Question

I have one base class which holds a map for function pointers like this

typedef void (BaseClass::*event_t)();
class BaseClass {
    protected:
        std::map<std::string, event_t> events;
    public:
        // Example event
        void onFoo() {
            // can be added easily to the map
        }
};

Handling this works prefect, but now i want to make BaseClass an abstract base class to derive from like this:

 class SpecificClass : public BaseClass {
     public:
         void onBar() {
             // this is gonna be difficult!
         }
 };

Although i can access the map from SpecificClass i am not able to add onBar because the event_t type is only defined for the BaseClass! Is there any possibility (maybe with templates?) which does not lead to define the event_t for each class i will use…

(It is not neccessary to use templates! Any good/suitable approach would be nice.)

More background information:

This whole thing is for a text based RPG. My base class could be called Location and the specifc one any location e.g. CivicCenter. Each Location object subscribes to my EventSystem which notifies all neccessary objects when i fire an event. Therefore i want to store in a map some pointers to private functions holding the actions with their “name” like onSetOnFire (xD) as the key.

Answer 1

After some thought and a redesign i was able to achieve what i wanted. Although i am stubborn and still using inheritance i have reimplemented the map. This is how it works now:

class Location {
    // ...

    protected:
        std::map<std::string, std::function<void(void)>> m_mEvents;
};

And now i can handle it like this:

class CivicCenter : public Location {
    public:
        CivicCenter() {
            // this is done by a macro which lookes better than this
            this->m_mEvents["onTriggerSomething"] =
                  std::bind(&CivicCenter::onTriggerSomething, this);
        }

        void onTriggerSomething() {
            // ...
        }

    // ...
};

With easy use of std::bind i am able to implement generic function pointers. When using parameters like in std::function<void(int, int)> remeber to use either boost’s _1 and _2 or lambda expressions like me:

std::function<void(int,int)> f = [=](int a, int b) {
    this->anotherFunctionWithParams(a, b);
};

But this is just pointed out due to completeness of my solution.