Converting PHP errors into exceptions

Question

I've written error handling class which divided all errors into the normal ones (notices, warnings, ...), and the critical ones.

Now I've found out that it's a good practice to convert all errors into exceptions. It would also shorten my code.

However, I'm not sure how to handle this...

1. Are there exceptions that don't stop scripts execution, and exceptions that do? If there aren't...how to differ converted errors?
2. Converting errors into exception is done by calling set_error_handler() and throw new ErrorException() in there...What's next? set_exception_handler() is called automagically?

Answer 1

1. Caught exceptions do not stop your script, all uncaught ones do.

2. No, set_exception_handler() is not called automatically, you can do that if you like.

   The exception handler you set with set_exception_handler() gets called after an exception has gone uncaught, it is the last piece of code that gets called before the script terminates. Make sure it doesn't cause an error/exception, or it will end badly.

Answer 2

1. Are there exceptions that don't stop scripts execution, and exceptions that do? If there aren't...how to differ converted errors?

Exceptions don't stop script execution if they're caught. To recognize a converted error:

try {
    // ...
} catch (ErrorException $e) {
    // converted error (probably)
} catch (Exception $e) {
    // another kind of exception; this basically catches all
}

Or:

function handle_exception(Exception $e)
{
    if ($e instanceof ErrorException) {
        // converted error (probably)
    } else {
        // another kind of exception
    }
}
set_exception_handler('handle_exception');

Note that ErrorException can be thrown by any piece of code, but it was meant to convert regular errors in set_error_handler() registered functions only.

1. Converting errors into exception is done by calling set_error_handler() and throw new ErrorException() in there...What's next? set_exception_handler() is called automagically?

If the thrown ErrorException from your error handler function is not caught anywhere else in your code, the registered exception handler (set using set_exception_handler()) will be called.

Answer 3

Any uncaught exception will stop execution of your script.

When an exception is thrown, code following the statement will not be executed, and PHP will attempt to find the first matching catch block. If an exception is not caught, a PHP Fatal Error will be issued with an "Uncaught Exception ..." message, unless a handler has been defined with set_exception_handler().

See docs about this

As for set_exception_handler() - it is not called automatically, but it is your last resort to react to the problem that occured

Sets the default exception handler if an exception is not caught within a try/catch block. Execution will stop after the exception_handler is called.