std::reference_wrapper<T>::reference_wrapper
From cppreference.com
< cpp | utility | functional | reference wrapper
| 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:
where noexcept(noexcept(FUN(std::declval<U>())))
FUN is the set of imaginary functions described in the description above.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 interfereswith overload resolution in some cases |
replaced with a constructor template |