Struct tracing::stdlib::alloc::Global

source ·
pub struct Global;
🔬This is a nightly-only experimental API. (allocator_api #32838)
Expand description

The global memory allocator.

This type implements the Allocator trait by forwarding calls to the allocator registered with the #[global_allocator] attribute if there is one, or the std crate’s default.

Note: while this type is unstable, the functionality it provides can be accessed through the free functions in alloc.

Implementations§

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impl<T> Box<T, Global>

1.0.0 · source

pub fn new(x: T) -> Box<T, Global>

Allocates memory on the heap and then places x into it.

This doesn’t actually allocate if T is zero-sized.

Examples
let five = Box::new(5);
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pub fn new_uninit() -> Box<MaybeUninit<T>, Global>

🔬This is a nightly-only experimental API. (new_uninit #63291)

Constructs a new box with uninitialized contents.

Examples
#![feature(new_uninit)]

let mut five = Box::<u32>::new_uninit();

let five = unsafe {
    // Deferred initialization:
    five.as_mut_ptr().write(5);

    five.assume_init()
};

assert_eq!(*five, 5)
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pub fn new_zeroed() -> Box<MaybeUninit<T>, Global>

🔬This is a nightly-only experimental API. (new_uninit #63291)

Constructs a new Box with uninitialized contents, with the memory being filled with 0 bytes.

See MaybeUninit::zeroed for examples of correct and incorrect usage of this method.

Examples
#![feature(new_uninit)]

let zero = Box::<u32>::new_zeroed();
let zero = unsafe { zero.assume_init() };

assert_eq!(*zero, 0)
1.33.0 · source

pub fn pin(x: T) -> Pin<Box<T, Global>>

Constructs a new Pin<Box<T>>. If T does not implement Unpin, then x will be pinned in memory and unable to be moved.

Constructing and pinning of the Box can also be done in two steps: Box::pin(x) does the same as Box::into_pin(Box::new(x)). Consider using into_pin if you already have a Box<T>, or if you want to construct a (pinned) Box in a different way than with Box::new.

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pub fn try_new(x: T) -> Result<Box<T, Global>, AllocError>

🔬This is a nightly-only experimental API. (allocator_api #32838)

Allocates memory on the heap then places x into it, returning an error if the allocation fails

This doesn’t actually allocate if T is zero-sized.

Examples
#![feature(allocator_api)]

let five = Box::try_new(5)?;
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pub fn try_new_uninit() -> Result<Box<MaybeUninit<T>, Global>, AllocError>

🔬This is a nightly-only experimental API. (allocator_api #32838)

Constructs a new box with uninitialized contents on the heap, returning an error if the allocation fails

Examples
#![feature(allocator_api, new_uninit)]

let mut five = Box::<u32>::try_new_uninit()?;

let five = unsafe {
    // Deferred initialization:
    five.as_mut_ptr().write(5);

    five.assume_init()
};

assert_eq!(*five, 5);
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pub fn try_new_zeroed() -> Result<Box<MaybeUninit<T>, Global>, AllocError>

🔬This is a nightly-only experimental API. (allocator_api #32838)

Constructs a new Box with uninitialized contents, with the memory being filled with 0 bytes on the heap

See MaybeUninit::zeroed for examples of correct and incorrect usage of this method.

Examples
#![feature(allocator_api, new_uninit)]

let zero = Box::<u32>::try_new_zeroed()?;
let zero = unsafe { zero.assume_init() };

assert_eq!(*zero, 0);
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impl<T> Box<[T], Global>

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pub fn new_uninit_slice(len: usize) -> Box<[MaybeUninit<T>], Global>

🔬This is a nightly-only experimental API. (new_uninit #63291)

Constructs a new boxed slice with uninitialized contents.

Examples
#![feature(new_uninit)]

let mut values = Box::<[u32]>::new_uninit_slice(3);

let values = unsafe {
    // Deferred initialization:
    values[0].as_mut_ptr().write(1);
    values[1].as_mut_ptr().write(2);
    values[2].as_mut_ptr().write(3);

    values.assume_init()
};

assert_eq!(*values, [1, 2, 3])
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pub fn new_zeroed_slice(len: usize) -> Box<[MaybeUninit<T>], Global>

🔬This is a nightly-only experimental API. (new_uninit #63291)

Constructs a new boxed slice with uninitialized contents, with the memory being filled with 0 bytes.

