1.0.0[−][src]Trait std::prelude::v1::From
Used to do value-to-value conversions while consuming the input value. It is the reciprocal of
Into
.
One should always prefer implementing From
over Into
because implementing From
automatically provides one with a implementation of Into
thanks to the blanket implementation in the standard library.
Only implement Into
if a conversion to a type outside the current crate is required.
From
cannot do these type of conversions because of Rust's orphaning rules.
See Into
for more details.
Prefer using Into
over using From
when specifying trait bounds on a generic function.
This way, types that directly implement Into
can be used as arguments as well.
The From
is also very useful when performing error handling. When constructing a function
that is capable of failing, the return type will generally be of the form Result<T, E>
.
The From
trait simplifies error handling by allowing a function to return a single error type
that encapsulate multiple error types. See the "Examples" section and the book for more
details.
Note: This trait must not fail. If the conversion can fail, use TryFrom
.
Generic Implementations
From<T> for U
impliesInto
<U> for T
From
is reflexive, which means thatFrom<T> for T
is implemented
Examples
String
implements From<&str>
:
An explicit conversion from a &str
to a String is done as follows:
let string = "hello".to_string(); let other_string = String::from("hello"); assert_eq!(string, other_string);
While performing error handling it is often useful to implement From
for your own error type.
By converting underlying error types to our own custom error type that encapsulates the
underlying error type, we can return a single error type without losing information on the
underlying cause. The '?' operator automatically converts the underlying error type to our
custom error type by calling Into<CliError>::into
which is automatically provided when
implementing From
. The compiler then infers which implementation of Into
should be used.
use std::fs; use std::io; use std::num; enum CliError { IoError(io::Error), ParseError(num::ParseIntError), } impl From<io::Error> for CliError { fn from(error: io::Error) -> Self { CliError::IoError(error) } } impl From<num::ParseIntError> for CliError { fn from(error: num::ParseIntError) -> Self { CliError::ParseError(error) } } fn open_and_parse_file(file_name: &str) -> Result<i32, CliError> { let mut contents = fs::read_to_string(&file_name)?; let num: i32 = contents.trim().parse()?; Ok(num) }
Required methods
fn from(T) -> Self
Performs the conversion.
Implementations on Foreign Types
impl From<Ipv6Addr> for u128
[src]
fn from(ip: Ipv6Addr) -> u128
[src]
Convert an Ipv6Addr
into a host byte order u128
.
Examples
use std::net::Ipv6Addr; let addr = Ipv6Addr::new( 0x1020, 0x3040, 0x5060, 0x7080, 0x90A0, 0xB0C0, 0xD0E0, 0xF00D, ); assert_eq!(0x102030405060708090A0B0C0D0E0F00D_u128, u128::from(addr));
impl From<Ipv4Addr> for u32
[src]
fn from(ip: Ipv4Addr) -> u32
[src]
Converts an Ipv4Addr
into a host byte order u32
.
Examples
use std::net::Ipv4Addr; let addr = Ipv4Addr::new(13, 12, 11, 10); assert_eq!(0x0d0c0b0au32, u32::from(addr));
impl From<NonZeroI64> for i64
[src]
fn from(nonzero: NonZeroI64) -> i64
[src]
impl From<u32> for f64
[src]
Converts u32
to f64
losslessly.
impl From<u8> for f64
[src]
Converts u8
to f64
losslessly.
impl From<NonZeroU128> for u128
[src]
fn from(nonzero: NonZeroU128) -> u128
[src]
impl From<u16> for u32
[src]
Converts u16
to u32
losslessly.
impl From<u32> for i128
[src]
Converts u32
to i128
losslessly.
impl From<i32> for i128
[src]
Converts i32
to i128
losslessly.
impl From<u8> for u64
[src]
Converts u8
to u64
losslessly.
impl From<u8> for u16
[src]
Converts u8
to u16
losslessly.
impl From<u16> for i128
[src]
Converts u16
to i128
losslessly.
impl From<bool> for i8
[src]
Converts a bool
to a i8
. The resulting value is 0
for false
and 1
for true
values.
