http://pointersgonewild.wordpress.com/2014/07/11/the-constness-problem/
I can relate to this. I don't use classes much in D, but I find it frustrating that you need to reach to std.typecons.Rebindable for what I would consider to be a more common usage of const with classes.
I really feel that a mutable reference to a const object should be expressible in the core language.
