Catch not working and how to unset the exception handler

问题

catch is not working because there is installed an exception handler using set_exception_handler()

I need "catch" to work, so I guess I need to unset the exception handler somehow. Things such as set_exception_handler(NULL) isn't working.

Any ideas how to unset the exception handler?

function my_exception_handler($exception) {
    error_log("caught exception: " . $exception->getMessage() );
}

set_exception_handler("my_exception_handler");

// QUESTION: how does on unset it ?
//set_exception_handler(NULL);

try {
    throw new Exception('hello world');
    error_log("should not happen");
} catch(Exception $e) {
    error_log("should happen: " . $e->getMessage());
}

Actual output:

caught exception: hello world

Desired output:

should happen: hello world

回答1:

restore_exception_handler, which is linked from the manual entry for set_exception_handler.

BTW, these exception handlers should only come into play when an exception is uncaught. A catch block should always have precedence.

---

Reading a little bit in the comments on the Exceptions page brings you to this bug and this bug. They describe exactly what you experience, Exceptions can't be caught when a custom error handler is defined.

Solution:

Fixed in 5.3 and HEAD, won't be backported to 5.2.

回答2:

The function is restore_exception_handler. However, the handler should only be called when an exception is unhandled. It does not disable catches.

来源：https://stackoverflow.com/questions/2714342/catch-not-working-and-how-to-unset-the-exception-handler