libs/type_traits/doc/make_void.qbk

   1 [/
   2 Copyright 2017 Glen Joseph Fernandes
   3 <glenjofe -at- gmail.com>
   4
   5 Distributed under the Boost Software License,
   6 Version 1.0. (See accompanying file LICENSE_1_0.txt
   7 or copy at http://www.boost.org/LICENSE_1_0.txt).
   8 ]
   9
  10 [section:make_void make_void]
  11
  12     template<class...>
  13     struct make_void
  14     {
  15         typedef void type;
  16     };
  17
  18     template<class... Ts>
  19     using void_t = typename make_void<Ts...>::type;
  20
  21 __type The type `void` for all `T`.
  22
  23 __header ` #include <boost/type_traits/make_void.hpp>` or ` #include <boost/type_traits.hpp>`
  24
  25 [table Examples
  26
  27 [[Expression] [Result Type]]
  28
  29 [[`make_void<int>::type`][`void`]]
  30
  31 [[`make_void<int&>::type`] [`void`]]
  32
  33 [[`make_void<int(*)(int)>::type`] [`void`]]
  34
  35 [[`make_void<int[]>::type`] [`void`]]
  36
  37 [[`make_void<int[1]>::type`] [`void`]]
  38
  39 [[`make_void<>::type`] [`void`]]
  40
  41 [[`make_void<int, int>::type`] [`void`]]
  42
  43 ]
  44
  45 [all_compilers]  However, the type alias `void_t` is only available if the compiler supports template aliases.
  46 Further, in the absence of variadic-template support, `make_void` only supports up to 5 parameters.
  47
  48 [endsect]