Re: Questions about using exceptions

Arnold Daniels wrote: > Hi all, > > I've got two questions about using PEAR_Exceptions when building a PHP5 > Pear class: > > 1.) When extending a PHP 4 class, should I throw an exception my own > and work around the existing code? I imagine you are talking about a scenario where the old package returns an error value. Something like class OldClass { /** * @return boolean True if successfull, false otherwise */ function foo() { (...) } } And testing the return value in the new PHP5 class, like this: class NewClass extends OldClass { public function foo() { if (!parent::foo()) { throw new Exception(...); } } } To fullfill the requirements of the exception usage RFC, the PHP5 package should use only exceptions as error signaling, never error value returns. This would mean wrapping *every* old method to convert return values into exceptions. However, the RFC was written with pure PHP5 packages in mind (i.e. E_STRICT compliance), not for transitional code. For transitional code, it may be more trouble than what its worth, morphing all methods to throw exceptions, not return values. PHP4 -> PHP5 Transition was never discussed here in the list, but in my opinion, wrapping the methods is more trouble than what it's worth. The transitional code shouldn't last more than a couple of years, as packages evolve into E_STRICT PHP5. > 2.) Should I only add a @throws note in the DocBlock for exceptions > which are thrown in that particular function, or also exceptions thrown > in other functions called by this function? Documenting all exceptions is a recommendation, but not a requirement in the exceptions RFC. You should do it, as it provides a complete description of error behaviour for the method. It is not required, because it can be a lot of work, and rules should be easy to follow. Ideally, phpdoc should infer it from the code, but that would be too good to be true ;-) Cheers, Sérgio Carvalho