See MaybeUninit::zeroed for examples of correct and incorrect usage of this method.

Examples
#![feature(new_uninit)]

let values = Box::<[u32]>::new_zeroed_slice(3);
let values = unsafe { values.assume_init() };

assert_eq!(*values, [0, 0, 0])
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pub fn try_new_uninit_slice(
    len: usize
) -> Result<Box<[MaybeUninit<T>], Global>, AllocError>

🔬This is a nightly-only experimental API. (allocator_api #32838)

Constructs a new boxed slice with uninitialized contents. Returns an error if the allocation fails

Examples
#![feature(allocator_api, new_uninit)]

let mut values = Box::<[u32]>::try_new_uninit_slice(3)?;
let values = unsafe {
    // Deferred initialization:
    values[0].as_mut_ptr().write(1);
    values[1].as_mut_ptr().write(2);
    values[2].as_mut_ptr().write(3);
    values.assume_init()
};

assert_eq!(*values, [1, 2, 3]);
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pub fn try_new_zeroed_slice(
    len: usize
) -> Result<Box<[MaybeUninit<T>], Global>, AllocError>

🔬This is a nightly-only experimental API. (allocator_api #32838)

Constructs a new boxed slice with uninitialized contents, with the memory being filled with 0 bytes. Returns an error if the allocation fails

See MaybeUninit::zeroed for examples of correct and incorrect usage of this method.

Examples
#![feature(allocator_api, new_uninit)]

let values = Box::<[u32]>::try_new_zeroed_slice(3)?;
let values = unsafe { values.assume_init() };

assert_eq!(*values, [0, 0, 0]);
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impl<T> Box<T, Global>where
    T: ?Sized,

1.4.0 · source

pub unsafe fn from_raw(raw: *mut T) -> Box<T, Global>

Constructs a box from a raw pointer.

After calling this function, the raw pointer is owned by the resulting Box. Specifically, the Box destructor will call the destructor of T and free the allocated memory. For this to be safe, the memory must have been allocated in accordance with the memory layout used by Box .

Safety

This function is unsafe because improper use may lead to memory problems. For example, a double-free may occur if the function is called twice on the same raw pointer.

The safety conditions are described in the memory layout section.

Examples

Recreate a Box which was previously converted to a raw pointer using Box::into_raw:

let x = Box::new(5);
let ptr = Box::into_raw(x);
let x = unsafe { Box::from_raw(ptr) };

Manually create a Box from scratch by using the global allocator:

use std::alloc::{alloc, Layout};

unsafe {
    let ptr = alloc(Layout::new::<i32>()) as *mut i32;
    // In general .write is required to avoid attempting to destruct
    // the (uninitialized) previous contents of `ptr`, though for this
    // simple example `*ptr = 5` would have worked as well.
    ptr.write(5);
    let x = Box::from_raw(ptr);
}

Trait Implementations§

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impl Allocator for Global

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fn allocate(&self, layout: Layout) -> Result<NonNull<[u8]>, AllocError>

🔬This is a nightly-only experimental API. (allocator_api #32838)
Attempts to allocate a block of memory. Read more
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fn allocate_zeroed(&self, layout: Layout) -> Result<NonNull<[u8]>, AllocError>

🔬This is a nightly-only experimental API. (allocator_api #32838)
Behaves like allocate, but also ensures that the returned memory is zero-initialized. Read more
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unsafe fn deallocate(&self, ptr: NonNull<u8>, layout: Layout)

🔬This is a nightly-only experimental API. (allocator_api #32838)
Deallocates the memory referenced by ptr. Read more
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unsafe fn grow(
    &self,
    ptr: NonNull<u8>,
    old_layout: Layout,
    new_layout: Layout
) -> Result<NonNull<[u8]>, AllocError>

🔬This is a nightly-only experimental API. (allocator_api #32838)
Attempts to extend the memory block. Read more
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unsafe fn grow_zeroed(
    &self,
    ptr: NonNull<u8>,
    old_layout: Layout,
    new_layout: Layout
) -> Result<NonNull<[u8]>, AllocError>

