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std::any::any

STD：：任何：任何

constexpr any((1)(since C++17)
any( const any& other (2)(since C++17)
any( any&& other (3)(since C++17)
template< class ValueType > any( ValueType&& value (4)(since C++17)
template< class ValueType, class... Args > explicit any( std::in_place_type_t<ValueType>, Args&&... args (5)(since C++17)
template< class T, class U, class... Args > explicit any( std::in_place_type_t<ValueType>, std::initializer_list<U> il, Args&&... args (6)(since C++17)

构造一个新的any对象。

1%29构造一个空对象。

2-3%29拷贝%282%29或移动%283%29内容other在类型和值上与other在构造函数调用之前，或空如果other是空的。正式的，

2%29other是空的，构造的对象是空的。否则，相当于any(std::in_place<T>,std::any_cast<const T&>(other))，在哪里T中包含的对象的类型。other...

3%29other是空的，构造的对象是空的。否则，构造的对象包含other中包含的对象构造为同一类型的对象。other，将该对象视为rvalue。

4%29构造一个具有初始内容的对象(类型对象)。std::decay_t<ValueType>，，，直接初始化从std::forward<ValueType>(value).如果std::is_copy_constructible<std::decay_t<ValueType>>::value是false，这个节目的形式不太好。此重载只参与在下列情况下的重载解决方案：std::decay_t<ValueType>与any也不是专门的std::in_place_type_t，和std::is_copy_constructible_v<std::decay_t<ValueType>>是true...

5%29构造一个具有初始内容的对象(类型对象)。std::decay_t<ValueType>，，，直接-非列表-初始化从std::forward<Args>(args)...。此重载只参与以下情况下的过载解决方案：std::is_constructible_v<std::decay_t<ValueType>, Args...>和std::is_copy_constructible_v<std::decay_t<ValueType>>都是true...

6%29构造一个具有初始内容的对象(类型对象)。std::decay_t<ValueType>，，，直接-非列表-初始化从il,std::forward<Args>(args)...。此重载只参与以下情况下的过载解决方案：std::is_constructible_v<std::decay_t<ValueType>,std::initializer_list<U>&, Args...>和std::is_copy_constructible_v<std::decay_t<ValueType>>都是true...

模板参数

ValueType-contained value type

类型要求

-性病：：腐烂[医]T型<ValueType>必须符合CopyConstrucable的要求。

参数

other-another any object to copy or move from
value-value to initialize the contained value with
il, args-arguments to be passed to the constructor of the contained object

例外

1，3%29

noexcept规格：

noexcept

2，4，5，6%29抛出包含类型的构造函数引发的任何异常。

注记

因为默认构造函数是constexpr，静态std::anys被初始化为静态非局部初始化，在任何动态的非本地初始化开始之前。这使得使用类型的对象是安全的。std::any在任何静态对象的构造函数中。

另见

operator=assigns an any object (public member function)

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