std::reference_wrapper<T>::reference_wrapper
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std::reference_wrapper
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reference_wrapper::reference_wrapper
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template< class U >
reference_wrapper( U&& x ) noexcept(/*see below*/) ;
(1)
(since C++11) reference_wrapper( U&& x ) noexcept(/*see below*/) ;
(constexpr since C++20)
reference_wrapper( const reference_wrapper& other ) noexcept;
(2)
(since C++11) (constexpr since C++20)
Constructs a new reference wrapper.
1) Converts x to
T& as if by T& t = std::forward <U>(x);, then stores a reference to t. This overload participates in overload resolution only if typename std::decay <U>::type is not the same type as reference_wrapper and the expression FUN(std::declval <U>()) is well-formed, where FUN names the set of imaginary functions
void FUN(T&) noexcept; void FUN(T&&) = delete;
2) Copy constructor. Stores a reference to other.get().
[edit] Parameters
x
-
an object to wrap
other
-
another reference wrapper
[edit] Exceptions
1)
noexcept specification:
where noexcept(noexcept(FUN(std::declval <U>())))
FUN is the set of imaginary functions described in the description above.[edit] Example
This section is incomplete
Reason: no example
Reason: no example
[edit] Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| LWG 2993 | C++11 | deleted reference_wrapper(T&&) constructor interfereswith overload resolution in some cases |
replaced with a constructor template |