54 lines
1.7 KiB
Markdown
54 lines
1.7 KiB
Markdown
[refwrap.const]
|
||
|
||
# 22 General utilities library [[utilities]](./#utilities)
|
||
|
||
## 22.10 Function objects [[function.objects]](function.objects#refwrap.const)
|
||
|
||
### 22.10.6 Class template reference_wrapper [[refwrap]](refwrap#const)
|
||
|
||
#### 22.10.6.2 Constructors [refwrap.const]
|
||
|
||
[ð](#lib:reference_wrapper,constructor)
|
||
|
||
`template<class U>
|
||
constexpr reference_wrapper(U&& u) noexcept(see below);
|
||
`
|
||
|
||
[1](#1)
|
||
|
||
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L11724)
|
||
|
||
Let *FUN* denote the exposition-only functionsvoid *FUN*(T&) noexcept;void *FUN*(T&&) = delete;
|
||
|
||
[2](#2)
|
||
|
||
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L11731)
|
||
|
||
*Constraints*: The expression *FUN*(declval<U>()) is well-formed andis_same_v<remove_cvref_t<U>, reference_wrapper> is false[.](#2.sentence-1)
|
||
|
||
[3](#3)
|
||
|
||
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L11736)
|
||
|
||
*Effects*: Creates a variable r as if by T& r = std::forward<U>(u),
|
||
then constructs a reference_wrapper object
|
||
that stores a reference to r[.](#3.sentence-1)
|
||
|
||
[4](#4)
|
||
|
||
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L11743)
|
||
|
||
*Remarks*: The exception specification is equivalent tonoexcept(*FUN*(declval<U>()))[.](#4.sentence-1)
|
||
|
||
[ð](#lib:reference_wrapper,constructor_)
|
||
|
||
`constexpr reference_wrapper(const reference_wrapper& x) noexcept;
|
||
`
|
||
|
||
[5](#5)
|
||
|
||
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/utilities.tex#L11755)
|
||
|
||
*Effects*: Constructs a reference_wrapper object that
|
||
stores a reference to x.get()[.](#5.sentence-1)
|