ceph/src/boost/libs/type_traits/doc/has_trivial_move_constructor.qbk

   1 [/
   2   Copyright 2007 John Maddock.
   3   Copyright 2013 Antony Polukhin.
   4   Distributed under the Boost Software License, Version 1.0.
   5   (See accompanying file LICENSE_1_0.txt or copy at
   6   http://www.boost.org/LICENSE_1_0.txt).
   7 ]
   8
   9 [section:has_trivial_move_constructor has_trivial_move_constructor]
  10
  11    template <class T>
  12    struct has_trivial_move_constructor : public __tof {};
  13
  14 __inherit If T is a (possibly cv-qualified) type with a trivial move-constructor
  15 then inherits from __true_type, otherwise inherits from __false_type.
  16
  17 If a type has a trivial move-constructor then the constructor has the same effect
  18 as copying the bits of one object to the other:
  19 calls to the constructor can be safely replaced with a call to `memcpy`.
  20
  21 __compat Without some (as yet unspecified) help from the compiler,
  22 has_trivial_move_constructor will never report that a user-defined class or struct has a
  23 trivial constructor; this is always safe, if possibly sub-optimal.
  24 In addition C++11's `decltype` is required to correctly support deleted or private
  25 move constructors.
  26 Currently (June 2015) compilers that have the necessary __intrinsics to ensure that this
  27 trait "just works" include Clang, GCC-5.1, and MSVC-12.0.
  28 You may also test to see if the necessary __intrinsics are available
  29 by checking to see if the macro `BOOST_HAS_TRIVIAL_MOVE_CONSTRUCTOR` is defined.
  30
  31
  32 __header ` #include <boost/type_traits/has_trivial_move_constructor.hpp>` or ` #include <boost/type_traits.hpp>`
  33
  34 __examples
  35
  36 [:`has_trivial_move_constructor<int>` inherits from `__true_type`.]
  37
  38 [:`has_trivial_move_constructor<char*>::type` is the type `__true_type`.]
  39
  40 [:`has_trivial_move_constructor<int (*)(long)>::value` is an integral constant
  41 expression that evaluates to /true/.]
  42
  43 [:`has_trivial_move_constructor<MyClass>::value` is an integral constant
  44 expression that evaluates to /false/.]
  45
  46 [:`has_trivial_move_constructor<T>::value_type` is the type `bool`.]
  47
  48 [endsect]
  49