Re: My Experience with PHP5 Error Handling (and possible solutions)

Davey wrote:

Dear PEARs, please don't take my ranting and raving about error handling as me just being crazy, I want to tell you about my experiences with PHP 5 with regards to using PEAR packages meant for PHP 4 as well as wanting to use exceptions. I am (and have been for about 5 months) writing a development framework, and whilst doing so I have been keenly aware that most likely, it won't be just me using it - I've been using the PEAR packaging system, and the same category system, this means anybody who has used PEAR will know how to use my framework. However, because its PHP 5 code and I wanted to use all the new PHP 5 goodies, I started using exceptions for the framework code... The framework is called Cerebral Cortex, and I use a Crtx_ prefix to all packages and therefore class names. First of all, I had the bright idea of just throwing PEAR_Error's as exceptions... to do this, I needed to take the PEAR_Error information and create a new Crtx_Exception with it. *bzzt* didn't work well, it ended up with a mess of code just to re-package an error. Next, I thought about using PEAR_ErrorStack, but instead of using ErrorStack to output the exceptions, I wanted to catch the exceptions and add them to the stack (that way, I could do some recovery and maybe not need to add them to the stack). To this end, I wrote a wrapper around PEAR_ErrorStack which would take the exception and add it to the appropriate package stack. This however, doesn't really work too well, mostly because my code was broken and I didn't want to keep repeating: try { } catch (Crtx_Exception $e) {

    $stack = Crtx_ErrorStack::createStack($e->package);
    $stack->push($e);

} Furthermore, PEAR_Errors are left out to dry... My latest attempt, which I am thinking through right now, is to write a handler for PEAR_Error which will throw them as exceptions, and a set_exception_handler() which will catch all *uncaught* exceptions and add them to the stack. This means that I can just forget about try...catch if I know I can't recover, or if its not fatal (yes, I use exceptions for any error where the flow needs to be interuptted). For warnings and notices, I just place those directly onto the stack. Furthermore, I have a special stack "user" which will have errors like "You need to fill in this form field" (i.e. user friendly notices for output to users) which the developer can choose to use, or to ignore. This is *the* best solution I can come up with, as it allows the user to just do their own set_exception_handler() to override it. I think if perhaps we come up with a solution that does the following, we can use exceptions in PHP5 and PEAR_ErrorStack in PHP4... We could do the following: 1) On PHP 4, it will use PEAR_Error with a callback to add it to the ErrorStack by default 2) On PHP 5, we can use set_exception_handler() to have a "callback" that places them on the ErrorStack by default We then do something like this: $error = PEAR_Error::raiseError(''); - This will on PHP5, throw an error (which, if not caught will be just added to the stack) and return null, on PHP4 it will return a PEAR_Error (which is also added to the stack) same as now... On PHP5 *only* packages, we can use PEAR_Exception, which will have the same effect... except it won't use PEAR_Error What do you people think? I think that if we have a slimmed down PEAR_ErrorStack (I'm thinking perhaps, make it entirely static, and not do anything with PEAR_Error/Exceptions) it will work great... This way, when mixing PHP5 and PHP4, you can just let things go and use the ErrorStack (which will work in scripts across PHP4 and PHP5), or you can use a combination of the current PEAR_Error stuff and try...catch, or a combination of PEAR_ErrorStack and try...catch or all three together (eugh). This is the best solution for PEAR that I can come up with. - Davey

That last paragraph is incorrect, you end up with these solutions: PHP4: * Use PEAR_Error *or* PEAR_ErrorStack * Use PEAR_Error and PEAR_ErrorStack (choose as you go along, messy though) PHP4 and PHP5: * Use PEAR_ErrorStack ONLY PHP5: * Use try...catch *or* PEAR_ErrorStack * Use try...catch and PEAR_ErrorStack (choose as you go along, again, messy) Hope that clarifies things :) - Davey