Examples
assert_eq!(i8::from(true), 1); assert_eq!(i8::from(false), 0);
impl From<i64> for i128
[src]
Converts i64
to i128
losslessly.
impl From<i8> for i128
[src]
Converts i8
to i128
losslessly.
impl From<i8> for f64
[src]
Converts i8
to f64
losslessly.
impl From<NonZeroU8> for u8
[src]
impl From<f32> for f64
[src]
Converts f32
to f64
losslessly.
impl From<bool> for isize
[src]
Converts a bool
to a isize
. The resulting value is 0
for false
and 1
for true
values.
Examples
assert_eq!(isize::from(true), 1); assert_eq!(isize::from(false), 0);
impl From<u16> for u128
[src]
Converts u16
to u128
losslessly.
impl From<i8> for i32
[src]
Converts i8
to i32
losslessly.
impl From<bool> for i16
[src]
Converts a bool
to a i16
. The resulting value is 0
for false
and 1
for true
values.
Examples
assert_eq!(i16::from(true), 1); assert_eq!(i16::from(false), 0);
impl From<i8> for i64
[src]
Converts i8
to i64
losslessly.
impl From<NonZeroU32> for u32
[src]
fn from(nonzero: NonZeroU32) -> u32
[src]
impl From<NonZeroI128> for i128
[src]
fn from(nonzero: NonZeroI128) -> i128
[src]
impl From<u8> for i128
[src]
Converts u8
to i128
losslessly.
impl From<NonZeroI32> for i32
[src]
fn from(nonzero: NonZeroI32) -> i32
[src]
impl From<NonZeroU16> for u16
[src]
fn from(nonzero: NonZeroU16) -> u16
[src]
impl From<u8> for i32
[src]
Converts u8
to i32
losslessly.
impl From<u32> for i64
[src]
Converts u32
to i64
losslessly.
impl From<bool> for i128
[src]
Converts a bool
to a i128
. The resulting value is 0
for false
and 1
for true
values.
Examples
assert_eq!(i128::from(true), 1); assert_eq!(i128::from(false), 0);
impl From<bool> for u64
[src]
Converts a bool
to a u64
. The resulting value is 0
for false
and 1
for true
values.
Examples
assert_eq!(u64::from(true), 1); assert_eq!(u64::from(false), 0);
impl From<i16> for i128
[src]
Converts i16
to i128
losslessly.
impl From<i16> for f32
[src]
Converts i16
to f32
losslessly.
impl From<u8> for char
[src]
Maps a byte in 0x00..=0xFF to a char
whose code point has the same value, in U+0000..=U+00FF.
Unicode is designed such that this effectively decodes bytes with the character encoding that IANA calls ISO-8859-1. This encoding is compatible with ASCII.
Note that this is different from ISO/IEC 8859-1 a.k.a. ISO 8859-1 (with one less hyphen), which leaves some "blanks", byte values that are not assigned to any character. ISO-8859-1 (the IANA one) assigns them to the C0 and C1 control codes.
Note that this is also different from Windows-1252 a.k.a. code page 1252, which is a superset ISO/IEC 8859-1 that assigns some (not all!) blanks to punctuation and various Latin characters.
To confuse things further, on the Web
ascii
, iso-8859-1
, and windows-1252
are all aliases
for a superset of Windows-1252 that fills the remaining blanks with corresponding
C0 and C1 control codes.
impl From<bool> for u128
[src]
Converts a bool
to a u128
. The resulting value is 0
for false
and 1
for true
values.
Examples
assert_eq!(u128::from(true), 1); assert_eq!(u128::from(false), 0);
impl From<i8> for isize
[src]
Converts i8
to isize
losslessly.
impl From<u16> for i32
[src]
Converts u16
to i32
losslessly.
impl From<i8> for i16
[src]
Converts i8
to i16
losslessly.
impl From<u8> for u128
[src]
Converts u8
to u128
losslessly.
impl From<bool> for i64
[src]
Converts a bool
to a i64
. The resulting value is 0
for false
and 1
for true
values.
Examples
assert_eq!(i64::from(true), 1); assert_eq!(i64::from(false), 0);
impl From<u16> for f64
[src]
Converts u16
to f64
losslessly.
impl From<bool> for u16
[src]
Converts a bool
to a u16
. The resulting value is 0
for false
and 1
for true
values.
