Re: Best practice concerning Exceptions

On Thu, 2010-03-11 at 10:51 +1030, Daniel O'Connor wrote: > On Thu, Mar 11, 2010 at 1:07 AM, Auke van Slooten <auke@muze.nl> wrote: > > > Hi, > > > > I've found the XML_RPC2 package (only after writing my own version of it > > ofcourse :( ..) and noticed that it declares quite a number of different > > exception classes. I've read the 'Error Handling Guidelines for PHP5 > > Packages' but couldn't find any information on when to use a new Exception > > class and when simply to use a new code and message. > > > > What is considered good practice for PHP5 exceptions? My own code uses just > > two exception classes, with about 8 different codes and messages. It seems > > the XML_RPC2 package throws a specific exception class for each error, > > skipping error codes. > > > > > > I find that most people (myself included) just rely on a general category of > exception; and rarely if ever make use of exception codes. > > IE; I'd do: > > class Foo { > public function bar($path) { > // Checking to ensure things are 'valid' or 'expected' -> > InvalidArgumentExceptions > if (!file_exists($path)) { > throw new InvalidArgumentException("Path must exist"); > } > > // Doing the actual business logic; and unexpected things happen > $content = file_get_contents($path); > if (empty($content)) { > throw new InvalidDataException("It looks like the supplied file > is empty"); > } > } > } > > > rather than > > throw new FooException("Path must exist", Foo::INVALID_ARGUMENT); > throw new FooException("It looks like the supplied file is empty", > Foo::INVALID_DATA); Hi Auke, I typically create a new exception class for each category of error and then use codes to distinguish specific errors in those categories. I like to use and extend the built-in SPL exceptions where applicable. For example, in a web service API wrapper, I might have: * Foo_Exception * Foo_HttpException * Foo_AuthenticationException Then I might have more specific exceptions for specific circumstances. When deciding whether or not to create a new exception class, I think about how it would be to write error handling code for the error in question, and think about how the error should be logged. Hope this helps, Mike