AMDG Germán Diago wrote:

Hello. I think this code should work (or convince me why not):

#include <boost/function.hpp>

class A {}; class B : public A {};

typedef boost::function<void (A &)> F;

void hello(B &) { }

int main() { F f(&hello); }

Since A & can accept Bs &, should this code work?

No it shouldn't. hello takes a B&. F can take any A& even one that isn't really a B. It would work if it were the other way around: typedef boost::function<void(B&)> F; void hello(A&) {} In Christ, Steven Watanabe