traits/typeop.hpp

The following code example is taken from the book
C++ Templates - The Complete Guide
by David Vandevoorde and Nicolai M. Josuttis, Addison-Wesley, 2002
© Copyright David Vandevoorde and Nicolai M. Josuttis 2002


#ifndef TYPEOP_HPP
#define TYPEOP_HPP

// primary template
/**********************************
 * typeop1.hpp:
 **********************************/
template <typename T>
class TypeOp {            // primary template
  public:
    typedef T         ArgT;
    typedef T         BareT;
    typedef T const   ConstT;
    typedef T &       RefT;
    typedef T &       RefBareT;
    typedef T const & RefConstT;
};
/**** end of typeop1.hpp ****/

// partial specialization for const
/**********************************
 * typeop2.hpp:
 **********************************/
template <typename T>
class TypeOp <T const> {  // partial specialization for const types
  public:
    typedef T const   ArgT;
    typedef T         BareT;
    typedef T const   ConstT;
    typedef T const & RefT;
    typedef T &       RefBareT;
    typedef T const & RefConstT;
};
/**** end of typeop2.hpp ****/

// partial specialization for references
/**********************************
 * typeop3.hpp:
 **********************************/
template <typename T>
class TypeOp <T&> {       // partial specialization for references
  public:
    typedef T &                         ArgT;
    typedef typename TypeOp<T>::BareT   BareT;
    typedef T const                     ConstT;
    typedef T &                         RefT;
    typedef typename TypeOp<T>::BareT & RefBareT;
    typedef T const &                   RefConstT;
};
/**** end of typeop3.hpp ****/

// full specialization for void
/**********************************
 * typeop4.hpp:
 **********************************/
template<>
class TypeOp <void> {     // full specialization for void
  public:
    typedef void       ArgT;
    typedef void       BareT;
    typedef void const ConstT;
    typedef void       RefT;
    typedef void       RefBareT;
    typedef void       RefConstT;
};
/**** end of typeop4.hpp ****/

#endif // TYPEOP_HPP