std :: tuple到成员函数

Question

我仍然试图摆脱元编程,我很难过.

我想做的是创建一个类/ struct/whatever,为它提供一个std :: tuple并让它根据元组中的对象类型自动生成成员函数.目标是让类派生自MessageHandler

例如

typedef std::tuple< MessageA, MessageB, MessageC > MessageSet;

template< class T >
class MessageHandler
{
  // some magic metaprogramming would "create"...
  virtual void processMsg( const MessageA& ) = 0;
  virtual void processMsg( const MessageB& ) = 0;
  virtual void processMsg( const MessageC& ) = 0;
};

我已经读过你不能在模板中使用虚函数,但我不知道C++ 11是否仍然如此.

谢谢.

Answer 1

答案是可变参数模板,部分特化和继承:

//primary template!
template<typename T>
class MessageHandler;

//variadic template, partial specialization and inheritance!
template<typename H, typename ...T>
class MessageHandler<std::tuple<H,T...>>  : public MessageHandler<std::tuple<T...>>
{
    virtual void processMsg( const H& ) = 0;
};

template<typename T>
class MessageHandler<std::tuple<T>>
{
    virtual void processMsg( const T& ) = 0;
};