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

   1 [/
   2   Copyright 2007 John Maddock.
   3   Distributed under the Boost Software License, Version 1.0.
   4   (See accompanying file LICENSE_1_0.txt or copy at
   5   http://www.boost.org/LICENSE_1_0.txt).
   6 ]
   7
   8 [section:is_pointer is_pointer]
   9    template <class T>
  10    struct is_pointer : public __tof {};
  11
  12 __inherit If T is a (possibly cv-qualified) pointer type (includes function pointers,
  13 but excludes pointers to members) then inherits from __true_type,
  14 otherwise inherits from __false_type.
  15
  16 __std_ref 3.9.2p2 and 8.3.1.
  17
  18 __header ` #include <boost/type_traits/is_pointer.hpp>` or ` #include <boost/type_traits.hpp>`
  19
  20 [all_compilers]
  21
  22 __examples
  23
  24 [:`is_pointer<int*>` inherits from `__true_type`.]
  25
  26 [:`is_pointer<char* const>::type` is the type `__true_type`.]
  27
  28 [:`is_pointer<int (*)(long)>::value` is an integral constant
  29 expression that evaluates to /true/.]
  30
  31 [:`is_pointer<int (MyClass::*)(long)>::value` is an integral constant
  32 expression that evaluates to /false/.]
  33
  34 [:`is_pointer<int (MyClass::*)>::value` is an integral constant
  35 expression that evaluates to /false/.]
  36
  37 [:`is_pointer<T>::value_type` is the type `bool`.]
  38
  39 [important `is_pointer` detects "real" pointer types only, and /not/ smart pointers.
  40 Users should not specialise `is_pointer` for smart pointer types, as doing so may cause
  41 Boost (and other third party) code to fail to function correctly.
  42 Users wanting a trait to detect smart pointers should create their own.
  43 However, note that there is no way in general to auto-magically detect smart pointer types,
  44 so such a trait would have to be partially specialised for each supported smart pointer type.]
  45
  46 [endsect]
  47