析构函数中异常处理

PHP代码：

<?php
class Foo
{
    function __destruct() {
        throw new Exception('abc');
    }

}

$foo = new Foo();
?>

PHP5.3.6版本的执行结果是：

Fatal error: Exception thrown without a stack frame in Unknown on line 0

而PHP5.3.8的结果则是：

Fatal error: Uncaught exception ‘Exception’ with message ‘abc’ in C:\Users\hdj\Desktop\demo.php:5
Stack trace:
#0 [internal function]: Foo->__destruct()
#1 {main}
thrown in C:\Users\hdj\Desktop\demo.php on line 5

PHP手册里的解析是：

试图在析构函数中抛出一个异常会导致致命错误。

PHP5.3.8官方的更新日志：

Fixed bug #43175 (__destruct() throwing an exception with __call() causes segfault). (Dmitry)

所了解，有这么一种说法：PHP析构函数里抛出异常时，如果你注册了自己的异常处理函数，并且再次抛出异常就会出错。

PHP代码：

<?php
class MyException extends Exception
{
    //
}

function throw_exception($msg='Unknown exception', $type='MyException', $code=0){
    if(class_exists($type))
        throw new $type($msg, $code);
    else
        die($msg);
}

class Foo
{
    function __destruct() {
        // throw new Exception('abc');
        throw_exception('abc');
    }
}

$foo = new Foo();
?>

PHP5.3.8环境下执行结果：

Fatal error: Uncaught exception ‘MyException’ with message ‘abc’ in C:\Users\hdj\Desktop\demo.php:9
Stack trace:
#0 C:\Users\hdj\Desktop\demo.php(18): throw_exception(‘abc’)
#1 [internal function]: Foo->__destruct()
#2 {main}
thrown in C:\Users\hdj\Desktop\demo.php on line 9