`restricted` member variables

[Dom Disc]

The longer I think about it (and that's really long, because of 
this thread), the more I dislike class private.
It's a bogus concept.
It make you think you have a strong type, but you can't prevent 
others from messing it up.

Maybe in very small projects (where it makes at least a little 
bit of sense to put everything in few files) it helps you to 
avoid making stupid mistakes (like using some private field in a 
function that shouldn't use it), but if the project grows the 
code must be re-organized anyway.
So it is much better to learn to do this from the start. And 
having one class in one file provides the same "protection" from 
stupid mistakes.