example/typelist.cpp

   1 // (C) Copyright Vesa Karvonen 2004.
   2 //
   3 // Distributed under the Boost Software License, Version 1.0.
   4 // (See accompanying file LICENSE.)
   5
   6 # include <utility>
   7 # include "static_assert.h"
   8 # include "is_same.hpp"
   9 # include "typelist.hpp"
  10
  11 // ### Testing
  12 //
  13 // To test our `TYPELIST'-macro, we'll first exercise the base
  14 // case:
  15 //<
  16 using namespace typelist;
  17
  18 STATIC_ASSERT(is_same<TYPELIST(), nil>::value);
  19 //>
  20 // Then we'll try a list of 3-types:
  21 //<
  22 STATIC_ASSERT(is_same<TYPELIST((float)
  23                                (double)
  24                                (long double)),
  25               cons<float,
  26               cons<double,
  27               cons<long double, nil> > > >::value);
  28 //>
  29 // Finally we'll try a list containing commas:
  30 //<
  31 STATIC_ASSERT
  32 (is_same<TYPELIST((std::pair<signed  char, unsigned  char>)
  33                   (std::pair<signed short, unsigned short>)
  34                   (std::pair<signed   int, unsigned   int>)
  35                   (std::pair<signed  long, unsigned  long>)),
  36  cons<std::pair<signed  char, unsigned  char>,
  37  cons<std::pair<signed short, unsigned short>,
  38  cons<std::pair<signed   int, unsigned   int>,
  39  cons<std::pair<signed  long, unsigned  long> > > > > >::value);
  40 //>
  41 //
  42 // \begin{exercise}
  43 // How can one define a ``variadic'' template metafunction? (Hint:
  44 // Consider default template arguments.)
  45 // \end{exercise}