overloaded-virtual.cpp

#include <boost/shared_ptr.hpp>
#include <boost/make_shared.hpp>

class Message {
};

class Receiver {
public:
    virtual ~Receiver() { }
    virtual void receive(Message *msg) = 0;
    void receive(const boost::shared_ptr<Message>& msg) { };
    void receive1(const boost::shared_ptr<Message>& msg) { };
};

class Publisher: public Receiver {
public:
    virtual ~Publisher();

    virtual void receive(Message *msg) { }
};

int main() {
    auto m = new Message();
    auto m2 = boost::make_shared<Message>();

    Publisher p;
    p.receive(m); // OK - finds virtual method
    p.receive1(m2); // OK - method isn't overloaded

    Receiver *r = &p;
    r->receive(m2); // OK - finds overloaded method

    p.receive(m2); // COMPILE ERROR - see below

    /*

$ clang -c -Wall -std=c++11 test2.cpp
test2.cpp:33:15: error: no viable conversion from 'boost::shared_ptr<Message>' to 'Message *'
    p.receive(m2); // COMPILE ERROR
              ^~
test2.cpp:19:35: note: passing argument to parameter 'msg' here
    virtual void receive(Message *msg) { }
                                  ^
1 error generated.

     */
}