c – 如何typedef一个指向方法的指针,返回一个指针的方法？

struct StateMethod;
typedef StateMethod (StateMachine:: *FuncPtr)(); 
struct StateMethod
{
  StateMethod( FuncPtr pp ) : p( pp ) { }
  operator FuncPtr() { return p; }
  FuncPtr p;
};

class StateMachine {
  StateMethod stateA();
  StateMethod stateB();
};

int main()
{
  StateMachine *fsm = new StateMachine();
  FuncPtr a = fsm->stateA();  // natural usage Syntax
  return 0;
}    

StateMethod StateMachine::stateA
{
  return stateA; // natural return Syntax
}

StateMethod StateMachine::stateB
{
  return stateB;
}