datamapper refactoring

<?php
abstract class Vpfw_DataMapper_Abstract {
  protected $dataObjectHolders;
  protected $database;
  protected $tableInformation;

  public function __construct(Vpfw_DataBase_Interface $database, Vpfw_Config_TableInformation $tableInformation) {
    $this->database = $database;
    $this->tableInformation = $tableInformation;
    $this->initializeDataObjectHolders();
  }

  protected function initializeDataObjectHolders() {
    $this->dataObjectHolders = array();
    $this->dataObjectHolders['persistent'] = new Vpfw_DataObject_Holder();
    $this->dataObjectHolders['new'] = new Vpfw_DataObject_Holder();
  }
  
  protected function getPersistentDataObjectHolder() {
    return $this->dataObjectHolders['persistent'];
  }
  
  protected function getNewDataObjectHolder() {
    return $this->dataObjectHolders['new'];
  }
}

class Vpfw_Config_TableInformation {
  protected $columns;
  protected $tableName;
  
  public function __construct(array $informations) {
    if (!array_keys_exists(array('name', 'columns'), $informations)) {
      Vpfw_Exception_Critical('Faulty DataMapper configuration');
    }
    $this->tableName = $informations['name'];
    
    if (!is_array($informations['columns'])) {
      Vpfw_Exception_Critical('Faulty DataMapper configuration, columns has to be an array');
    } else {
      foreach ($informations['columns'] as $column) {
	$this->columns[] = new Vpfw_Config_TableColumnInformation($column);
      }
    }
  }
  
  public function getColumns() {
    return $this->columns;
  }
  
  public function getName() {
    return $this->tableName;
  }
}

class Vpfw_Config_TableColumnInformation {
  protected $name;
  protected $type;
  protected $length;
  protected $required;
  
  public function __construct(array $informations) {
    if (!array_key_exists('name', $informations)) {
      $this->missingInformation('name');
    } else {
      $this->name = $informations['name'];
    }
    
    if (!array_key_exists('type', $informations)) {
      $this->missingInformation('type');
    } else {
      $this->type = $informations['type'];
    }
    
    if (array_key_exists('length', $informations)) {
      $this->length = $informations['length'];
    }
    
    if (array_key_exists('required', $informations)) {
      if (!is_bool($informations['required'])) {
	throw new Vpfw_Exception_Logical('Expected a boolean value for the required field in table information');
      }
      $this->required = $informations['required'];
    } else {
      $this->required = true;
    }
  }
  
  public function getName() {
    return $this->name;
  }
  
  public function getType() {
    return $this->type;
  }
  
  public function getLength() {
    return $this->length;
  }
  
  public function isRequired() {
    return $this->required;
  }
}