Examples
assert_eq!(u16::from(true), 1); assert_eq!(u16::from(false), 0);
impl From<NonZeroIsize> for isize
[src]
fn from(nonzero: NonZeroIsize) -> isize
[src]
impl From<bool> for usize
[src]
Converts a bool
to a usize
. The resulting value is 0
for false
and 1
for true
values.
Examples
assert_eq!(usize::from(true), 1); assert_eq!(usize::from(false), 0);
impl From<NonZeroU64> for u64
[src]
fn from(nonzero: NonZeroU64) -> u64
[src]
impl From<NonZeroI16> for i16
[src]
fn from(nonzero: NonZeroI16) -> i16
[src]
impl From<i32> for f64
[src]
Converts i32
to f64
losslessly.
impl From<u16> for f32
[src]
Converts u16
to f32
losslessly.
impl From<bool> for u32
[src]
Converts a bool
to a u32
. The resulting value is 0
for false
and 1
for true
values.
Examples
assert_eq!(u32::from(true), 1); assert_eq!(u32::from(false), 0);
impl From<u8> for f32
[src]
Converts u8
to f32
losslessly.
impl From<i16> for i64
[src]
Converts i16
to i64
losslessly.
impl From<i8> for f32
[src]
Converts i8
to f32
losslessly.
impl From<i16> for isize
[src]
Converts i16
to isize
losslessly.
impl From<NonZeroUsize> for usize
[src]
fn from(nonzero: NonZeroUsize) -> usize
[src]
impl From<u32> for u128
[src]
Converts u32
to u128
losslessly.
impl From<bool> for i32
[src]
Converts a bool
to a i32
. The resulting value is 0
for false
and 1
for true
values.
Examples
assert_eq!(i32::from(true), 1); assert_eq!(i32::from(false), 0);
impl From<u8> for isize
[src]
Converts u8
to isize
losslessly.
impl From<u8> for usize
[src]
Converts u8
to usize
losslessly.
impl From<i16> for i32
[src]
Converts i16
to i32
losslessly.
impl From<u16> for u64
[src]
Converts u16
to u64
losslessly.
impl From<NonZeroI8> for i8
[src]
impl From<char> for u32
[src]
impl From<u16> for i64
[src]
Converts u16
to i64
losslessly.
impl From<u8> for u32
[src]
Converts u8
to u32
losslessly.
impl From<u64> for i128
[src]
Converts u64
to i128
losslessly.
impl From<i32> for i64
[src]
Converts i32
to i64
losslessly.
impl From<u32> for u64
[src]
Converts u32
to u64
losslessly.
impl From<bool> for u8
[src]
Converts a bool
to a u8
. The resulting value is 0
for false
and 1
for true
values.
Examples
assert_eq!(u8::from(true), 1); assert_eq!(u8::from(false), 0);
impl From<u64> for u128
[src]
Converts u64
to u128
losslessly.
impl From<u8> for i64
[src]
Converts u8
to i64
losslessly.
impl From<i16> for f64
[src]
Converts i16
to f64
losslessly.
impl From<u8> for i16
[src]
Converts u8
to i16
losslessly.
impl From<u16> for usize
[src]
Converts u16
to usize
losslessly.
Implementors
impl From<ChildStdin> for Stdio
[src]
fn from(child: ChildStdin) -> Stdio
[src]
Converts a ChildStdin
into a Stdio
Examples
ChildStdin
will be converted to Stdio
using Stdio::from
under the hood.
use std::process::{Command, Stdio}; let reverse = Command::new("rev") .stdin(Stdio::piped()) .spawn() .expect("failed reverse command"); let _echo = Command::new("echo") .arg("Hello, world!") .stdout(reverse.stdin.unwrap()) // Converted into a Stdio here .output() .expect("failed echo command"); // "!dlrow ,olleH" echoed to console
impl From<PathBuf> for Arc<Path>
[src]
fn from(s: PathBuf) -> Arc<Path>
[src]
Converts a Path into a Rc by copying the Path data into a new Rc buffer.
impl From<NulError> for Error
[src]
impl From<ErrorKind> for Error
[src]
Intended for use for errors not exposed to the user, where allocating onto the heap (for normal construction via Error::new) is too costly.
