1.. Data Types/Miscellaneous//void_ |100 2 3void\_ 4====== 5 6Synopsis 7-------- 8 9.. parsed-literal:: 10 11 struct void\_ 12 { 13 typedef void\_ type; 14 }; 15 16 template< typename T > struct is_void; 17 18 19Description 20----------- 21 22``void_`` is a generic type placeholder representing "nothing". 23 24.. In many cases, returning ``void_`` from a metafunction to signal 25 an absence of the requested data leads to a simpler user code than 26 having a separate metafunction specifically for the purpose of 27 performing the corresponding check. 28 29Header 30------ 31 32.. parsed-literal:: 33 34 #include <boost/mpl/void.hpp> 35 36 37See also 38-------- 39 40|Data Types|, |pair|, |empty_base|, |bool_|, |int_|, |integral_c| 41 42 43.. copyright:: Copyright � 2001-2009 Aleksey Gurtovoy and David Abrahams 44 Distributed under the Boost Software License, Version 1.0. (See accompanying 45 file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) 46