is_pointer.qbk 1.6 KB

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  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. [section:is_pointer is_pointer]
  8. template <class T>
  9. struct is_pointer : public __tof {};
  10. __inherit If T is a (possibly cv-qualified) pointer type (includes function pointers,
  11. but excludes pointers to members) then inherits from __true_type,
  12. otherwise inherits from __false_type.
  13. __std_ref 3.9.2p2 and 8.3.1.
  14. __header ` #include <boost/type_traits/is_pointer.hpp>` or ` #include <boost/type_traits.hpp>`
  15. [all_compilers]
  16. __examples
  17. [:`is_pointer<int*>` inherits from `__true_type`.]
  18. [:`is_pointer<char* const>::type` is the type `__true_type`.]
  19. [:`is_pointer<int (*)(long)>::value` is an integral constant
  20. expression that evaluates to /true/.]
  21. [:`is_pointer<int (MyClass::*)(long)>::value` is an integral constant
  22. expression that evaluates to /false/.]
  23. [:`is_pointer<int (MyClass::*)>::value` is an integral constant
  24. expression that evaluates to /false/.]
  25. [:`is_pointer<T>::value_type` is the type `bool`.]
  26. [important `is_pointer` detects "real" pointer types only, and /not/ smart pointers.
  27. Users should not specialise `is_pointer` for smart pointer types, as doing so may cause
  28. Boost (and other third party) code to fail to function correctly.
  29. Users wanting a trait to detect smart pointers should create their own.
  30. However, note that there is no way in general to auto-magically detect smart pointer types,
  31. so such a trait would have to be partially specialised for each supported smart pointer type.]
  32. [endsect]