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deduction guides for std::reference_wrapper

From cppreference.net
Utilities library
Function objects
Function invocation
(C++17) (C++23)
Identity function object
(C++20)
Old binders and adaptors
( until C++17* )
( until C++17* )
( until C++17* )
( until C++17* )
( until C++17* ) ( until C++17* ) ( until C++17* ) ( until C++17* )
( until C++20* )
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( until C++17* ) ( until C++17* )
( until C++17* ) ( until C++17* )

( until C++17* )
( until C++17* ) ( until C++17* ) ( until C++17* ) ( until C++17* )
( until C++20* )
( until C++20* )
定义于头文件 <functional>
template < typename T >
reference_wrapper ( T & ) - > reference_wrapper < T > ;
(C++17 起)

std::reference_wrapper 提供了一个 推导指引 ,用于支持推导唯一的类模板参数。

示例

缺陷报告

下列行为变更缺陷报告被追溯应用于先前发布的 C++ 标准。

缺陷报告 适用范围 发布时行为 正确行为
LWG 2981 C++17 提供了来自 reference_wrapper<T> 的冗余推导指南 已移除
LWG 2993 C++17 缺陷决议移除了用于类模板参数推导的构造函数 添加推导指南作为补偿