public function __construct($sClass, $sClassAlias = null)
 {
     parent::__construct();
     if (is_null($sClassAlias)) {
         $sClassAlias = $sClass;
     }
     if (!is_string($sClass)) {
         throw new Exception('DBObjectSearch::__construct called with a non-string parameter: $sClass = ' . print_r($sClass, true));
     }
     if (!MetaModel::IsValidClass($sClass)) {
         throw new Exception('DBObjectSearch::__construct called for an invalid class: "' . $sClass . '"');
     }
     $this->m_aSelectedClasses = array($sClassAlias => $sClass);
     $this->m_aClasses = array($sClassAlias => $sClass);
     $this->m_oSearchCondition = new TrueExpression();
     $this->m_aParams = array();
     $this->m_aFullText = array();
     $this->m_aPointingTo = array();
     $this->m_aReferencedBy = array();
 }