Question

I have some class(Window) without copy constructor (it’s private). I can’t understand how to init var of this class in my own class:

class MyClass
{
   Window obj; // Hasn't copy constructor
   public:
      void init()
      {
         obj = Window(/* constructor params */); // [error]
         obj(/* constructor params */); // [error]
      }
}

Error 1: initializing argument 1 of ‘Window::Window(WindowHandle, const sf::WindowSettings&)’

Error 2: ‘NonCopyable& NonCopyable::operator=(const NonCopyable&)’ is private

But it works in this way:

Window obj(/* constructor params */);

Answer 1

Your MyClass needs a constructor to initialize the obj member.

class MyClass 
{ 
private:
    Window obj;
public: 
    MyClass() : obj(/* constructor params */) // This is an initializer list
    {}
};

If you need the init() function, and the Window object provides its own
init() function of some sort, you can do this:

class MyClass 
{ 
private:
    Window obj;
public: 
    void init() 
    { 
        obj.init(/* init params */); // Window's own init() function
    }
};

If the Window class does not have anything like an init() function, you can use the heap (not recommended unless you absolutely have to):

class MyClass 
{ 
private:
    // Alternatively, we can use a smart pointer here and avoid
    // managing memory ourselves.
    Window* obj;
public: 
    MyClass() : obj(0) {}
    ~MyClass() { uninit(); }
    void init() 
    { 
        uninit();
        obj = new Window(/* constructor params */);
    }
    void uninit()
    {
        if(obj != 0)
        {
            delete obj;
            obj = 0;
        } 
    }
};

If the Window class declares a private copy constructor and/or copy assignment operator, then you cannot assign a new Window instance to obj.