stl - C++ Unable to convert base class to derived class when registering callback -

i’d create map of callbacks different objects of same hierarchy i'm getting following error:

class responsebase { public:     virtual bool parse() = 0; };  class myresponse : public responsebase { public:     bool parse() { return true; }     void sayhello() {} };  typedef std::tr1::function<void (responsebase*)> mycallback; typedef std::map<int, mycallback> mycallbacks;  mycallbacks mycallbacks;  void registercallback(int ntype, mycallback mycallback) {     mycallbacks::iterator iter = mycallbacks.find(ntype);     if (iter == mycallbacks.end())         mycallbacks[ntype] = mycallback;     else         iter->second = mycallback; }  void callback0(responsebase *presponsebase) {} void callback1(myresponse *pmyresponse) {}  int main() {     registercallback(0, callback0); // ok     registercallback(1, callback1); // error c2664: 'void (myresponse *)' : cannot convert parameter 1 'responsebase *' 'myresponse *'      return 0; } 

but i'd avoid doing this:

void callback1(responsebase *presponsebase) {     myresponse *p = static_cast<myresponse*>(presponsebase);     p->sayhello(); } 

how can work around error?