David, good point about the null object there. I’ve actually written about them here before, see http://codeutopia.net/blog/2009/09/12/what-is-a-null-object-and-when-are-they-useful/

please tell me how to implement this qury in zend frame work

Quite often I’ve seen something like:

throw new Exception($errno);

which is basically the same as using a return value.

The beauty of exceptions vs. return values is that they allow you to handle the situation wherever you like, not just at the point you called the method.

I generally create classes that extend Exception habitually even if my declaration is just like this:

class SomeCustomException extends Exception{}

There’s nothing worse that code catching an exception it shouldn’t! the catch(Exception …) should be the *parachute* sitting outside the entire operation of your app - it’s a sign that something went REALLY wrong because there was an exception that wasn’t caught by anything.

So the answer to the question of whether to use exceptions or return values is: you should use both by themselves or together.

Some examples:

1. Db::connect(): returns a mysql result resource or throws AccessDeniedException, InvalidHostException or DbServerException

2. Curl::exec(): returns the result of the page execution (could be ” which == FALSE but not === FALSE), or throws CurlException which contains a curl error message and curl error number

Basically a return value should pertain to the *name* of the method - to it’s original purpose. An exception is some condition that prevented it’s original purpose from being carried out.

Good topic. I think there’s not enough discussion about PHP exception handling going on.