Hi

I have many classes in my gameengine. They perform verious standard things (used in all games) but i also want to be able to do game-specific stuff with them, preferably without making inherited classes from the generic class.

Can i declare an "empty function" for the class that i fill differently depending on the game?

And maybe also add some game-specific variables?

Thanks

Erik

c++ is the language (see topic)

Since i want to remain uniformity. And be able to reuse some stuff. Often i want to do very similar stuff just modify something.

Maybe consider using entity-component system for your game engine (i.e. composition, mentioned by BitMaster).

Can i declare an "empty function" for the class that i fill differently depending on the game?

//MyClass.h - Engine header file
class MyClass
{
     public:
     void function();
     void gameSpecificFunction();
};

//MyClass.cpp - Engine source file
void MyClass::function()
{
     //Code....
}

//MyClass_Game.cpp - Game-specific source file.
void MyClass::gameSpecificFunction()
{
     //Code....
}

typedef std::function<void(float,int)> MyFunction;
 
class MyClass
{
     public:
     void SetFunctionToUse(MyFunction function) { functionToCall = function; }
 
     void CallFunction(float myFloat, int myInt)
     {
          //Check if a function has been set.
          if(functionToCall)
          {
                 //If so, call the function.
                 functionToCall(myFloat, myInt);
          }
     }
     
     private:
     MyFunction functionToCall;
};

And maybe also add some game-specific variables?

//MyClass.h - Engine header file
class MyClass
{
     public:
     void function();
     void gameSpecificFunction();
 
     private:
     int normalVariable;
     //The game-specific variables don't go here yet.
     
     private:
     //We tell the compiler a class called 'MyClass::Implementation' exists, but we don't define it yet.
     //This is a class within a class (in terms of namespace).
     class Implementation; 
     
     std::unique_ptr<Implementation> pImpl; //A pointer to the 'Implementation' class that we haven't yet defined.
};

//MyClass.cpp - Engine source file
 
//I'm including a _source_ file here, not a header file.
#include "../Game/MyClass_Implementation.cpp"
 
MyClass::gameSpecificFunction()
{
    //Call the Implementation's version of the function.
    pImpl->realFunction();
}

//MyClass_Implementation.cpp - Game-specific source file
 
//NOW we define MyClass::Implementation.
//I like to make pImpl's be 'structs' since they are public by default.
struct MyClass::Implementation
{
     //Game-specific variables.
     int meow = 357;
     
     //Game-specific function implementation
     void realFunction()
     {
           //...code...
     }
 
};