functorparam1.hpp

C++_Templates这本书的随书源码

/* The following code example is taken from the book
 * "C++ Templates - The Complete Guide"
 * by David Vandevoorde and Nicolai M. Josuttis, Addison-Wesley, 2002
 *
 * (C) Copyright David Vandevoorde and Nicolai M. Josuttis 2002.
 * Permission to copy, use, modify, sell and distribute this software
 * is granted provided this copyright notice appears in all copies.
 * This software is provided "as is" without express or implied
 * warranty, and with no claim as to its suitability for any purpose.
 */
#include "ifthenelse.hpp"

template <typename F, int N>
class UsedFunctorParam;

template <typename F, int N>
class FunctorParam {
  private:
    class Unused {
      private:
        class Private {};
      public:
        typedef Private Type;
    };
  public:
    typedef typename IfThenElse<F::NumParams>=N,
                                UsedFunctorParam<F,N>, 
                                Unused>::ResultT::Type
            Type;
};

template <typename F>
class UsedFunctorParam<F, 1> {
  public:
    typedef typename F::Param1T Type;
};