为什么不'；新操作员创建链结构

假设GeneralNews()返回this，CreateInstance()返回this，前两个方法有效，但最后一个方法失败。

我不明白为什么？

$objGeneralNews = new GeneralNews();  
$arrDataList = $objGeneralNews->SetWhere('news01date="2011-01-01"')->GetFrontList();
var_dump( $arrDataList ); //This method works
$arrDataList = GeneralNews::CreateInstance()->SetWhere('news01date="2011-01-01"')->GetFrontList();
var_dump( $arrDataList ); //This method works  
$arrDataList = (new GeneralNews())->SetWhere('news01date="2011-01-01"')->GetFrontList();
var_dump( $arrDataList ); //This method doesn't works  

分类代码通用新闻：

class GeneralNews {         
    public function GeneralNews(){
        return this;
    } 
    public static function CreateInstance(){  
        $strClassName = 'GeneralNews';   
        return new $strClassName;  
    }
}