handling pointer to member functions within hierachy in C++
- by anatoli
Hi,
I'm trying to code the following situation:
I have a base class providing a framework for handling events. I'm trying to use an array of pointer-to-member-functions for that. It goes as following:
class EH { // EventHandler
virtual void something(); // just to make sure we get RTTI
public:
typedef void (EH::*func_t)();
protected:
func_t funcs_d[10];
protected:
void register_handler(int event_num, func_t f) {
funcs_d[event_num] = f;
}
public:
void handle_event(int event_num) {
(this->*(funcs_d[event_num]))();
}
};
Then the users are supposed to derive other classes from this one and provide handlers:
class DEH : public EH {
public:
typedef void (DEH::*func_t)();
void handle_event_5();
DEH() {
func_t f5 = &DEH::handle_event_5;
register_handler(5, f5); // doesn't compile
........
}
};
This code wouldn't compile, since DEH::func_t cannot be converted to EH::func_t. It makes perfect sense to me. In my case the conversion is safe since the object under this is really DEH. So I'd like to have something like that:
void EH::DEH_handle_event_5_wrapper() {
DEH *p = dynamic_cast<DEH *>(this);
assert(p != NULL);
p->handle_event_5();
}
and then instead of
func_t f5 = &DEH::handle_event_5;
register_handler(5, f5); // doesn't compile
in DEH::DEH()
put
register_handler(5, &EH::DEH_handle_event_5_wrapper);
So, finally the question (took me long enough...):
Is there a way to create those wrappers (like EH::DEH_handle_event_5_wrapper) automatically?
Or to do something similar?
What other solutions to this situation are out there?
Thanks.
