Member Function Pointers in VxWorks

Question

I'm writing C++ for a VxWorks application. Since VxWorks is C-based, functions that take functions pointers as arguments are not compatible with C++'s member function pointers.

I have a class (SomeClass) that is instantiated several times with 30+ member functions that I would like to be able to pass to functions like taskSpawn. I know of two ways this can be accomplished, but I'm not particularly fond of either traditional solution:

1. Use static functions to call a C function pointer on a specific object:

   static void CallFunction1(SomeClass *objectToCallFunction1On);
   static void CallFunction2(SomeClass *objectToCallFunction2On);
   ...
   static void CallFunction30(SomeClass *objectToCallFunction30On);
   
   
   void Function1();
   void Function2();
   ...
   void Function30();
   

2. Use an integer or enumerated type to specify function to call on a specific object:

   static void CallFunction(SomeClass *objectToCallFunctionOn, int functionToCall);
   
   void Function1();
   void Function2();
   ...
   void Function30();
   

I really, really dislike both of these solutions. Is there a clean, simple solution to this problem?

Answer 1

1st option is to use an array of function pointers.

static void (*functionArray[30])(SomeClass *) = {
    Function1,
    Function2,
    Function3,
    Function4
    //
};

static void CallFunction(SomeClass *objectToCallFunctionOn, int functionToCall) {
   functionArray[functionToCall](objectToCallFunctionOn);
}

---

Another option will be to do the same thing with non-type template parameters. But I think the first option solves the issue fairly.