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restore_exception_handler

PHP function Edit on GitHub ✎

(PHP 5, PHP 7, PHP 8)

Restores the previously defined exception handler function

Description

restore_exception_handler(): true

Used after changing the exception handler function using set_exception_handler(), to revert to the previous exception handler (which could be the built-in or a user defined function).

Note

While an exception handler is running, no exception handler is active: as of PHP 8.3.0 the engine unsets it before invoking it, so that an exception thrown by the handler is not passed back to it.

As of PHP 8.3.5 the engine also pushes the handler it is about to invoke onto the handler stack. A restore_exception_handler() call made from within an exception handler therefore pops that entry and re-installs the handler that is currently running; a second call is needed to install the handler that was active before it.

The running handler is re-installed automatically when it returns, but only if no exception handler is active at that point: a handler that calls set_exception_handler() or restore_exception_handler() is left in charge of the handler stack itself.

Parameters Parameters

Return Values

Always

Changelog

Version	Description
8.3.5	The exception handler being invoked is now pushed onto the handler stack, so `restore_exception_handler()` called from within an exception handler re-installs the handler that is currently running; restoring the handler that was active before it now requires two calls.
8.3.0	The active exception handler is now unset while it runs.

Examples

restore_exception_handler() example

php

<?php
    function exception_handler_1(Exception $e)
    {
        echo '[' . __FUNCTION__ . '] ' . $e->getMessage();
    }

    function exception_handler_2(Exception $e)
    {
        echo '[' . __FUNCTION__ . '] ' . $e->getMessage();
    }

    set_exception_handler('exception_handler_1');
    set_exception_handler('exception_handler_2');

    restore_exception_handler();

    throw new Exception('This triggers the first exception handler...');
?>

The above example will output:

output

[exception_handler_1] This triggers the first exception handler...