Re: [PHP-DEV] autoloading and undefined class constants
On Sun, Jul 5, 2009 at 10:21 PM, Ben Bidner b...@vuetec.com wrote: per the manual, exceptions thrown in an autoload method are swallowed, and an E_ERROR is triggered by php. http://us2.php.net/manual/en/language.oop5.autoload.php I have read that note before, and wondered exactly what it was referring to since you can throw exceptions within an autoloader and catch them (or have your exception handler do whatever it needs to do with them). ?php function autoloader($className) { echo autoloading . PHP_EOL; throw new Exception(Fail); } spl_autoload_register(autoloader); try { // Exception $obj = new NonExistentClass; } catch(Exception $e) { echo caught . PHP_EOL; } try { // Exception $const = constant(NonExistentClass::NON_EXISTENT_CONSTANT); } catch(Exception $e) { echo caught . PHP_EOL; } try { // Fatal error $const = NonExistentClass::NON_EXISTENT_CONSTANT; } catch(Exception $e) { echo never happens . PHP_EOL; } ? Will output: autoloading caught autoloading caught autoloading PHP Fatal error: Undefined class constant on both my systems (mentioned in reply to rob) the script fatals after the first autoloading, just like the manual says.. nat...@trident2:~$ php testcode.php autoloading Fatal error: Class 'NonExistentClass' not found in /home/nathan/testcode.php on line 41 -nathan
Re: [PHP-DEV] autoloading and undefined class constants
On Mon, Jul 6, 2009 at 6:49 AM, Ben Bidnerb...@vuetec.com wrote: ?php function autoloader($className) { throw new Exception(Fail); } spl_autoload_register(autoloader); The whole point of spl_autoload_register() is to allow programmers to have several independent autoloaders. So, it is a bad practice to throw exception from autoload — doing so, you forbid system to try the next autoloader. Good practice is: if you can't load class from autoloader — just silently return from it -- Alexey Zakhlestin http://www.milkfarmsoft.com/ -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
[PHP-DEV] autoloading and undefined class constants
Hi folks, Just looking for a quick clarification on how class constant look ups are performed internally under circumstances when an autoload function is also called. Consider the following example: ?php function autoloader($className) { throw new Exception(Fail); } spl_autoload_register(autoloader); ? ?php // Exception $obj = new NonExistantClass; ? ?php // Fatal error $const = NonExistantClass::NON_EXISTANT_CONSTANT; ? I would have assumed that since the autoloader threw an exception while attempting to load the non existant class, that internally, there would be no attempt to access the non existant constant (since surely that comes after the exception was thrown???) and we would get the Exception, rather than a Fatal error. Intended or a design error? Ben Bidner +61.7.3161.2000 (office) | +61.7.3009.0651 (fax) | +61.4.3201.5362 (mobile) http://www.vuetec.com/ -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP-DEV] autoloading and undefined class constants
On Sun, Jul 5, 2009 at 8:49 PM, Ben Bidner b...@vuetec.com wrote: Hi folks, Just looking for a quick clarification on how class constant look ups are performed internally under circumstances when an autoload function is also called. Consider the following example: ?php function autoloader($className) { throw new Exception(Fail); } spl_autoload_register(autoloader); ? ?php // Exception $obj = new NonExistantClass; ? ?php // Fatal error $const = NonExistantClass::NON_EXISTANT_CONSTANT; ? I would have assumed that since the autoloader threw an exception while attempting to load the non existant class, that internally, there would be no attempt to access the non existant constant (since surely that comes after the exception was thrown???) and we would get the Exception, rather than a Fatal error. Intended or a design error? per the manual, exceptions thrown in an autoload method are swallowed, and an E_ERROR is triggered by php. http://us2.php.net/manual/en/language.oop5.autoload.php personally, i dont know why it works this way.. even if you register an error handler, you cant handle it from user-space, b/c set_error_handler() only lets you handle E_USER_ERROR.. there are 2 issues this presents, 1. if your autoloading logic creates a message that it would pass through to higher level code, via exceptions or errors, they are swallowed, so you dont know what went wrong. 2. if you call die() you can log the message, however youll not be able to leverage standard error handling code here, at least not via a thrown exception or triggered error the only solution ive found is to invoke the standard error handling code directly from the autoloading logic. imo, this defeats the purpose of the loose coupling errors and exceptions provide. one of the reasons its really painful is because the autoloader is startup code.., which means you cant leverage it to load its dependecies, which means your error logging code cant leverage the autoloading logic iff the autoloading logic has to call the error handling logic directly:( when i say 'standard error handling logic' i mean like loading up a static html page, or similar. i think, since failures in autoload result in an E_ERROR, it would at least make sense to allow user-space to trigger E_USER_ERROR, which PHP could allow to pass through the autoload method untouched. i think this is reasonable, b/c E_USER_ERROR still interrupts program execution, and then userspace could leverage the same error handling code it does for everything else when problems occur with autoloading. id seen some posts on php.net about using output buffering to be able to trap E_ERROR but then came to discover that output buffering has been disabled on the cli since like 4.3.5, so the example code like, ?php ob_start(); call_fake_function(); ? would blow up w/ a fatal on all my installations. id post on php-general about it, but im more curious to see what internals folks think about it. -nathan
RE: [PHP-DEV] autoloading and undefined class constants
per the manual, exceptions thrown in an autoload method are swallowed, and an E_ERROR is triggered by php. http://us2.php.net/manual/en/language.oop5.autoload.php I have read that note before, and wondered exactly what it was referring to since you can throw exceptions within an autoloader and catch them (or have your exception handler do whatever it needs to do with them). ?php function autoloader($className) { echo autoloading . PHP_EOL; throw new Exception(Fail); } spl_autoload_register(autoloader); try { // Exception $obj = new NonExistentClass; } catch(Exception $e) { echo caught . PHP_EOL; } try { // Exception $const = constant(NonExistentClass::NON_EXISTENT_CONSTANT); } catch(Exception $e) { echo caught . PHP_EOL; } try { // Fatal error $const = NonExistentClass::NON_EXISTENT_CONSTANT; } catch(Exception $e) { echo never happens . PHP_EOL; } ? Will output: autoloading caught autoloading caught autoloading PHP Fatal error: Undefined class constant I would expect accessing a constant directly to behave as constant() does at the moment and I would expect constant() to behave as the manual says it does (and return NULL for non existent class constants instead of throwing E_ERRORs). Ben Bidner +61.7.3161.2000 (office) | +61.7.3009.0651 (fax) | +61.4.3201.5362 (mobile) http://www.vuetec.com/ -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php