Unique pointers with derived classes

[begha]

This may sound confusing, but here goes. So I have two inferfaces, intoLogic and intoView, both of which are abstract classes. Both of them are derived to two classes, Logic and View. Basically, I want to have the class Logic call functions from interface intoView, that View will actually execute. Then I want to have the class View call functions from interface intoLogic, that Logic will actually execute. So basically, View calls a function from intoLogic, that actual Logic will execute and then Logic calls a function from intoView, that actual View will execute. So in code, it looks something like this:

class intoLogic
{
public:
   virtual void calculate() = 0;
};

class Logic: public intoLogic
{
public:
   Logic();
   void calculate();
private:
   //A (unique) pointer of type intoView that points at View, so that I can
   //call for instance pointertoview->showResult();
};

class intoView
{
public:
   virtual void showResult() = 0;
};

class View: public intoView
{
public:
   View();
   void showResult();
private:
   //A (unique) pointer of type intoLogic that points at Logic, so that I can
   //call for instance pointertologic->calculate();
};

So how do I create the unique pointers that way? Is it overall possible to have something like

std::unique_ptr<intoView> graphics(new View);

in the private of Logic, so that I can call graphics->showResult();?

When I try implementing it like that, I get a lot of problems trying to include everything needed in the classes. So how should I solve this? I was thinking about a factory method, where I create a separate module to assign the unique pointers, but is there an easier way?

EDIT: I tried doing it with the factory method, but it will just end up with the program stuck in an infinite loop. I'm out of ideas.

[ne555]

> When I try implementing it like that, I get a lot of problems trying to include everything needed in the classes.
http://www.cplusplus.com/forum/articles/10627/
separate the declaration and definition of the member functions.
only the definition file would need to include logic


> Is it overall possible to have something like
> std::unique_ptr<intoView> graphics(new View);
> in the private of Logic, so that I can call graphics->showResult();?
¿you don't care about the state of the object?
As long as your base class destructor is virtual there would be no problem, but you could as well do

View graphics;
graphics.showResult();

> it will just end up with the program stuck in an infinite loop
I don't want to play a guessing game.
in order to find out what you did wrong we need to know what you did.

[Disch]

unique pointer implies ownership.

If a Logic owns a View... then a View can't own a Logic because you'll create a never ending chain of objects. If you want the objects to refer to each other, then you'll need a non-ownership pointer (ie: a basic pointer)

[begha]

Actually I think I have some sort of an idea what the problem is with the infinite loop.

I already have one View-object in main.cpp, since the View actually creates the UI for the program. Eventually when the View creates a pointer to intoLogic, it will create a new object of Logic. So far so good. But then the Logic needs to create a pointer pointing at the View-object, but it will actually dynamically allocate a new instance of View. So there we have an infinite loop. That new instance of View will again create a new Logic and that Logic will again create a new instance of view. I'll have to test this out in practice.

[Disch]

Yes, that is what I said. =P