🔬This is a nightly-only experimental API. (allocator_api #32838)
Behaves like grow, but also ensures that the new contents are set to zero before being returned. Read more
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unsafe fn shrink(
    &self,
    ptr: NonNull<u8>,
    old_layout: Layout,
    new_layout: Layout
) -> Result<NonNull<[u8]>, AllocError>

🔬This is a nightly-only experimental API. (allocator_api #32838)
Attempts to shrink the memory block. Read more
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fn by_ref(&self) -> &Selfwhere
    Self: Sized,

🔬This is a nightly-only experimental API. (allocator_api #32838)
Creates a “by reference” adapter for this instance of Allocator. Read more
1.64.0 · source§

impl<T> AsFd for Box<T, Global>where
    T: AsFd,

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fn as_fd(&self) -> BorrowedFd<'_>

Borrows the file descriptor. Read more
1.63.0 · source§

impl<T> AsRawFd for Box<T, Global>where
    T: AsRawFd,

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fn as_raw_fd(&self) -> i32

Extracts the raw file descriptor. Read more
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impl<S> AsyncIterator for Box<S, Global>where
    S: AsyncIterator + Unpin + ?Sized,

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type Item = <S as AsyncIterator>::Item

🔬This is a nightly-only experimental API. (async_iterator #79024)
The type of items yielded by the async iterator.
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fn poll_next(
    self: Pin<&mut Box<S, Global>>,
    cx: &mut Context<'_>
) -> Poll<Option<<Box<S, Global> as AsyncIterator>::Item>>

🔬This is a nightly-only experimental API. (async_iterator #79024)
Attempt to pull out the next value of this async iterator, registering the current task for wakeup if the value is not yet available, and returning None if the async iterator is exhausted. Read more
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fn size_hint(&self) -> (usize, Option<usize>)

🔬This is a nightly-only experimental API. (async_iterator #79024)
Returns the bounds on the remaining length of the async iterator. Read more
1.0.0 · source§

impl<B> BufRead for Box<B, Global>where
    B: BufRead + ?Sized,

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fn fill_buf(&mut self) -> Result<&[u8], Error>

Returns the contents of the internal buffer, filling it with more data from the inner reader if it is empty. Read more
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fn consume(&mut self, amt: usize)

Tells this buffer that amt bytes have been consumed from the buffer, so they should no longer be returned in calls to read. Read more
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fn read_until(
    &mut self,
    byte: u8,
    buf: &mut Vec<u8, Global>
) -> Result<usize, Error>

Read all bytes into buf until the delimiter byte or EOF is reached. Read more
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fn read_line(&mut self, buf: &mut String) -> Result<usize, Error>

Read all bytes until a newline (the 0xA byte) is reached, and append them to the provided String buffer. Read more
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fn has_data_left(&mut self) -> Result<bool, Error>

🔬This is a nightly-only experimental API. (buf_read_has_data_left #86423)
Check if the underlying Read has any data left to be read. Read more
1.0.0 · source§

fn split(self, byte: u8) -> Split<Self> where
    Self: Sized,

Returns an iterator over the contents of this reader split on the byte byte. Read more
1.0.0 · source§

fn lines(self) -> Lines<Self> where
    Self: Sized,

Returns an iterator over the lines of this reader. Read more
1.29.0 · source§

impl Clone for Box<CStr, Global>

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fn clone(&self) -> Box<CStr, Global>

Returns a copy of the value. Read more
1.0.0 · source§

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
1.29.0 · source§

impl Clone for Box<OsStr, Global>

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fn clone(&self) -> Box<OsStr, Global>

Returns a copy of the value. Read more
1.0.0 · source§

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
1.29.0 · source§

impl Clone for Box<Path, Global>

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fn clone(&self) -> Box<Path, Global>

Returns a copy of the value. Read more
1.0.0 · source§

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
1.3.0 · source§

impl Clone for Box<str, Global>

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fn clone(&self) -> Box<str, Global>

