Question

When I’m writing a class (say class nocopy), is it possible to prevent the existence of the copy operator entirely? If I don’t define one, and somebody else writes something like

nocopy A;
nocopy B;
A = B;

the compiler will auto-generate a definition. If I define one myself, I will prevent the compiler from auto-generating, but the code above will still be legal.

I want the code above to be illegal, and generate a compile time error. How do I do that?

Answer 1

You just declare a copy constructor with private access specifier and not even define it.
Anyone trying to use it will get an compile error since it is declared private.

If someone uses it even indirectly, you will get a link error.

You can’t do anything more than that in C++03.

However, In C++11 you can Explicitly delete special member functions.

Eg:

struct NonCopyable {
    NonCopyable & operator=(const NonCopyable&) = delete;
    NonCopyable(const NonCopyable&) = delete;
    NonCopyable() = default;
};