Trait std::convert::From 1.0.0
[−]
[src]
pub trait From<T> {
fn from(T) -> Self;
}Simple and safe type conversions in to Self. It is the reciprocal of
Into.
This trait is useful when performing error handling as described by
the book and is closely related to the ? operator.
When constructing a function that is capable of failing the return type
will generally be of the form Result<T, E>.
The From trait allows for simplification of error handling by providing a
means of returning a single error type that encapsulates numerous possible
erroneous situations.
This trait is not limited to error handling, rather the general case for this trait would be in any type conversions to have an explicit definition of how they are performed.
Note: this trait must not fail. If the conversion can fail, use
TryFrom or a dedicated method which returns an Option<T> or a
Result<T, E>.
Generic Implementations
Examples
String implements From<&str>:
let string = "hello".to_string(); let other_string = String::from("hello"); assert_eq!(string, other_string);Run
An example usage for error handling:
use std::io::{self, Read}; 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 file = std::fs::File::open("test")?; let mut contents = String::new(); file.read_to_string(&mut contents)?; let num: i32 = contents.trim().parse()?; Ok(num) }Run
Required Methods
fn from(T) -> Self
Performs the conversion.
Implementations on Foreign Types
impl<'a, T> From<&'a mut T> for NonZero<*mut T> where
T: ?Sized, [src]
impl<'a, T> From<&'a mut T> for NonZero<*mut T> where
T: ?Sized, impl<'a, T> From<&'a T> for NonZero<*const T> where
T: ?Sized, [src]
impl<'a, T> From<&'a T> for NonZero<*const T> where
T: ?Sized, impl<'a, T> From<&'a mut T> for NonZero<*const T> where
T: ?Sized, [src]
impl<'a, T> From<&'a mut T> for NonZero<*const T> where
T: ?Sized, Implementors
impl From<u64x2> for i64x2impl From<f32x16> for i32x16impl From<f64x2> for i32x2impl From<i8x2> for f32x2impl<'a, T> From<&'a mut T> for Unique<T> where
T: ?Sized,impl From<u64x4> for i32x4impl From<u32> for u64impl From<f32x8> for i32x8impl From<u16x4> for u64x4impl<T> From<T> for Cell<T>impl From<i32x4> for f32x4impl From<i8x4> for i16x4impl From<i8x4> for i64x4impl From<AllocErr> for CollectionAllocErrimpl From<u16x8> for i32x8impl From<f32> for f64impl From<i16x4> for u8x4impl From<i32x2> for i64x2impl From<u64x4> for u16x4impl From<i8x2> for i32x2impl From<i16x8> for u64x8impl From<i8x8> for u32x8impl From<i16x16> for u16x16impl From<f32x2> for u8x2impl From<i32x2> for f32x2impl From<i64x4> for u16x4impl From<f32x4> for i32x4impl From<i16x2> for u32x2impl From<u16x8> for u8x8impl From<i32x2> for u16x2impl From<u32x8> for u8x8impl From<f64x2> for i64x2impl From<i8x4> for u32x4impl From<u64x8> for i16x8impl From<i64x8> for u16x8impl From<u32x2> for f64x2impl From<i8x2> for i64x2impl From<f64x8> for f32x8impl From<i64x2> for f64x2impl From<i16x16> for f32x16impl From<i64x8> for u64x8impl From<f32x4> for i16x4impl From<u32x16> for i16x16impl From<i32x4> for f64x4impl From<i8x8> for u64x8impl From<f32x2> for i64x2impl From<f64x4> for i64x4impl From<u16x8> for f32x8impl From<f32x4> for u8x4impl From<i16x8> for u16x8impl From<u32x2> for f32x2impl From<i8> for isizeimpl From<u64x2> for f32x2impl From<u8x8> for u32x8impl From<u32x4> for f32x4impl From<f32x4> for i8x4impl From<i32> for i128impl From<f32x2> for i16x2impl From<i8x32> for u16x32impl From<u8x2> for u32x2impl From<u64> for u128impl From<f64x4> for u64x4impl From<f64x2> for i16x2impl From<i64x8> for u32x8impl From<f64x8> for i8x8impl From<u64x2> for f64x2impl From<i16> for f32impl From<u16x4> for i16x4impl From<u64x2> for u8x2impl From<u8> for u128impl From<i16> for i128impl From<u16> for u128impl From<i16x32> for u8x32impl From<u8x64> for i8x64impl<T> From<Unique<T>> for NonNull<T> where
