polymorphism and types

Or if the function is external to the class use double dispatch.

Quote:

Original post by Dragon_Strike im using C++ and ive got something like this..

Yes, you can achieve this with a dynamic_cast:

for (int n = 0; n < as.size(); ++n){  A* a = as[n];  assert (a);  if (B1* b = dynamic_cast<B1*>(a))    foo(b);  else if (B2* b = dynamic_cast<B2*>(a))    bar(b);  else    qux(a);}

Obviously, the operation done inside the for-loop is independent of the loop itself, meaning that basic refactoring rules will involve extracting the operation into its own method:

void frobnicate(A* a){  assert (a);  if (B1* b = dynamic_cast<B1*>(a))    foo(b);  else if (B2* b = dynamic_cast<B2*>(a))    bar(b);  else    qux(a);}std::for_each(as.begin(), as.size(), frobnicate);

But then, a function whose only purpose is to dynamic-dispatch a call based on the type of a given object should always be refactored toeither a virtual member function or a visitor:

class A { virtual void frobnicate() { qux(this); } };class B1 { void frobnicate() { foo(this); } };class B2 { void frobnicate() { bar(this); } };void frobnicate(A* a) { assert(a); a -> frobnicate(); }std::for_each(as.begin(), as.size(), frobnicate);