impl From<OsString> for Rc<OsStr>
[src]
impl From<RecvError> for RecvTimeoutError
[src]
fn from(err: RecvError) -> RecvTimeoutError
[src]
impl From<PathBuf> for Rc<Path>
[src]
fn from(s: PathBuf) -> Rc<Path>
[src]
Converts a Path into a Rc by copying the Path data into a new Rc buffer.
impl From<CString> for Arc<CStr>
[src]
impl From<File> for Stdio
[src]
fn from(file: File) -> Stdio
[src]
Converts a File
into a Stdio
Examples
File
will be converted to Stdio
using Stdio::from
under the hood.
use std::fs::File; use std::process::Command; // With the `foo.txt` file containing `Hello, world!" let file = File::open("foo.txt").unwrap(); let reverse = Command::new("rev") .stdin(file) // Implicit File conversion into a Stdio .output() .expect("failed reverse command"); assert_eq!(reverse.stdout, b"!dlrow ,olleH");
impl From<OsString> for Arc<OsStr>
[src]
impl From<DefaultEnvKey> for OsString
[src]
impl From<RecvError> for TryRecvError
[src]
fn from(err: RecvError) -> TryRecvError
[src]
impl From<ChildStderr> for Stdio
[src]
fn from(child: ChildStderr) -> Stdio
[src]
Converts a ChildStderr
into a Stdio
Examples
use std::process::{Command, Stdio}; let reverse = Command::new("rev") .arg("non_existing_file.txt") .stderr(Stdio::piped()) .spawn() .expect("failed reverse command"); let cat = Command::new("cat") .arg("-") .stdin(reverse.stderr.unwrap()) // Converted into a Stdio here .output() .expect("failed echo command"); assert_eq!( String::from_utf8_lossy(&cat.stdout), "rev: cannot open non_existing_file.txt: No such file or directory\n" );
impl From<ChildStdout> for Stdio
[src]
fn from(child: ChildStdout) -> Stdio
[src]
Converts a ChildStdout
into a Stdio
Examples
ChildStdout
will be converted to Stdio
using Stdio::from
under the hood.
use std::process::{Command, Stdio}; let hello = Command::new("echo") .arg("Hello, world!") .stdout(Stdio::piped()) .spawn() .expect("failed echo command"); let reverse = Command::new("rev") .stdin(hello.stdout.unwrap()) // Converted into a Stdio here .output() .expect("failed reverse command"); assert_eq!(reverse.stdout, b"!dlrow ,olleH\n");
impl From<CString> for Rc<CStr>
[src]
impl From<PathBuf> for OsString
[src]
fn from(path_buf: PathBuf) -> OsString
[src]
Converts a PathBuf
into a OsString
This conversion does not allocate or copy memory.
impl From<OsString> for PathBuf
[src]
fn from(s: OsString) -> PathBuf
[src]
Converts a OsString
into a PathBuf
This conversion does not allocate or copy memory.
impl From<usize> for AtomicUsize
[src]
fn from(v: usize) -> AtomicUsize
[src]
Converts an usize
into an AtomicUsize
.
impl From<!> for Infallible
[src]
fn from(x: !) -> Infallible
[src]
impl From<Infallible> for TryFromSliceError
[src]
fn from(x: Infallible) -> TryFromSliceError
[src]
impl From<Infallible> for TryFromIntError
[src]
fn from(x: Infallible) -> TryFromIntError
[src]
impl From<isize> for AtomicIsize
[src]
fn from(v: isize) -> AtomicIsize
[src]
Converts an isize
into an AtomicIsize
.
impl From<!> for TryFromIntError
[src]
fn from(never: !) -> TryFromIntError
[src]
impl From<bool> for AtomicBool
[src]
fn from(b: bool) -> AtomicBool
[src]
Converts a bool
into an AtomicBool
.
Examples
use std::sync::atomic::AtomicBool; let atomic_bool = AtomicBool::from(true); assert_eq!(format!("{:?}", atomic_bool), "true")
impl From<LayoutErr> for TryReserveError
[src]
fn from(LayoutErr) -> TryReserveError
[src]
impl From<[u16; 8]> for IpAddr
[src]
fn from(segments: [u16; 8]) -> IpAddr
[src]
Creates an IpAddr::V6
from an eight element 16-bit array.
