How can I make classes defined in headers work as if they were private in a class?

[AI_Messiah]

So I am working on something that is open sourced so I don't want things to be completely hidden. I just want to have one class to be the interface to my framework and just not have things to be mentioned when they don't have to be.

[ChrisW67]

I think you will have to explain or provide an example of the type of problem you are trying to solve.

You might be thinking of something as simple as forward declaration of classes, or more complex like the PIMPL idiom (see this and this) that Qt makes heavy internal use of.