T: ?Sized,impl From<i8x2> for u64x2impl From<i32x4> for i16x4impl From<u32x4> for i8x4impl From<u8x2> for i16x2impl From<u16x32> for i8x32impl From<f64x8> for u32x8impl<T> From<T> for Timpl From<f64x2> for u32x2impl From<i32x16> for u16x16impl From<f64x2> for u16x2impl From<u32x2> for u8x2impl From<u32x8> for i8x8impl From<i8x8> for i64x8impl From<i8x8> for u16x8impl From<i8> for f32impl From<u8> for u16impl From<i64x2> for i32x2impl From<i16x2> for f32x2impl From<f32x4> for u16x4impl From<usize> for AtomicUsizeimpl From<i32x8> for u8x8impl From<u32> for AtomicU32impl<'a, T> From<&'a mut T> for NonNull<T> where
T: ?Sized,impl From<u8x16> for i32x16impl From<i16> for i32impl From<i16x8> for f64x8impl From<u8> for isizeimpl From<u8x4> for f64x4impl From<i64x2> for u32x2impl From<u64x4> for f64x4impl From<u8> for f32impl From<u32x8> for i32x8impl From<u8> for charimpl From<u64x4> for i8x4impl From<u64x8> for u8x8impl From<u16> for f32impl From<u16x8> for i8x8impl From<i8x8> for f32x8impl From<u64x4> for u8x4impl From<i8x16> for u32x16impl From<f64x2> for u8x2impl From<u16x4> for i64x4impl From<i64x2> for f32x2impl From<u64x8> for u32x8impl From<i16x4> for f64x4impl From<i8x16> for i16x16impl From<i8x32> for u8x32impl From<i32x2> for i16x2impl From<u8x16> for f32x16impl From<i16x8> for i32x8impl From<u64x8> for u16x8impl From<u8x2> for f64x2impl From<i32> for i64impl From<i8x4> for f64x4impl From<i32x16> for i16x16impl From<u8x8> for i16x8impl From<u64x2> for i16x2impl From<i32x4> for u32x4impl From<f64x8> for u64x8impl From<i16x4> for f32x4impl From<i8x4> for u64x4impl From<i16x16> for u32x16impl From<f32x4> for f64x4impl From<u16x4> for u32x4impl From<i16> for isizeimpl From<!> for TryFromIntErrorimpl From<i8x4> for u16x4impl From<u64x4> for f32x4impl From<i16> for f64impl From<u32x2> for i16x2impl From<f32x8> for u64x8impl From<i32x4> for i64x4impl From<i8x2> for u32x2impl From<i8x4> for u8x4impl From<u8x32> for i16x32impl From<i16x4> for i64x4impl From<u8x2> for i64x2impl From<i64x4> for f64x4impl From<i64x8> for i16x8impl From<i32x8> for u64x8impl From<i16x4> for u16x4impl From<i32x8> for f32x8impl From<u8x4> for i32x4impl From<u16> for u32impl From<u32x2> for i8x2impl From<u8x2> for f32x2impl From<f32x16> for i16x16impl From<u32> for i64impl From<f32x8> for i8x8impl From<i32x2> for u8x2impl From<u16x16> for i16x16impl From<u16x2> for i16x2impl From<u32x8> for i16x8impl From<f64x8> for i16x8impl From<i8x8> for i32x8impl From<u64> for AtomicU64impl From<f64x2> for f32x2impl From<i16x32> for u16x32impl From<i64x2> for i16x2impl From<i64x8> for u8x8impl From<u16> for i64impl From<u32x2> for i32x2impl From<f64x4> for i16x4impl From<u8x4> for u32x4impl From<i16x8> for i8x8impl From<f64x4> for i32x4impl From<u32x16> for f32x16impl From<i64> for i128impl From<u16x32> for i16x32impl From<i64x8> for i8x8impl From<u64x8> for i8x8impl From<u32x8> for f32x8impl From<u16x4> for f64x4impl From<i8x2> for u8x2impl From<u32x16> for i32x16impl From<f32x2> for i32x2impl From<i64x8> for f64x8impl From<u8> for i32impl From<u8x4> for i16x4impl From<u16x4> for i32x4impl From<u8> for i16impl From<i64x4> for f32x4impl From<u8x8> for i32x8impl From<u64x8> for i64x8impl From<u8x8> for f64x8impl From<i64x2> for u64x2impl From<u16> for usizeimpl From<f32x8> for i16x8impl