Examples
use std::net::{IpAddr, Ipv6Addr}; let addr = IpAddr::from([ 525u16, 524u16, 523u16, 522u16, 521u16, 520u16, 519u16, 518u16, ]); assert_eq!( IpAddr::V6(Ipv6Addr::new( 0x20d, 0x20c, 0x20b, 0x20a, 0x209, 0x208, 0x207, 0x206 )), addr );
impl From<[u16; 8]> for Ipv6Addr
[src]
impl From<[u8; 4]> for IpAddr
[src]
fn from(octets: [u8; 4]) -> IpAddr
[src]
Creates an IpAddr::V4
from a four element byte array.
Examples
use std::net::{IpAddr, Ipv4Addr}; let addr = IpAddr::from([13u8, 12u8, 11u8, 10u8]); assert_eq!(IpAddr::V4(Ipv4Addr::new(13, 12, 11, 10)), addr);
impl From<[u8; 16]> for IpAddr
[src]
fn from(octets: [u8; 16]) -> IpAddr
[src]
Creates an IpAddr::V6
from a sixteen element byte array.
Examples
use std::net::{IpAddr, Ipv6Addr}; let addr = IpAddr::from([ 25u8, 24u8, 23u8, 22u8, 21u8, 20u8, 19u8, 18u8, 17u8, 16u8, 15u8, 14u8, 13u8, 12u8, 11u8, 10u8, ]); assert_eq!( IpAddr::V6(Ipv6Addr::new( 0x1918, 0x1716, 0x1514, 0x1312, 0x1110, 0x0f0e, 0x0d0c, 0x0b0a )), addr );
impl From<[u8; 16]> for Ipv6Addr
[src]
impl From<[u8; 4]> for Ipv4Addr
[src]
fn from(octets: [u8; 4]) -> Ipv4Addr
[src]
Examples
use std::net::Ipv4Addr; let addr = Ipv4Addr::from([13u8, 12u8, 11u8, 10u8]); assert_eq!(Ipv4Addr::new(13, 12, 11, 10), addr);
impl From<i16> for AtomicI16
[src]
impl From<i32> for AtomicI32
[src]
impl From<i64> for AtomicI64
[src]
impl From<i8> for AtomicI8
[src]
impl From<u128> for Ipv6Addr
[src]
fn from(ip: u128) -> Ipv6Addr
[src]
Convert a host byte order u128
into an Ipv6Addr
.
Examples
use std::net::Ipv6Addr; let addr = Ipv6Addr::from(0x102030405060708090A0B0C0D0E0F00D_u128); assert_eq!( Ipv6Addr::new( 0x1020, 0x3040, 0x5060, 0x7080, 0x90A0, 0xB0C0, 0xD0E0, 0xF00D, ), addr);
impl From<u16> for AtomicU16
[src]
impl From<u32> for Ipv4Addr
[src]
fn from(ip: u32) -> Ipv4Addr
[src]
Converts a host byte order u32
into an Ipv4Addr
.
Examples
use std::net::Ipv4Addr; let addr = Ipv4Addr::from(0x0d0c0b0au32); assert_eq!(Ipv4Addr::new(13, 12, 11, 10), addr);
impl From<u32> for AtomicU32
[src]
impl From<u64> for AtomicU64
[src]
impl From<u8> for AtomicU8
[src]
impl From<CString> for Box<CStr>
[src]
impl From<CString> for Vec<u8>
[src]
impl From<OsString> for Box<OsStr>
[src]
impl From<Ipv4Addr> for IpAddr
[src]
impl From<Ipv6Addr> for IpAddr
[src]
impl From<SocketAddrV4> for SocketAddr
[src]
fn from(sock4: SocketAddrV4) -> SocketAddr
[src]
Converts a SocketAddrV4
into a SocketAddr::V4
.
impl From<SocketAddrV6> for SocketAddr
[src]
fn from(sock6: SocketAddrV6) -> SocketAddr
[src]
Converts a SocketAddrV6
into a SocketAddr::V6
.
impl From<PathBuf> for Box<Path>
[src]
ⓘImportant traits for Box<W>fn from(p: PathBuf) -> Box<Path>
[src]
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.
impl From<Box<CStr>> for CString
[src]
impl From<Box<Path>> for PathBuf
[src]
fn from(boxed: Box<Path>) -> PathBuf
[src]
Converts a Box<Path>
into a PathBuf
This conversion does not allocate or copy memory.
impl From<Box<OsStr>> for OsString
[src]
impl From<Box<str>> for Box<[u8]>
[src]
ⓘImportant traits for Box<W>fn from(s: Box<str>) -> Box<[u8]>
[src]
Converts a Box<str>>
into a Box<[u8]>
This conversion does not allocate on the heap and happens in place.
