Question

I have Environment.h file:

#include <windows.h>
#include "interfaces.h"

#ifndef ENVIRONMENT_H
#define ENVIRONMENT_H

class Environment {};
#endif

and i have Interfaces.h file:

#ifndef INTERFACES_H
#define INTERFACES_H

class IMoving {
    public: 
        virtual void Move() = 0;          
};

#endif

in interface IMoving i would like to get an Environment class, to know how to move

class IMoving {
    public: 
        virtual void Move(Environment*) = 0;          
};

if i want to do this i need to include environment.h

#include "Environment.h"

and here i’m getting an error, becouse Environment.h – includes Interfaces.h and Interfaces.h – includes Environtment.h. So how to make it work ?

Sorry for spelling mistakes

Answer 1

For circular dependencies one can use Forward declaration(s)

In Interfaces.h just above interface definition, forward declare Environment as follows:

class Environment;

Then when you implement IMoving in a class, you will include Environment.h in its implementation (cpp) file.

You can read more about Forward declaration here.