大家来帮忙看看这个关于模板的问题。
以下是截取源至一篇文章,关于模板的。学了这么多年的c++,在这些新玩意面前傻了眼,完全看不懂..........大家帮忙分解分解。
关键的就是 Traits 和binder什么的。
//How to implement graph?
template<...> class Node {...}
template<...> class Edge {...}
//Problem:
//Node points to edges and vice-versa...
//Node do not yet know edge-type (unknown template argument).
//Can not write
template<...>
class Node
{
...
Edge<?> * m_edge;
...
}
//(A) Solution:
template< typename Types >
class Node : public Types::NodeTraits { ... };
template< typename Types >
class Edge : public Types::EdgeTraits { ... };
//Now create traits (Your base class’ for nodes and edges)
template<typename NodeType,typename EdgeType>
class MyNodeTraits
{
public:
EdgeType * m_edge;
};
template<typename NodeType,typename EdgeType>
class MyEdgeTraits
{
public:
NodeType * m_node;
};
//Now bind it all together
template<
template< typename > class NodeClass,
template< typename > class EdgeClass,
template<typename,typename,typename> class NodeTraitsClass,
template<typename,typename,typename> class EdgeTraitsClass
> struct TypeBinder
{
typedef TypeBinder<
NodeClass,EdgeClass,NodeTraitsClass,EdgeTraitsClass
> BinderType;
typedef EdgeClass<BinderType> EdgeType;
typedef NodeClass<BinderType> NodeType;
typedef EdgeTraitsClass<NodeType,EdgeType > EdgeTraits;
typedef NodeTraitsClass<NodeType,EdgeType > NodeTraits;
};