example.cpp

#include <tr1/functional>
#include <cstdio>


struct FooSyncIface {
  virtual int bar(int arg) = 0;
  virtual int baz(int arg) = 0;
};

struct FooAsyncIface {
  virtual void bar(std::tr1::function<void(int)> cob, int arg) = 0;
  virtual void baz(std::tr1::function<void(int)> cob, int arg) = 0;
};

struct FooSyncNull : virtual public FooSyncIface {
  virtual int bar(int /* arg */) {
    int _return = 0;
    return _return;
  }

  virtual int baz(int /* arg */) {
    int _return = 0;
    return _return;
  }
};

#if 0
struct FooAsyncDefaulter : virtual protected FooSyncNull , virtual public FooAsyncIface {
  using FooSyncIface::bar;
  virtual void bar(std::tr1::function<void(int)> cob, int arg) {
    int _return = static_cast<FooSyncIface*>(this)->bar(arg);
    return cob(_return);
  }

  using FooSyncIface::baz;
  virtual void baz(std::tr1::function<void(int)> cob, int arg) {
    int _return = static_cast<FooSyncIface*>(this)->baz(arg);
    return cob(_return);
  }
};
#endif

#if 0
struct FooSyncHandler {
  virtual int bar(int arg) {
    return arg+1;
  }
};
#endif

struct FooAsyncHandler : public FooAsyncIface {
  virtual int bar(int arg) {
    return arg+1;
  }
  virtual void bar(std::tr1::function<void(int)> cob, int arg) {
    return cob(bar(arg));
  }

  virtual void baz(std::tr1::function<void(int)> cob, int arg) {
    return cob(arg*2);
  }
};


void print_int(int arg) {
  printf("%d\n", arg);
}


int main() {
  FooAsyncIface* iface = new FooAsyncHandler;
  iface->bar(print_int, 2);
  iface->baz(print_int, 4);
  return 0;
}