Question

Here is the code I have…

struct Test {
  string foo() { return "bar"; }
};

#define callFn(obj,method) obj->method();

int main() {
  Test* t = new Test();
  cout << callFn(t,foo); // bar
  return 0;
}

…and here is the code I’d like to have

int main() {
  Test* t = new Test();
  string method = "foo";
  cout << callFn(t,method); // bar
  return 0;
}

Is it possible?

Answer 1

You probably want something like member function pointers:

typedef std::string (Test::*ptmf)();

#define CALL_MF(pobject, p) (((pobject)->*(p))())

int main()
{
    ptmf method = &Test::foo;
    Test * t = new Test;
    std::string result = CALL_MF(t, method);   // or directly: (t->*method)()
}

You can create containers whose elements are of type ptmf to manage different member function pointers at runtime:

std::map<int, ptmf> function_registry;

std::string call(int key, Test * t)
{
    auto it = function_registry.find(key);
    return (it != function_registry.end()) ? CALL_MF(t, *it) : "[ERROR]";
}