ceph/src/boost/libs/type_traits/doc/is_copy_constructible.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:is_copy_constructible is_copy_constructible]
  10
  11    template <class T>
  12    struct is_copy_constructible : public __tof {};
  13
  14 __inherit If `T` is a (possibly cv-qualified) type with a copy constructor,
  15 then inherits from __true_type, otherwise inherits from __false_type.  Type `T`
  16 must be a complete type.
  17
  18 In other words, inherits from __true_type only if copy constructor of `T` not
  19 marked with `= delete`, `T` does not derives from `boost::noncopyable` and
  20 does not marked with `BOOST_MOVABLE_BUT_NOT_COPYABLE(T)`.
  21
  22 __compat This trait requires the C++11 features `decltype` and SFINAE-expression support for full support.
  23
  24 If your compiler does not support C++11 deleted functions (`= delete`) or does not support
  25 SFINAE for the deleted constructors, then derive your classes from `boost::noncopyable` or
  26 mark them with `BOOST_MOVABLE_BUT_NOT_COPYABLE(T)` to show that class is noncopyable.
  27
  28 The trait does not care about access modifiers, so if you see errors like this:
  29
  30       'T::T(const T&)' is private
  31       boost/type_traits/is_copy_constructible.hpp:68:5: error: within this context
  32
  33 then you are trying to call that macro for a structure with private constructor:
  34
  35       struct T {
  36           // ...
  37       private:
  38           T(const T &);
  39           // ...
  40       };
  41
  42 To fix that you must modify your structure, explicitly marking it as noncopyable (`= delete`,
  43 `boost::noncopyable` or `BOOST_MOVABLE_BUT_NOT_COPYABLE(T)`) or explicitly
  44 [link boost_typetraits.user_defined specialize trait].
  45
  46
  47 __header ` #include <boost/type_traits/is_copy_constructible.hpp>` or ` #include <boost/type_traits.hpp>`
  48
  49 [endsect]
  50