Returns a copy of the value. Read more
1.0.0 · source§

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl Clone for Global

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fn clone(&self) -> Global

Returns a copy of the value. Read more
1.0.0 · source§

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl Debug for Global

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

Formats the value using the given formatter. Read more
1.0.0 (const: unstable) · source§

impl<T> Default for Box<[T], Global>

const: unstable · source§

fn default() -> Box<[T], Global>

Returns the “default value” for a type. Read more
1.17.0 · source§

impl Default for Box<CStr, Global>

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fn default() -> Box<CStr, Global>

Returns the “default value” for a type. Read more
1.17.0 · source§

impl Default for Box<OsStr, Global>

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fn default() -> Box<OsStr, Global>

Returns the “default value” for a type. Read more
1.0.0 · source§

impl<T> Default for Box<T, Global>where
    T: Default,

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fn default() -> Box<T, Global>

Creates a Box<T>, with the Default value for T.

1.17.0 (const: unstable) · source§

impl Default for Box<str, Global>

const: unstable · source§

fn default() -> Box<str, Global>

Returns the “default value” for a type. Read more
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impl Default for Global

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fn default() -> Global

Returns the “default value” for a type. Read more
1.8.0 · source§

impl<T> Error for Box<T, Global>where
    T: Error,

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

The lower-level source of this error, if any. Read more
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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)
Provides type based access to context intended for error reports. Read more
1.17.0 · source§

impl<T> From<&[T]> for Box<[T], Global>where
    T: Copy,

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fn from(slice: &[T]) -> Box<[T], Global>

Converts a &[T] into a Box<[T]>

This conversion allocates on the heap and performs a copy of slice and its contents.

Examples
// create a &[u8] which will be used to create a Box<[u8]>
let slice: &[u8] = &[104, 101, 108, 108, 111];
let boxed_slice: Box<[u8]> = Box::from(slice);

println!("{boxed_slice:?}");
1.17.0 · source§

impl From<&CStr> for Box<CStr, Global>

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fn from(s: &CStr) -> Box<CStr, Global>

Converts a &CStr into a Box<CStr>, by copying the contents into a newly allocated Box.

1.17.0 · source§

impl From<&OsStr> for Box<OsStr, Global>

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fn from(s: &OsStr) -> Box<OsStr, Global>

Copies the string into a newly allocated Box<OsStr>.

1.17.0 · source§

impl From<&Path> for Box<Path, Global>

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fn from(path: &Path) -> Box<Path, Global>

Creates a boxed Path from a reference.

This will allocate and clone path to it.

1.6.0 · source§

impl From<&str> for Box<dyn Error + 'static, Global>

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fn from(err: &str) -> Box<dyn Error + 'static, Global>

Converts a str into a box of dyn Error.

Examples
use std::error::Error;
use std::mem;

let a_str_error = "a str error";
let a_boxed_error = Box::<dyn Error>::from(a_str_error);
assert!(mem::size_of::<Box<dyn Error>>() == mem::size_of_val(&a_boxed_error))
1.0.0 · source§

impl<'a> From<&str> for Box<dyn Error + Send + Sync + 'a, Global>

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fn from(err: &str) -> Box<dyn Error + Send + Sync + 'a, Global>

Converts a str into a box of dyn Error + Send + Sync.

Examples
use std::error::Error;
use std::mem;

let a_str_error = "a str error";
let a_boxed_error = Box::<dyn Error + Send + Sync>::from(a_str_error);
assert!(
    mem::size_of::<Box<dyn Error + Send + Sync>>() == mem::size_of_val(&a_boxed_error))
1.17.0 · source§

impl From<&str> for Box<str, Global>

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fn from(s: &str) -> Box<str, Global>

Converts a &str into a Box<str>

This conversion allocates on the heap and performs a copy of s.

Examples
let boxed: Box<str> = Box::from("hello");
println!("{boxed}");
1.45.0 · source§

impl<T, const N: usize> From<[T; N]> for Box<[T], Global>

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fn from(array: [T; N]) -> Box<[T], Global>

Converts a [T; N] into a Box<[T]>

This conversion moves the array to newly heap-allocated memory.

