Struct alloc::boxed::ThinBox

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pub struct ThinBox<T: ?Sized> { /* private fields */ }
🔬This is a nightly-only experimental API. (thin_box #92791)
Expand description

ThinBox.

用于堆分配的瘦指针,与 T 无关。

Examples

#![feature(thin_box)]
use std::boxed::ThinBox;

let five = ThinBox::new(5);
let thin_slice = ThinBox::<[i32]>::new_unsize([1, 2, 3, 4]);

use std::mem::{size_of, size_of_val};
let size_of_ptr = size_of::<*const ()>();
assert_eq!(size_of_ptr, size_of_val(&five));
assert_eq!(size_of_ptr, size_of_val(&thin_slice));
Run

Implementations§

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impl<T> ThinBox<T>

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pub fn new(value: T) -> Self

🔬This is a nightly-only experimental API. (thin_box #92791)

将类型移动到堆,并将其 Metadata 存储在堆分配而不是栈中。

Examples
#![feature(thin_box)]
use std::boxed::ThinBox;

let five = ThinBox::new(5);
Run
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impl<Dyn: ?Sized> ThinBox<Dyn>

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pub fn new_unsize<T>(value: T) -> Selfwhere T: Unsize<Dyn>,

🔬This is a nightly-only experimental API. (thin_box #92791)

将类型移动到堆,并将其 Metadata 存储在堆分配而不是栈中。

Examples
#![feature(thin_box)]
use std::boxed::ThinBox;

let thin_slice = ThinBox::<[i32]>::new_unsize([1, 2, 3, 4]);
Run

Trait Implementations§

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impl<T: ?Sized + Debug> Debug for ThinBox<T>

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fn fmt(&self, f: &mut Formatter<'_>) -> Result

使用给定的格式化程序格式化该值。 Read more
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impl<T: ?Sized> Deref for ThinBox<T>

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type Target = T

解引用后的结果类型。
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fn deref(&self) -> &T

解引用值。
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impl<T: ?Sized> DerefMut for ThinBox<T>

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fn deref_mut(&mut self) -> &mut T

可变地解引用该值。
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impl<T: ?Sized + Display> Display for ThinBox<T>

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fn fmt(&self, f: &mut Formatter<'_>) -> Result

使用给定的格式化程序格式化该值。 Read more
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impl<T: ?Sized> Drop for ThinBox<T>

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fn drop(&mut self)

执行此类型的析构函数。 Read more
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impl<T: ?Sized + Error> Error for ThinBox<T>

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fn source(&self) -> Option<&(dyn Error + 'static)>

此错误的下级来源 (如果有)。 Read more
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fn description(&self) -> &str

👎Deprecated since 1.42.0: use the Display impl or to_string()
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fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0: replaced by Error::source, which can support downcasting
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fn provide<'a>(&'a self, demand: &mut Demand<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access #99301)
提供对用于错误报告的上下文的基于类型的访问。 Read more
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impl<T: ?Sized + Send> Send for ThinBox<T>

如果 TSend,则 ThinBox<T>Send,因为数据是拥有所有权的。

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impl<T: ?Sized + Sync> Sync for ThinBox<T>

如果 TSync,则 ThinBox<T>Sync,因为数据是拥有所有权的。

Auto Trait Implementations§

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impl<T: ?Sized> RefUnwindSafe for ThinBox<T>where T: RefUnwindSafe,

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impl<T: ?Sized> Unpin for ThinBox<T>where T: Unpin,

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impl<T: ?Sized> UnwindSafe for ThinBox<T>where T: UnwindSafe,

Blanket Implementations§

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impl<T> Any for Twhere T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

获取 selfTypeIdRead more
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impl<T> Borrow<T> for Twhere T: ?Sized,

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fn borrow(&self) -> &T

从拥有的值中一成不变地借用。 Read more
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impl<T> BorrowMut<T> for Twhere T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

从拥有的值中借用。 Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

返回未更改的参数。

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impl<T, U> Into<U> for Twhere U: From<T>,

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fn into(self) -> U

调用 U::from(self)

也就是说,这种转换是 From<T> for U 实现选择执行的任何操作。

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impl<E> Provider for Ewhere E: Error + ?Sized,

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fn provide<'a>(&'a self, demand: &mut Demand<'a>)

🔬This is a nightly-only experimental API. (provide_any #96024)
数据提供者应实现此方法以提供他们能够通过使用 demand 提供的所有值。 Read more
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impl<T> ToString for Twhere T: Display + ?Sized,

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default fn to_string(&self) -> String

将给定值转换为 StringRead more
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impl<T, U> TryFrom<U> for Twhere U: Into<T>,

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type Error = Infallible

发生转换错误时返回的类型。
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

执行转换。
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impl<T, U> TryInto<U> for Twhere U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

发生转换错误时返回的类型。
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

执行转换。