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To: Marcus Boerger <helly@php.net>
CC: Derick Rethans <derick@php.net>, 
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Subject: Re: [PHP-DEV] strange autoload behavior
From: jochem@iamjochem.com (Jochem Maas)

Hi Marcus,

Marcus Boerger schreef:
> Hello Jochem,
> 
>   seems like we have quite some nice additions to the manual here in this
> thread. Now to the real issue, Exceptions don't bubble up. 

The thing is under quite a few circumstances the Exceptions do bubble up,
and there is another issue with __autoload() causing [other] errors not
to trigger the user defined error handler ... behaviour or php5.2.6 and php5.3
are the same in this regard.

I just posted another mail to internals in which I attempt to detail the
__autoload behaviour 'issues' ... it includes something that wants to be a
test suite when it grows up ... it might help someone to investage/determine
what __autoload() does/should do:

http://iamjochem.com/autoload_behaviour_tests.zip


> That is they
> are simply ignored. 

and so I thought :-) which is why some of my test's output "wtf!" :-)

as always, thanks for your feedback,
regards,
Jochem

> And once all __autoload work is done and the class
> still doesn't exist an E_ERROR is issued. The work around for cases where
> the class must not exist (e.g. when no E_ERROR is needed would be
> collecting the exceptions. That is the base Exception class would get an
> additional property and getter:
>   private $previous_exception;
>   function public getPreviousException();
> That way we could let the exceptions bubble up (though some smaller engine
> changes are necessary).

currently you can throw an exception out of __autoload() unless __autload()
is triggered by the 'new' syntax or by a static method call (e.g. MyClass::myMethod()),
with other 'triggers' (e.g. call_user_func()) the exception comes through ...
in cases that it doesn't you can get an exception out of __autoload() via the
eval() trick [see below] ... I don't suppose there is anyway of asking the engine
which way __autoload() was triggered from inside the __autoload() code?

> 
> marcus
> 
> Thursday, July 10, 2008, 7:14:33 PM, you wrote:
> 
>> Derick Rethans schreef:
>>> On Thu, 10 Jul 2008, Gergely Hodicska wrote:
>>>
>>>>> exceptions thrown during autoload are ignored.
>>>> And one more thing, this is in the manual:
>>>> "Note: Exceptions thrown in __autoload function cannot be caught in the catch
>>>> block and results in a fatal error."
>>>>
>>>> I think your explanation makes much more clear what happens, maybe it would
>>>> worth to upgrade the manual. While the quoted text suggests that that if throw
>>>> an exception I just can't catch it and will bubble up to top level and this
>>>> cause the fatal error.
>>> You can actually catch it *in* the autoload method, it just wouldn't 
>>> bubble out of it.
> 
>> the manual could do with that tidbit, maybe also the hack for 'getting the
>> exception out' of __autoload() ...
> 
>>         function __autoload($class)
>>         {
>>                 try {
>>                         throw new Exception('foo');
>>                 } catch (Exception $e) {                                
>>                     self::handleDebug($e);
>>                 
>>                     if (!class_exists($class, false))
>>                         eval(sprintf('
>>                      class %1$s
>>                      {
>>                          public         function __construct()        {
>> throw new AL_Exception("Class %1$s not found: %2$s"); }
>>                          public         function __call($m, $a)       {
>> throw new AL_Exception("Class %1$s not found: %2$s"); }
>>                          public  static function __callStatic($m, $a) {
>> throw new AL_Exception("Class %1$s not found: %2$s"); }
>>                      }', $class, $e->__toString()));                    
>>                 }
>>         }
> 
>> which works best when __autoload() isn't triggered by class_exists("Foo", true)
> 
> 
>>> regards,
>>> Derick
>>>
> 
> 
> 
> 
> 
> Best regards,
>  Marcus
> 
>