std::reference_wrapper<T>::reference_wrapper

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std::reference_wrapper
Member functions
reference_wrapper::reference_wrapper
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template < class U >
reference_wrapper( U&& x ) noexcept ( /*see below*/ ) ;
(1) (since C++11)
(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()

Parameters

x - an object to wrap
other - another reference wrapper

Exceptions

1)
noexcept specification:  
noexcept ( noexcept (FUN( std::declval <U> ( ) ) ) )
where FUN

Example

This section is incomplete
Reason: no example

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 interferes
with overload resolution in some cases 		replaced with a constructor template
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