Loading own classes with interfaces

[eluser]sl3dg3hamm3r[/eluser]
Hey there

I'm moving away from dealing with associative arrays without any behaviours. This results in writing proper classes. I'm now a bit stucked with loading and instantiating them. I'm aware that there is codeigniter's load_class - function. But this will fail if my class should implement an interface, and furthermore only works when the class resides in the library-folder.

As suggested here, I could implement the __autoload - interceptor into the config-file. This does it actually, but I wanted to figure out if there might be some other ways?

Where do you keep actually your classes which are rather data-providers than functional libraries? E.g. an order-class...

sl3dg3