Why D const is annoying

[Mehrdad]

> When you're making the object 'const', you're not making the assumption 
> that no one who derives from this class need mutable state.
> What you're doing is asserting that bits belonging to this object needs to 
> be 'const' to preserve sequential consistency across threads or for other 
> reasons.

Bits belonging to *this* object? I thought const was transitive...

> If the derived class casts away const, it breaks that contract.

So you're saying the same thing: Derived classes CANNOT have mutable 
state...