//run.cpp
#include <iostream>

using namespace std;

int main(){
        HFact* fact;
#ifdef LINUX
        HFact* fact = new HelloLinFact;
#elif WINDOWS
        //HFact* fact = new HelloWinFact;
        cout<<"At the moment this implementation is not valid..."<<endl;
#endif

        CHello* hello = fact->getHelloNormal();
        hello->say();
        hello = fact->getHelloReversed();
        hello->say();
        hello = fact->getHelloWorld();
        hello->say();

        return 0;

}

//HFact.cpp
class HFact {
        public:
                extern virtual CHello* sayHelloNormal() = 0;
                extern virtual CHello* sayHelloRev() = 0;
                extern virtual CHello* sayHelloWorld() = 0;
};

//CHello.cpp
class CHello{
        public:
                virtual void say() = 0;
};

//HelloLinFact.cpp
class HelloLinFact : public HFact {
        public:
                CHello* getHelloNormal() {
                        return new HelloLinNormal;
                }

                CHello* getHelloReversed(){
                        return new HelloLinReversed;
                }

                CHello* getHelloWorld(){
                        return new HelloLinWorld;
                }
};

//HelloLinNormal.cpp
#include <iostream>

class HelloLinNormal : public CHello(){
        public:
                void say(){
                        cout>>"HelloNormal class says: Hello!";
                }
}

//HelloLinReversed.cpp
#include <iostream>

class HelloLinReversed : public CHello{
        public:
                void say(){
                        cout<<"HelloLinReversed says: olleH";
                }
}

//HelloLinWorld.cpp
#include <iostream>

class HelloLinWorld : CHello{
        public:
                void say(){
                        cout<<"HelloLinWorld says: Hello World!";
                }
}

g++  file1.cpp file2.cpp file3.cpp -o myprogram