Examples
// create a Box<str> which will be used to create a Box<[u8]> let boxed: Box<str> = Box::from("hello"); let boxed_str: Box<[u8]> = Box::from(boxed); // create a &[u8] which will be used to create a Box<[u8]> let slice: &[u8] = &[104, 101, 108, 108, 111]; let boxed_slice = Box::from(slice); assert_eq!(boxed_slice, boxed_str);
impl From<Box<str>> for String
[src]
fn from(s: Box<str>) -> String
[src]
Converts the given boxed str
slice to a String
.
It is notable that the str
slice is owned.
Examples
Basic usage:
let s1: String = String::from("hello world"); let s2: Box<str> = s1.into_boxed_str(); let s3: String = String::from(s2); assert_eq!("hello world", s3)
impl From<String> for PathBuf
[src]
fn from(s: String) -> PathBuf
[src]
Converts a String
into a PathBuf
This conversion does not allocate or copy memory.
impl From<String> for OsString
[src]
impl From<String> for Rc<str>
[src]
impl From<String> for Arc<str>
[src]
impl From<String> for Box<dyn Error + 'static>
[src]
impl From<String> for Box<str>
[src]
ⓘImportant traits for Box<W>fn from(s: String) -> Box<str>
[src]
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)
impl From<String> for Box<dyn Error + 'static + Sync + Send>
[src]
ⓘImportant traits for Box<W>fn from(err: String) -> Box<dyn Error + 'static + Sync + Send>
[src]
Converts a String
into a box of dyn Error
+ trait@Send
+ trait@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))
impl From<String> for Vec<u8>
[src]
fn from(string: String) -> Vec<u8>
[src]
Converts the given String
to a vector Vec
that holds values of type u8
.
Examples
Basic usage:
let s1 = String::from("hello world"); let v1 = Vec::from(s1); for b in v1 { println!("{}", b); }
impl<'_> From<&'_ OsStr> for Rc<OsStr>
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impl<'_> From<&'_ Path> for Rc<Path>
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fn from(s: &Path) -> Rc<Path>
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Converts a Path into a Rc by copying the Path data into a new Rc buffer.
impl<'_> From<&'_ CStr> for Arc<CStr>
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impl<'_> From<&'_ OsStr> for Arc<OsStr>
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impl<'_> From<&'_ CStr> for CString
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impl<'_> From<&'_ Path> for Arc<Path>
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fn from(s: &Path) -> Arc<Path>
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Converts a Path into a Rc by copying the Path data into a new Rc buffer.
impl<'_> From<&'_ CStr> for Rc<CStr>
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impl<'_> From<&'_ str> for Arc<str>
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impl<'_> From<&'_ str> for Rc<str>
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impl<'_> From<&'_ str> for Box<dyn Error + 'static>
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impl<'_> From<&'_ str> for Box<str>
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ⓘImportant traits for Box<W>fn from(s: &str) -> Box<str>
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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);
impl<'_> From<&'_ str> for String
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impl<'_> From<&'_ str> for Vec<u8>
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impl<'_> From<&'_ CStr> for Box<CStr>
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impl<'_> From<&'_ OsStr> for Box<OsStr>
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impl<'_> From<&'_ Path> for Box<Path>
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impl<'_> From<&'_ String> for String
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impl<'_, T> From<&'_ T> for OsString where
T: AsRef<OsStr> + ?Sized,
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T: AsRef<OsStr> + ?Sized,
impl<'_, T> From<&'_ T> for PathBuf where
T: AsRef<OsStr> + ?Sized,
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T: AsRef<OsStr> + ?Sized,
impl<'_, T> From<&'_ T> for NonNull<T> where
T: ?Sized,
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T: ?Sized,
impl<'_, T> From<&'_ mut T> for NonNull<T> where
T: ?Sized,
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T: ?Sized,
impl<'_, T> From<&'_ [T]> for Box<[T]> where
T: Copy,
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T: Copy,
ⓘImportant traits for Box<W>fn from(slice: &[T]) -> Box<[T]>
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Converts a &[T]
into a Box<[T]>
This conversion allocates on the heap
and performs a copy of slice
.