Examples
let boxed: Box<[u8]> = Box::from([4, 2]);
println!("{boxed:?}");
1.20.0 · source§

impl From<CString> for Box<CStr, Global>

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fn from(s: CString) -> Box<CStr, Global>

Converts a CString into a Box<CStr> without copying or allocating.

1.45.0 · source§

impl<T> From<Cow<'_, [T]>> for Box<[T], Global>where
    T: Copy,

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fn from(cow: Cow<'_, [T]>) -> Box<[T], Global>

Converts a Cow<'_, [T]> into a Box<[T]>

When cow is the Cow::Borrowed variant, this conversion allocates on the heap and copies the underlying slice. Otherwise, it will try to reuse the owned Vec’s allocation.

1.45.0 · source§

impl From<Cow<'_, CStr>> for Box<CStr, Global>

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fn from(cow: Cow<'_, CStr>) -> Box<CStr, Global>

Converts a Cow<'a, CStr> into a Box<CStr>, by copying the contents if they are borrowed.

1.45.0 · source§

impl From<Cow<'_, OsStr>> for Box<OsStr, Global>

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fn from(cow: Cow<'_, OsStr>) -> Box<OsStr, Global>

Converts a Cow<'a, OsStr> into a Box<OsStr>, by copying the contents if they are borrowed.

1.45.0 · source§

impl From<Cow<'_, Path>> for Box<Path, Global>

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fn from(cow: Cow<'_, Path>) -> Box<Path, Global>

Creates a boxed Path from a clone-on-write pointer.

Converting from a Cow::Owned does not clone or allocate.

1.45.0 · source§

impl From<Cow<'_, str>> for Box<str, Global>

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fn from(cow: Cow<'_, str>) -> Box<str, Global>

Converts a Cow<'_, str> into a Box<str>

When cow is the Cow::Borrowed variant, this conversion allocates on the heap and copies the underlying str. Otherwise, it will try to reuse the owned String’s allocation.

Examples
use std::borrow::Cow;

let unboxed = Cow::Borrowed("hello");
let boxed: Box<str> = Box::from(unboxed);
println!("{boxed}");
let unboxed = Cow::Owned("hello".to_string());
let boxed: Box<str> = Box::from(unboxed);
println!("{boxed}");
1.22.0 · source§

impl<'a> From<Cow<'a, str>> for Box<dyn Error + 'static, Global>

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fn from(err: Cow<'a, str>) -> Box<dyn Error + 'static, Global>

Converts a Cow into a box of dyn Error.

Examples
use std::error::Error;
use std::mem;
use std::borrow::Cow;

let a_cow_str_error = Cow::from("a str error");
let a_boxed_error = Box::<dyn Error>::from(a_cow_str_error);
assert!(mem::size_of::<Box<dyn Error>>() == mem::size_of_val(&a_boxed_error))
1.22.0 · source§

impl<'a, 'b> From<Cow<'b, str>> for Box<dyn Error + Send + Sync + 'a, Global>

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fn from(err: Cow<'b, str>) -> Box<dyn Error + Send + Sync + 'a, Global>

Converts a Cow into a box of dyn Error + Send + Sync.

Examples
use std::error::Error;
use std::mem;
use std::borrow::Cow;

let a_cow_str_error = Cow::from("a str error");
let a_boxed_error = Box::<dyn Error + Send + Sync>::from(a_cow_str_error);
assert!(
    mem::size_of::<Box<dyn Error + Send + Sync>>() == mem::size_of_val(&a_boxed_error))
1.0.0 · source§

impl<'a, E> From<E> for Box<dyn Error + 'a, Global>where
    E: Error + 'a,

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fn from(err: E) -> Box<dyn Error + 'a, Global>

Converts a type of Error into a box of dyn Error.

Examples
use std::error::Error;
use std::fmt;
use std::mem;

#[derive(Debug)]
struct AnError;

impl fmt::Display for AnError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "An error")
    }
}

impl Error for AnError {}

let an_error = AnError;
assert!(0 == mem::size_of_val(&an_error));
let a_boxed_error = Box::<dyn Error>::from(an_error);
assert!(mem::size_of::<Box<dyn Error>>() == mem::size_of_val(&a_boxed_error))
1.0.0 · source§

impl<'a, E> From<E> for Box<dyn Error + Send + Sync + 'a, Global>where
    E: Error + Send + Sync + 'a,

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fn from(err: E) -> Box<dyn Error + Send + Sync + 'a, Global>

Converts a type of Error + Send + Sync into a box of dyn Error + Send + Sync.

