projects / ceph.git / blame
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|---|---|---|
| 7c673cae FG |
1 | [/ |
| 2 | Copyright 2014 Peter Dimov | |
| 3 | ||
| 4 | Distributed under the Boost Software License, Version 1.0. | |
| 5 | ||
| 6 | See accompanying file LICENSE_1_0.txt | |
| 7 | or copy at http://boost.org/LICENSE_1_0.txt | |
| 8 | ] | |
| 9 | ||
| 10 | [section:is_same is_same] | |
| 11 | ||
| 12 | [simplesect Authors] | |
| 13 | ||
| 14 | * Peter Dimov | |
| 15 | ||
| 16 | [endsimplesect] | |
| 17 | ||
| 18 | [section Header <boost/core/is_same.hpp>] | |
| 19 | ||
| 20 | The header `<boost/core/is_same.hpp>` defines the class template | |
| 21 | `boost::core::is_same<T1,T2>`. It defines a nested integral constant | |
| 22 | `value` which is `true` when `T1` and `T2` are the same type, and | |
| 23 | `false` when they are not. | |
| 24 | ||
| 25 | In tandem with `BOOST_TEST_TRAIT_TRUE` and `BOOST_TEST_TRAIT_FALSE`, | |
| 26 | `is_same` is useful for writing tests for traits classes that have | |
| 27 | to define specific nested types. | |
| 28 | ||
| 29 | [section Synopsis] | |
| 30 | ||
| 31 | `` | |
| 32 | namespace boost | |
| 33 | { | |
| 34 | ||
| 35 | namespace core | |
| 36 | { | |
| 37 | template<class T1, class T2> struct is_same; | |
| 38 | } | |
| 39 | ||
| 40 | } | |
| 41 | `` | |
| 42 | ||
| 43 | [endsect] | |
| 44 | ||
| 45 | [section Example] | |
| 46 | ||
| 47 | `` | |
| 48 | #include <boost/core/lightweight_test_trait.hpp> | |
| 49 | #include <boost/core/is_same.hpp> | |
| 50 | ||
| 51 | template<class T> struct X | |
| 52 | { | |
| 53 | typedef T& type; | |
| 54 | }; | |
| 55 | ||
| 56 | using boost::core::is_same; | |
| 57 | ||
| 58 | int main() | |
| 59 | { | |
| 60 | BOOST_TEST_TRAIT_TRUE(( is_same<X<int>::type, int&> )); | |
| 61 | return boost::report_errors(); | |
| 62 | } | |
| 63 | `` | |
| 64 | ||
| 65 | [endsect] | |
| 66 | ||
| 67 | [endsect] | |
| 68 | ||
| 69 | [endsect] |