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);
impl<'_, T> From<&'_ [T]> for Vec<T> where
T: Clone,
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T: Clone,
impl<'_, T> From<&'_ [T]> for Rc<[T]> where
T: Clone,
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T: Clone,
impl<'_, T> From<&'_ [T]> for Arc<[T]> where
T: Clone,
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T: Clone,
impl<'_, T> From<&'_ mut [T]> for Vec<T> where
T: Clone,
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T: Clone,
impl<'a> From<CString> for Cow<'a, CStr>
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impl<'a> From<&'a CString> for Cow<'a, CStr>
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impl<'a> From<Cow<'a, CStr>> for CString
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impl<'a> From<Cow<'a, Path>> for PathBuf
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impl<'a> From<OsString> for Cow<'a, OsStr>
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impl<'a> From<&'a CStr> for Cow<'a, CStr>
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impl<'a> From<&'a OsStr> for Cow<'a, OsStr>
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impl<'a> From<PathBuf> for Cow<'a, Path>
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impl<'a> From<Cow<'a, OsStr>> for OsString
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impl<'a> From<&'a PathBuf> for Cow<'a, Path>
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impl<'a> From<&'a OsString> for Cow<'a, OsStr>
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impl<'a> From<&'a Path> for Cow<'a, Path>
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impl<'a> From<&'a str> for Cow<'a, str>
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impl<'a> From<&'a String> for Cow<'a, str>
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impl<'a> From<Cow<'a, str>> for Box<dyn Error + 'static>
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impl<'a> From<Cow<'a, str>> for String
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impl<'a> From<String> for Cow<'a, str>
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impl<'a, '_> From<&'_ str> for Box<dyn Error + 'a + Sync + Send>
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ⓘImportant traits for Box<W>fn from(err: &str) -> Box<dyn Error + 'a + Sync + Send>
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Converts a str
into a box of dyn Error
+ trait@Send
+ trait@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))
impl<'a, 'b> From<Cow<'b, str>> for Box<dyn Error + 'a + Sync + Send>
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ⓘImportant traits for Box<W>fn from(err: Cow<'b, str>) -> Box<dyn Error + 'a + Sync + Send>
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Converts a Cow
into a box of dyn Error
+ trait@Send
+ trait@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))
impl<'a, E> From<E> for Box<dyn Error + 'a> where
E: 'a + Error,
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E: 'a + Error,
ⓘImportant traits for Box<W>fn from(err: E) -> Box<dyn Error + 'a>
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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 { fn description(&self) -> &str { "Description of an error" } } 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))
impl<'a, E> From<E> for Box<dyn Error + 'a + Sync + Send> where
E: 'a + Error + Send + Sync,
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E: 'a + Error + Send + Sync,
ⓘImportant traits for Box<W>fn from(err: E) -> Box<dyn Error + 'a + Sync + Send>
[src]
Converts a type of Error
+ trait@Send
+ trait@Sync
into a box of
dyn Error
+ trait@Send
+ trait@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 { fn description(&self) -> &str { "Description of an error" } } 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))
impl<'a, T> From<&'a Option<T>> for Option<&'a T>
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impl<'a, T> From<&'a Vec<T>> for Cow<'a, [T]> where
T: Clone,
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T: Clone,
impl<'a, T> From<&'a mut Option<T>> for Option<&'a mut T>
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impl<'a, T> From<Cow<'a, [T]>> for Vec<T> where
[T]: ToOwned,
<[T] as ToOwned>::Owned == Vec<T>,
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[T]: ToOwned,
<[T] as ToOwned>::Owned == Vec<T>,
impl<'a, T> From<&'a [T]> for Cow<'a, [T]> where
T: Clone,
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T: Clone,
impl<'a, T> From<Vec<T>> for Cow<'a, [T]> where
T: Clone,
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T: Clone,
impl<I> From<(I, u16)> for SocketAddr where
I: Into<IpAddr>,
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I: Into<IpAddr>,
fn from(pieces: (I, u16)) -> SocketAddr
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Converts a tuple struct (Into<IpAddr
>, u16
) into a SocketAddr
.
