std::reference_wrapper::reference_wrapper

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std::reference_wrapper

Member functions

reference_wrapper::reference_wrapper

reference_wrapper::operator=

reference_wrapper::getreference_wrapper::operator T&

reference_wrapper::operator()

Deduction guides(C++17)

template< class U > reference_wrapper( U&& x ) noexcept(/*see below*/) ;	(1)
reference_wrapper( const reference_wrapper& other ) noexcept;	(2)

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 only participates in overload resolution 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 is the set of imaginary functions described in the description above.

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