has_bit_xor_assign.qbk 2.1 KB

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  1. [/
  2. (C) Copyright 2009-2011 Frederic Bron.
  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:has_bit_xor_assign has_bit_xor_assign]
  8. template <class Lhs, class Rhs=Lhs, class Ret=dont_care>
  9. struct has_bit_xor_assign : public __tof {};
  10. __inherit
  11. If (i) `lhs` of type `Lhs` and `rhs` of type `Rhs` can be used in expression `lhs^=rhs`,
  12. and (ii) `Ret=dont_care` or the result of expression `lhs^=rhs` is convertible to `Ret`
  13. then inherits from __true_type,
  14. otherwise inherits from __false_type.
  15. The default behaviour (`Ret=dont_care`) is to not check for the return value of binary `operator^=`.
  16. If `Ret` is different from the default `dont_care` type, the return value is checked to be convertible to `Ret`.
  17. Convertible to `Ret` means that the return value of the operator can be used as argument to a function expecting `Ret`:
  18. ``
  19. void f(Ret);
  20. Lhs lhs;
  21. Rhs rhs;
  22. f(lhs^=rhs); // is valid if has_bit_xor_assign<Lhs, Rhs, Ret>::value==true
  23. ``
  24. If `Ret=void`, the return type is checked to be exactly `void`.
  25. __header `#include <boost/type_traits/has_bit_xor_assign.hpp>` or `#include <boost/type_traits/has_operator.hpp>` or `#include <boost/type_traits.hpp>`
  26. [has_binary_operator_compat]
  27. __examples
  28. [:`has_bit_xor_assign<Lhs, Rhs, Ret>::value_type` is the type `bool`.]
  29. [:`has_bit_xor_assign<Lhs, Rhs, Ret>::value` is a `bool` integral constant expression.]
  30. [:`has_bit_xor_assign<int>::value` is a `bool` integral constant expression that evaluates to `true`.]
  31. [:`has_bit_xor_assign<long>` inherits from `__true_type`.]
  32. [:`has_bit_xor_assign<int, int, int>` inherits from `__true_type`.]
  33. [:`has_bit_xor_assign<const int, int>` inherits from `__false_type`.]
  34. [:`has_bit_xor_assign<int, double, bool>` inherits from `__false_type`.]
  35. [:`has_bit_xor_assign<int, int, std::string>` inherits from `__false_type`.]
  36. [*See also:] [link boost_typetraits.category.value_traits.operators Operator Type Traits]
  37. [binary_operator_known_issues has_bit_xor_assign..^=..A&..contains<T>&..[/Nothing]]
  38. [endsect]