PHP extensions dependencies

Hello everybody! I'm writing a PHP extension and I've got a problem: is there a way to include another module's functions in my own? Actually, I want to use some internals functions of a module and access to these globals (xdebug) in my own. For instance, if I want to use the "xdebug_error_type" function, which is in the "xdebug_var.c" file, can I just include the "xdebug_var.h" (which I need to copy in my own module because it isn't saved when installing "php-dev/xdebug" on Gentoo) and them call the function? Is there another way? Is it possible? Thanks you very much in advance! Regards, Samuel ROZE.