Why is unserialize_callback_func needed when spl_autoload_register is already used?

Question

ini_set(\'unserialize_callback_func\', \'spl_autoload_call\');

spl_autoload_register(array(self::getInstance(), \'autoload\'));

Why set spl_autolo

Answer 1

unserialize() requires class definition loaded before actually unserializing data. unserialize_callback_func is called when class definition is not loaded and spl_autoload_call tries to use all autoloaders registered to load class needed for unserialize().