Examples
use std::error::Error;
use std::fmt;
use std::mem;

#[derive(Debug)]
struct AnError;

impl fmt::Display for AnError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "An error")
    }
}

impl Error for AnError {}

unsafe impl Send for AnError {}

unsafe impl Sync for AnError {}

let an_error = AnError;
assert!(0 == mem::size_of_val(&an_error));
let a_boxed_error = Box::<dyn Error + Send + Sync>::from(an_error);
assert!(
    mem::size_of::<Box<dyn Error + Send + Sync>>() == mem::size_of_val(&a_boxed_error))
1.20.0 · source§

impl From<OsString> for Box<OsStr, Global>

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fn from(s: OsString) -> Box<OsStr, Global>

Converts an OsString into a Box<OsStr> without copying or allocating.

1.20.0 · source§

impl From<PathBuf> for Box<Path, Global>

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fn from(p: PathBuf) -> Box<Path, Global>

Converts a PathBuf into a Box<Path>.

This conversion currently should not allocate memory, but this behavior is not guaranteed on all platforms or in all future versions.

1.6.0 · source§

impl From<String> for Box<dyn Error + 'static, Global>

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fn from(str_err: String) -> Box<dyn Error + 'static, Global>

Converts a String into a box of dyn Error.

Examples
use std::error::Error;
use std::mem;

let a_string_error = "a string error".to_string();
let a_boxed_error = Box::<dyn Error>::from(a_string_error);
assert!(mem::size_of::<Box<dyn Error>>() == mem::size_of_val(&a_boxed_error))
1.0.0 · source§

impl From<String> for Box<dyn Error + Send + Sync + 'static, Global>

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fn from(err: String) -> Box<dyn Error + Send + Sync + 'static, Global>

Converts a String into a box of dyn Error + Send + Sync.

Examples
use std::error::Error;
use std::mem;

let a_string_error = "a string error".to_string();
let a_boxed_error = Box::<dyn Error + Send + Sync>::from(a_string_error);
assert!(
    mem::size_of::<Box<dyn Error + Send + Sync>>() == mem::size_of_val(&a_boxed_error))
1.20.0 · source§

impl From<String> for Box<str, Global>

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fn from(s: String) -> Box<str, Global>

Converts the given String to a boxed str slice that is owned.

Examples

Basic usage:

let s1: String = String::from("hello world");
let s2: Box<str> = Box::from(s1);
let s3: String = String::from(s2);

assert_eq!("hello world", s3)
1.6.0 · source§

impl<T> From<T> for Box<T, Global>

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fn from(t: T) -> Box<T, Global>

Converts a T into a Box<T>

The conversion allocates on the heap and moves t from the stack into it.

Examples
let x = 5;
let boxed = Box::new(5);

assert_eq!(Box::from(x), boxed);
1.32.0 · source§

impl<I> FromIterator<I> for Box<[I], Global>

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fn from_iter<T>(iter: T) -> Box<[I], Global>where
    T: IntoIterator<Item = I>,

Creates a value from an iterator. Read more
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impl<T> Log for Box<T, Global>where
    T: Log + ?Sized,

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fn enabled(&self, metadata: &Metadata<'_>) -> bool

Determines if a log message with the specified metadata would be logged. Read more
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fn log(&self, record: &Record<'_>)

Logs the Record. Read more
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fn flush(&self)

Flushes any buffered records.
1.0.0 · source§

impl<R> Read for Box<R, Global>where
    R: Read + ?Sized,

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fn read(&mut self, buf: &mut [u8]) -> Result<usize, Error>

Pull some bytes from this source into the specified buffer, returning how many bytes were read. Read more
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fn read_buf(&mut self, cursor: BorrowedCursor<'_>) -> Result<(), Error>

🔬This is a nightly-only experimental API. (read_buf #78485)
Pull some bytes from this source into the specified buffer. Read more
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fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> Result<usize, Error>

Like read, except that it reads into a slice of buffers. Read more
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fn is_read_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (can_vector #69941)
Determines if this Reader has an efficient read_vectored implementation. Read more
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fn read_to_end(&mut self, buf: &mut Vec<u8, Global>) -> Result<usize, Error>

Read all bytes until EOF in this source, placing them into buf. Read more
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fn read_to_string(&mut self, buf: &mut String) -> Result<usize, Error>

Read all bytes until EOF in this source, appending them to buf. Read more
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fn read_exact(&mut self, buf: &mut [u8]) -> Result<(), Error>

Read the exact number of bytes required to fill buf. Read more
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fn read_buf_exact(&mut self, cursor: BorrowedCursor<'_>) -> Result<(), Error>

🔬This is a nightly-only experimental API. (read_buf #78485)
Read the exact number of bytes required to fill cursor. Read more
1.0.0 · source§

fn by_ref(&mut self) -> &mut Selfwhere
    Self: Sized,

Creates a “by reference” adaptor for this instance of Read. Read more
1.0.0 · source§

fn bytes(self) -> Bytes<Self> where
    Self: Sized,

Transforms this Read instance to an Iterator over its bytes. Read more
1.0.0 · source§

fn chain<R>(self, next: R) -> Chain<Self, R> where
    R: Read,
    Self: Sized,

Creates an adapter which will chain this stream with another. Read more
1.0.0 · source§

fn take(self, limit: u64) -> Take<Self> where
    Self: Sized,

Creates an adapter which will read at most limit bytes from it. Read more
1.0.0 · source§

impl<S> Seek for Box<S, Global>where
    S: Seek + ?Sized,

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fn seek(&mut self, pos: SeekFrom) -> Result<u64, Error>

Seek to an offset, in bytes, in a stream. Read more
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fn stream_position(&mut self) -> Result<u64, Error>

Returns the current seek position from the start of the stream. Read more
1.55.0 · source§

fn rewind(&mut self) -> Result<(), Error>

Rewind to the beginning of a stream. Read more
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fn stream_len(&mut self) -> Result<u64, Error>

🔬This is a nightly-only experimental API. (seek_stream_len #59359)
Returns the length of this stream (in bytes). Read more
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impl Subscriber for Box<dyn Subscriber + Send + Sync + 'static, Global>

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fn register_callsite(&self, metadata: &'static Metadata<'static>) -> Interest

Registers a new callsite with this subscriber, returning whether or not the subscriber is interested in being notified about the callsite. Read more
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fn enabled(&self, metadata: &Metadata<'_>) -> bool

Returns true if a span or event with the specified metadata would be recorded. Read more
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fn max_level_hint(&self) -> Option<LevelFilter>

Returns the highest verbosity level that this Subscriber will enable, or None, if the subscriber does not implement level-based filtering or chooses not to implement this method. Read more
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fn new_span(&self, span: &Attributes<'_>) -> Id

Visit the construction of a new span, returning a new span ID for the span being constructed. Read more
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fn record(&self, span: &Id, values: &Record<'_>)

Record a set of values on a span. Read more
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fn record_follows_from(&self, span: &Id, follows: &Id)

Adds an indication that span follows from the span with the id follows. Read more
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fn event(&self, event: &Event<'_>)

Records that an Event has occurred. Read more
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fn enter(&self, span: &Id)

Records that a span has been entered. Read more
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fn exit(&self, span: &Id)

Records that a span has been exited. Read more
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fn clone_span(&self, id: &Id) -> Id

Notifies the subscriber that a span ID has been cloned. Read more
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fn try_close(&self, id: Id) -> bool

Notifies the subscriber that a span ID has been dropped, and returns true if there are now 0 IDs that refer to that span. Read more
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fn drop_span(&self, id: Id)

👎Deprecated since 0.1.2: use Subscriber::try_close instead
This method is deprecated. Read more
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fn current_span(&self) -> Current

Returns a type representing this subscriber’s view of the current span. Read more
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unsafe fn downcast_raw(&self, id: TypeId) -> Option<*const ()>

If self is the same type as the provided TypeId, returns an untyped *const pointer to that type. Otherwise, returns None. Read more
1.43.0 · source§

impl<T, const N: usize> TryFrom<Box<[T], Global>> for Box<[T; N], Global>

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fn try_from(
    boxed_slice: Box<[T], Global>
) -> Result<Box<[T; N], Global>, <Box<[T; N], Global> as TryFrom<Box<[T], Global>>>::Error>

Attempts to convert a Box<[T]> into a Box<[T; N]>.

The conversion occurs in-place and does not require a new memory allocation.

Errors

Returns the old Box<[T]> in the Err variant if boxed_slice.len() does not equal N.

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type Error = Box<[T], Global>

The type returned in the event of a conversion error.
1.66.0 · source§

impl<T, const N: usize> TryFrom<Vec<T, Global>> for Box<[T; N], Global>

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fn try_from(
    vec: Vec<T, Global>
) -> Result<Box<[T; N], Global>, <Box<[T; N], Global> as TryFrom<Vec<T, Global>>>::Error>

Attempts to convert a Vec<T> into a Box<[T; N]>.

Like Vec::into_boxed_slice, this is in-place if vec.capacity() == N, but will require a reallocation otherwise.

Errors

Returns the original Vec<T> in the Err variant if boxed_slice.len() does not equal N.

Examples

This can be used with vec! to create an array on the heap:

let state: Box<[f32; 100]> = vec![1.0; 100].try_into().unwrap();
assert_eq!(state.len(), 100);
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type Error = Vec<T, Global>

The type returned in the event of a conversion error.
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impl<T> Value for Box<T, Global>where
    T: Value + ?Sized,

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fn record(&self, key: &Field, visitor: &mut dyn Visit)

Visits this value with the given Visitor.
1.0.0 · source§

impl<W> Write for Box<W, Global>where
    W: Write + ?Sized,

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fn write(&mut self, buf: &[u8]) -> Result<usize, Error>

Write a buffer into this writer, returning how many bytes were written. Read more
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fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize, Error>

Like write, except that it writes from a slice of buffers. Read more
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fn is_write_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (can_vector #69941)
Determines if this Writer has an efficient write_vectored implementation. Read more
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fn flush(&mut self) -> Result<(), Error>

Flush this output stream, ensuring that all intermediately buffered contents reach their destination. Read more
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fn write_all(&mut self, buf: &[u8]) -> Result<(), Error>

Attempts to write an entire buffer into this writer. Read more
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fn write_fmt(&mut self, fmt: Arguments<'_>) -> Result<(), Error>

Writes a formatted string into this writer, returning any error encountered. Read more
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fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> Result<(), Error>

🔬This is a nightly-only experimental API. (write_all_vectored #70436)
Attempts to write multiple buffers into this writer. Read more
1.0.0 · source§

fn by_ref(&mut self) -> &mut Selfwhere
    Self: Sized,

Creates a “by reference” adapter for this instance of Write. Read more
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impl Copy for Global

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impl<T, U> DispatchFromDyn<Box<U, Global>> for Box<T, Global>where
    T: Unsize<U> + ?Sized,
    U: ?Sized,

Auto Trait Implementations§

Blanket Implementations§

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

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for Twhere
    T: ?Sized,

const: unstable · source§

fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for Twhere
    T: ?Sized,

const: unstable · source§

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

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

const: unstable · source§

fn from(t: T) -> T

Returns the argument unchanged.

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impl<T> Instrument for T

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fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more
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fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current Span, returning an Instrumented wrapper. Read more
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impl<T, U> Into<U> for Twhere
    U: From<T>,

const: unstable · source§

fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> ToOwned for Twhere
    T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for Twhere
    U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
const: unstable · source§

fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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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

The type returned in the event of a conversion error.
const: unstable · source§

fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<T> WithSubscriber for T

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fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self> where
    S: Into<Dispatch>,

Attaches the provided Subscriber to this type, returning a WithDispatch wrapper. Read more
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fn with_current_subscriber(self) -> WithDispatch<Self>

Attaches the current default Subscriber to this type, returning a WithDispatch wrapper. Read more