Move constructors and inheritance

Question

I am trying to understand the way move constructors and assignment ops work in C++11 but I\'m having problems with delegating to parent classes.

The code:

Answer 1

You're only ever calling your base class's stuff with lvalues:

void foo(int&){}  // A
void foo(int&&){} // B

void example(int&& x)
{
    // while the caller had to use an rvalue expression to pass a value for x,
    // since x now has a name in here it's an lvalue:
    foo(x); // calls variant A
}

example(std::move(myinteger)); // rvalue for us, lvalue for example

That is, you need:

T(T&& o):
T0(std::move(o)) // rvalue derived converts to rvalue base
{
    puts("move");
}

And:

T& operator=(T&& o)
{
    puts("move assign");

    T0::operator=(std::move(o)));

    return *this;
}