#define PHP_INI_MH( name) int name(php_ini_entry *entry, char *new_value, uint new_value_length, void *mh_arg1, void *mh_arg2, void *mh_arg3)
The fourth parameter consists of a pointer to a change-notification handler. Whenever one of these initialization entries is changed, this handler is called. Such a handler can be declared using the PHP_INI_MH macro: