Securing PHP code. Need some tips

I want to encode my codes with ionCube. But I do not know exactly how to prevent users from cracking it without encoding.

So I need some tips.

My project is a 开发者_运维问答MVC.

Everything starts in index.php and it calls core.php and running goes.

How should I include files. How can I ensure that when a file is called it is the original one?

I know there is some PHP functions that print out function names, etc. I need to prevent this.

Users include index.php file from another file and try to get variables like using var_dump($_GLOBALS);

You can use the get_included_files function to see if there are other files included. But the best way is of course to trust your customers and regulate what they can and cannot do with your code through contracts.