How do you cast away const'ness when the function takes a reference to the object (and access non-const methods)?

Question

I have a back up copy of data that I would like to protect so I made it const. I need to violate that constness on two occassions, once to store vi

Answer 1

There is a little trick I learned looking at Qt's internals:

MyClass:circunventConst() const
{
    MyClass* that = const_cast(this);
    that->myProtectedVariable = value;
}