假设有可能,通过引用变量函数来传递参数,而不会在 PHP中生成警告？我们不能再使用’&’运算符在函数调用中,否则我会接受(尽管这样会很容易出错,编码器应该忘记它).

这是什么启发是我发掘的旧的MysqLi包装课程(这些天,我只是使用PDO).包装器和MysqLi类之间的唯一区别是包装器抛出异常而不是返回FALSE.

class DBException extends RuntimeException {}
...
class MysqLi_throwing extends MysqLi {
    ...
    function PRepare($query) {
        $stmt = parent::prepare($query);
        if (!$stmt) {
            throw new DBException($this->error,$this->errno);
        }
        return new MysqLi_stmt_throwing($this,$query,$stmt);
    }
}
// I don't remember why I swITched From extension to composition,but
// it shouldn't matter for this question.
class MysqLi_stmt_throwing /* extends MysqLi_stmt */ {
    protected $_link,$_query,$_delegate;

    public function __construct($link,$prepared) {
        //parent::__construct($link,$query);
        $this->_link = $link;
        $this->_query = $query;
        $this->_delegate = $prepared;
    }
    function bind_param($name,&$VAR) {
        return $this->_delegate->bind_param($name,$var);
    }
    function __call($name,$args) {
        //$rslt = call_user_func_array(array($this,'parent::' . $name),$args);
        $rslt = call_user_func_array(array($this->_delegate,$name),$args);
        if (False === $rslt) {
            throw new DBException($this->_link->error,$this->errno);
        }
        return $rslt;
    }
}

困难在于在包装器上调用诸如bind_result的方法.可以明确定义恒定函数(例如bind_param),允许通过引用. bind_result,但是,需要所有参数都是通过引用.如果您在MysqLi_stmt_throwing的实例上调用bind_result,那么这些参数是通过值传递的,绑定将不会占用.

try {
    $id = Null;
    $stmt = $db->prepare('SELECT id From tbl WHERE ...');
    $stmt->execute()
    $stmt->bind_result($id);
    // $id is still null at this point
    ...
} catch (DBException $exc) {
   ...
}

由于上述课程不再使用,这个问题只是一个好奇心.封装类的替代方法是不相关的.定义一个使用Null默认值的一组参数的方法是不正确的(如果定义20个参数,但该函数是用21调用的).答案甚至不需要用MysqL_stmt_throwing的方式编写;它仅仅是提供一个具体的例子.

<?PHP

/** raise all our arguments to the power of 2 */
function pow2() {
        $args = &func_get_arg(0);

        for ($i = 0; $i< count($args); ++$i) {
            $args[$i] *= 2;
        }
}


$x = 1; $y = 2; $z = 3;
pow2(array(&$x,&$y,&$z)); // this is the important line

echo "$x,$y,$z"; // output "2,4,6"

?>