PHP 8.5: New get_exception_handler and get_error_handler functions

PHP allows setting custom error and exception handlers which get called when an error is triggered, or an exception is uncaught. It is also possible to restore the previous exception and error handlers.

However, until PHP 8.5, there was no direct way to get the currently set error and exception handlers. PHP 8.5 adds a couple of functions -- get_error_handler and get_exception_handler that provide this functionality.

Setting Error and Exception Handlers

set_error_handler and set_exception_handler functions accept a callable parameter, that gets called when PHP emits an error or encounters an uncaught exception.

set_error_handler('my_custom_error_handler_function');
set_exception_handler('my_custom_exception_handler_function');

When setting error and exception handlers, the set_*_handler function calls return the existing error handler.

New get_error_handler function

PHP 8.5 adds a new function named get_error_handler that returns the currently active error handler:

/**
 * Returns the currently set error handler, or null if none is set.
 * @return callable|null
 */
function get_error_handler(): ?callable {}

Usage examples

If there is no error handler set, calling get_error_handler returns null:

get_error_handler(); // null

When a custom error handler is set, get_error_handler returns the set callable:

set_error_handler(fn() => null);
get_error_handler(); // object(Closure)#1 (3) {...}

New get_exception_handler function

The new get_exception_handler function in PHP 8.5 works similarly to the get_error_handler function. It returns the currently set exception handler, or null if there is no exception handler set.

/**
 * Returns the currently set exception handler, or null if none is set.
 * @return callable|null
 */
function get_exception_handler(): ?callable {}

Usage examples

If there is no exception handler set, calling get_error_handler returns null:

get_error_handler(); // null

When a custom error handler is set, get_error_handler returns the set callable:

set_error_handler(fn() => null);
get_error_handler(); // object(Closure)#1 (3) {...}

PHP Polyfill

Because set_error_handler and set_exception_handler functions return the current handlers, it is possible to trivially polyfill these functions using PHP:

/**
 * Returns the currently set error handler, or null if none is set.
 * @return callable|null
 */
function get_error_handler(): ?callable {
    $handler = set_error_handler(null);
    restore_error_handler();

    return $handler;
}

/**
 * Returns the currently set exception handler, or null if is none set.
 * @return callable|null
 */
function get_exception_handler(): ?callable {
    $handler = set_exception_handler(null);
    restore_exception_handler();

    return $handler;
}

Backward Compatibility Impact

get_error_handler and get_exception_handler are new functions introduced in PHP 8.5. Unless an existing PHP application declares identical function names in the global namespace, this change has no backward compatibility impact.

Further, it is possible to polyfill these two functions in PHP.

---

get_error_handler get_exception_handler RFC Discussion Implementation