This conversion creates a SocketAddr::V4
for a IpAddr::V4
and creates a SocketAddr::V6
for a IpAddr::V6
.
u16
is treated as port of the newly created SocketAddr
.
impl<T> From<PoisonError<T>> for TryLockError<T>
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fn from(err: PoisonError<T>) -> TryLockError<T>
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impl<T> From<T> for RwLock<T>
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fn from(t: T) -> RwLock<T>
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Creates a new instance of an RwLock<T>
which is unlocked.
This is equivalent to RwLock::new
.
impl<T> From<SendError<T>> for TrySendError<T>
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fn from(err: SendError<T>) -> TrySendError<T>
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impl<T> From<T> for Mutex<T>
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fn from(t: T) -> Mutex<T>
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Creates a new mutex in an unlocked state ready for use.
This is equivalent to Mutex::new
.
impl<T> From<T> for T
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impl<T> From<*mut T> for AtomicPtr<T>
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impl<T> From<T> for Cell<T>
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impl<T> From<T> for UnsafeCell<T>
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fn from(t: T) -> UnsafeCell<T>
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impl<T> From<T> for RefCell<T>
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impl<T> From<T> for Poll<T>
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impl<T> From<T> for Rc<T>
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impl<T> From<T> for Arc<T>
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impl<T> From<BinaryHeap<T>> for Vec<T>
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impl<T> From<VecDeque<T>> for Vec<T>
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fn from(other: VecDeque<T>) -> Vec<T>
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Turn a VecDeque<T>
into a Vec<T>
.
This never needs to re-allocate, but does need to do O(n) data movement if the circular buffer doesn't happen to be at the beginning of the allocation.
Examples
use std::collections::VecDeque; // This one is O(1). let deque: VecDeque<_> = (1..5).collect(); let ptr = deque.as_slices().0.as_ptr(); let vec = Vec::from(deque); assert_eq!(vec, [1, 2, 3, 4]); assert_eq!(vec.as_ptr(), ptr); // This one needs data rearranging. let mut deque: VecDeque<_> = (1..5).collect(); deque.push_front(9); deque.push_front(8); let ptr = deque.as_slices().1.as_ptr(); let vec = Vec::from(deque); assert_eq!(vec, [8, 9, 1, 2, 3, 4]); assert_eq!(vec.as_ptr(), ptr);
impl<T> From<Box<[T]>> for Vec<T>
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impl<T> From<Box<T>> for Pin<Box<T>> where
T: ?Sized,
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T: ?Sized,
ⓘImportant traits for Pin<P>fn from(boxed: Box<T>) -> Pin<Box<T>>
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Converts a Box<T>
into a Pin<Box<T>>
This conversion does not allocate on the heap and happens in place.
impl<T> From<Box<T>> for Rc<T> where
T: ?Sized,
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T: ?Sized,
impl<T> From<Box<T>> for Arc<T> where
T: ?Sized,
[src]
T: ?Sized,
impl<T> From<Vec<T>> for Rc<[T]>
[src]
impl<T> From<Vec<T>> for VecDeque<T>
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fn from(other: Vec<T>) -> VecDeque<T>
[src]
Turn a Vec<T>
into a VecDeque<T>
.
This avoids reallocating where possible, but the conditions for that are
strict, and subject to change, and so shouldn't be relied upon unless the
Vec<T>
came from From<VecDeque<T>>
and hasn't been reallocated.
impl<T> From<Vec<T>> for Arc<[T]>
[src]
impl<T> From<Vec<T>> for BinaryHeap<T> where
T: Ord,
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T: Ord,
fn from(vec: Vec<T>) -> BinaryHeap<T>
[src]
Converts a Vec<T>
into a BinaryHeap<T>
.
This conversion happens in-place, and has O(n)
time complexity.
impl<T> From<Vec<T>> for Box<[T]>
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impl<T> From<T> for Option<T>
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impl<T> From<T> for Box<T>
[src]
ⓘImportant traits for Box<W>fn from(t: T) -> Box<T>
[src]
Converts a generic type 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);
impl<T> From<Unique<T>> for NonNull<T> where
T: ?Sized,
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T: ?Sized,