototype = new ResultSet();          $resultSetPrototype->setArrayObjectPrototype(new Album());//这个就是一个不变的原型          return new TableGateway('album', $dbAdapter, null, $resultSetPrototype);//传入到TableGateWay的构造函数中去        },      ),    );  }

<?php//框架中很常见的adapter类，用来适配各种数据库，封装一些基本数据库连接操作。//相当于上面代码中的adapter类class DbAdapter {  public function fetchAllFromTable($table) {    return $arrayOfData;  }}//运用prototype pattern的类，注意construct和initialize是分开的//相当于上面zend 代码里面的ResultSet类class RowGateway {  public function __construct(DbAdapter $dbAdapter, $tableName) {    $this->dbAdapter = $dbAdapter;    $this->tableName = $tableName;  }  public function initialize($data) {    $this->data = $data;  }  /**   * Both methods require access to the database adapter   * to fulfill their duties   */  public function save() {}  public function delete() {}  public function refresh() {}}//相当于上面代码中的TableGateway类，关于gateway可以具体去了解一下。class UserRepository {  public function __construct(DbAdapter $dbAdapter, RowGateway $rowGatewayPrototype = null) {    $this->dbAdapter = $dbAdapter;    $this->rowGatewayPrototype = ($rowGatewayPrototype) ? new RowGateway($this->dbAdapter, 'user')  }  public function getUsers() {    $rows = array();    foreach ($this->dbAdapter->fetchAllFromTable('user') as $rowData) {      $rows[] = $row = clone $this->rowGatewayPrototype;      $row->initialize($rowData);    }    return $rows;  }}

class ReadWriteRowGateway extends RowGateway {  public function __construct(DbAdapter $readDbAdapter, DbAdapter $writeDbAdapter, $tableName) {    $this->readDbAdapter = $readDbAdapter;    parent::__construct($writeDbAdapter, $tableName);  }  public function refresh() {    // utilize $this->readDbAdapter instead of $this->dbAdapter in RowGateway base implementation  }}// usage:$userRepository = new UserRepository(  $dbAdapter,  new ReadWriteRowGateway($readDbAdapter, $writeDbAdapter, 'user'));$users = $userRepository->getUsers();$user = $users[0]; // instance of ReadWriteRowGateway with a specific row of data from the db