/* 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. */template <typename FO, int P, typename V>class Binder : private FO, private V {  //...  private:    template<int A>    class ArgSelect {      public:        // type if we haven't passed the bound argument yet:        typedef typename TypeOp<                    typename IfThenElse<(A<=Params::NumParams),                                        FunctorParam<Params, A>,                                        FunctorParam<Params, A-1>                                       >::ResultT::Type>::RefT                NoSkipT;        // type if we're past the bound argument:        typedef typename TypeOp<                    typename IfThenElse<(A>1),                                        FunctorParam<Params, A-1>,                                        FunctorParam<Params, A>                                       >::ResultT::Type>::RefT                SkipT;        // type of bound argument:        typedef typename TypeOp<typename V::ValueT>::RefT BindT;        // three selection cases implemented through different classes:        class NoSkip {          public:            static NoSkipT select (SkipT prev_arg, NoSkipT arg,                                   BindT bound_val) {                return arg;            }        };        class Skip {          public:            static SkipT select (SkipT prev_arg, NoSkipT arg,                                 BindT bound_val) {                return prev_arg;            }        };        class Bind {          public:            static BindT select (SkipT prev_arg, NoSkipT arg,                                 BindT bound_val) {                return bound_val;            }        };        // the actual selection function:        typedef typename SignSelectT<A-P, NoSkipT,                                     BindT, SkipT>::ResultT                ReturnT;        typedef typename SignSelectT<A-P, NoSkip,                                     Bind, Skip>::ResultT                SelectedT;        static ReturnT from (SkipT prev_arg, NoSkipT arg,                              BindT bound_val) {            return SelectedT::select (prev_arg, arg, bound_val);        }    };};