Propagate constness to data pointed by member variables

Question

It is often quite confusing to C++ newcomers that const member functions are allowed to call non-const methods on objects referenced by the class (either by pointer or refer

Answer 1

For the record, I just found out that the Loki library does provide a const propagating pointer (ConstPropPtr). It looks just like the one in the question, except that it also deletes the wrapped pointer in its destructor, and it is used to implement a Pimpl class similar to the one proposed by @Matthieu (but not copyable).