[C++11] Explicitly delete functions

In the C++11, there is a new feature to explicitly delete functions. With this new feature, for example we can delete the copy constructor and copy-assignment operator that compiler automatically generates for us to prevent copy operation.

Before C++11

class Uncopyable {
public:
    Uncopyable() {};
private:
    Uncopyable(const Uncopyable& oth);
    Uncopyable& operator=(const Uncopyable& oth);
};

Before C++11, this code is a solution to prevent copy operation. But it still be copyable for a friend class of Uncopyable.

In C++11

class Uncopyable {
public:
    Uncopyable() {};

    Uncopyable(const Uncopyable& oth) =delete;
    Uncopyable& operator=(const Uncopyable& oth) =delete;
};

In C++11, there is a more straightforward way to implement this. The =delete marks the function to be deleted. When you do something like this

Uncopyable a, b;
b = a;

It will give you a error message at compile time.