Detect Change in function table

Hello I'm currently working on the bbcode pecl extension. This extension provides callback facilities for handling datas. Therefore I have to get the function pointer from the function table and work with those pointers. This extension will only throw a warning when a callback can not be found but will still parse all the datas effectively bypassing the callback. But between two subsequent calls with the same ressource, some function might have been added, so is there an efficient way to detect this? Because I won't be able to reset the cached functions pointers easily on each call. I'm currently implementing a brand new algorithm for the library, so the response may change some implementation details, in advance, thanks. PS: Please CC me, I have not subscribed to the list Thanks, Xavier De Cock