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, $query, $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.