template declaration

[sajis997]

Please explain the difference between the two following template definition:

template <typename E>				// base element type
  class Position<E> {				// a node position
  public:
    E& operator*();				// get element
    Position parent() const;			// get parent
    PositionList children() const; 		// get node's children
    bool isRoot() const; 			// root node?
    bool isExternal() const; 			// external node?
  };

and

template <typename E>				// base element type
  class Position {				// a node position
  public:
    E& operator*();				// get element
    Position parent() const;			// get parent
    PositionList children() const; 		// get node's children
    bool isRoot() const; 			// root node?
    bool isExternal() const; 			// external node?
  };

I cannot understand the <E> part after the class Position. Some explanation would be helpful.


Thanks

[xismn]

The first code snippet is of a so-called template specialization. Like the name implies, you would use template specialization when having a different or unique implementation for a specific type would make more sense.

There's a good example at the bottom of this page:
http://www.cplusplus.com/doc/tutorial/templates/