php之Constructor Prototype Pattern 原型模式详解

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, &#39;user&#39;)
  }
  public function getUsers() {
    $rows = array();
    foreach ($this->dbAdapter->fetchAllFromTable(&#39;user&#39;) 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