command.cpp

#include <cstdio>

class Command
{
public:
  virtual void execute() = 0;
  virtual ~Command();

protected:
  Command();
};

Command::Command() {

}

Command::~Command() {

}
template <class Receiver>
class SimpleCommand : public Command
{
public:
  typedef void (Receiver:: *Action)();
  SimpleCommand(Receiver *r, Action a) : _receiver(r), _action(a) {}
  void execute()
  {
    (_receiver->*_action)();
  }
  ~SimpleCommand()
  {
  }

private:
  Receiver *_receiver;
  Action _action;
  
};

class Host
{
public:
  void welcomeGuest()
  {
    printf("Hello guest\n");
  }
};

int main()
{
  Host h;
  SimpleCommand<Host> c(&h, &Host::welcomeGuest);
  c.execute();
}