From<i32x8> for i16x8impl From<i32x16> for u32x16impl From<u16> for i32impl From<u32x4> for i64x4impl From<u8x8> for i8x8impl From<u16x2> for u64x2impl From<u8> for u32impl From<u8> for AtomicU8impl From<i8x2> for i16x2impl From<f64x8> for u16x8impl From<i32x4> for u8x4impl From<f32x8> for f64x8impl<T> From<T> for RefCell<T>impl From<u16> for f64impl From<i16x4> for u32x4impl From<f64x2> for u64x2impl From<i16> for i64impl From<u16x16> for u32x16impl From<u8x4> for i64x4impl From<i16x2> for i32x2impl From<u16x2> for i8x2impl From<i8x16> for u16x16impl From<isize> for AtomicIsizeimpl From<u32x8> for f64x8impl From<u32x4> for i32x4impl From<i64x4> for i8x4impl From<u8x8> for u16x8impl From<u64x2> for u32x2impl From<u64x8> for f64x8impl From<u32x4> for u64x4impl From<i16x2> for u16x2impl From<i16x2> for i64x2impl From<u64x4> for i16x4impl From<u16> for AtomicU16impl From<i8> for i64impl<'a, T> From<NonNull<T>> for Unique<T> where
T: ?Sized,impl From<f32x16> for u32x16impl From<u16> for u64impl From<u16x2> for u8x2impl From<u16x16> for i32x16impl From<u8x8> for f32x8impl From<i8x32> for i16x32impl From<u32x8> for u16x8impl From<f32x2> for u64x2impl From<u32x2> for u64x2impl From<i32x16> for f32x16impl From<i64x4> for u8x4impl From<u32x4> for i16x4impl From<f32x2> for u16x2impl From<i16x8> for i64x8impl From<f64x4> for u16x4impl From<u16x2> for i64x2impl From<i32x8> for i8x8impl From<u64x2> for i8x2impl From<u16> for i128impl From<i8> for i32impl From<i64x8> for i32x8impl From<u32> for f64impl From<i64x8> for f32x8impl From<u8x8> for u64x8impl From<i8> for f64impl From<f32x4> for u64x4impl From<u8x32> for u16x32impl<T> From<T> for UnsafeCell<T>impl From<i8x64> for u8x64impl From<u32x4> for u16x4impl From<u8> for f64impl From<i32> for f64impl From<u8x2> for u64x2impl From<f32x2> for i8x2impl From<i64x4> for i32x4impl From<u16x32> for u8x32impl From<f64x4> for f32x4impl From<i32x4> for u64x4impl From<u8x4> for i8x4impl From<u32x8> for u64x8impl From<i8x16> for i32x16impl From<i8> for i16impl From<u8x4> for u64x4impl From<u32x4> for f64x4impl From<i64x4> for u32x4impl From<i32x8> for u32x8impl From<u8x2> for u16x2impl From<u8x16> for i16x16impl From<i8> for AtomicI8impl From<u64x2> for u16x2impl From<u32x2> for i64x2impl From<u8x32> for i8x32impl From<i32x8> for u16x8impl From<u8> for i128impl From<i32x4> for u16x4impl From<u8x2> for i8x2impl From<u16x8> for i16x8impl From<f32x8> for u16x8impl From<f64x8> for u8x8impl From<f64x8> for i64x8impl From<u8x4> for f32x4impl From<i8x4> for f32x4impl From<f64x2> for i8x2impl From<i64x2> for u8x2impl From<i16x8> for f32x8impl From<u8> for usizeimpl From<i16> for AtomicI16impl From<i32> for AtomicI32impl<T> From<T> for Option<T>impl From<i16x8> for u32x8impl From<u16x2> for i32x2impl From<u64x4> for i64x4impl From<f32x2> for f64x2impl From<f32x8> for u32x8impl From<f32x16> for u16x16impl From<u32x4> for u8x4impl From<f64x4> for i8x4impl From<i8x8> for i16x8impl From<u8x2> for i32x2impl From<u32x16> for u16x16impl From<i32x8> for f64x8impl From<i16x16> for i32x16impl From<i8x8> for f64x8impl From<i32x2> for f64x2impl<'a, T> From<&'a T> for Unique<T> where
T: ?Sized,impl From<i16x4> for u64x4impl From<u8x16> for u32x16impl From<i32x2> for u64x2impl From<u16x16> for f32x16impl From<u8x4> for u16x4impl From<i16x4> for i32x4impl From<u32x2> for u16x2impl From<f32x8> for u8x8impl From<i16x8> for u8x8impl From<i32x8> for i64x8impl From<f32x2> for u32x2impl<'a, T> From<&'a T> for NonNull<T> where
T: ?Sized,impl From<f32x4> for i64x4impl From<i32x2> for u32x2impl From<i32x2> for i8x2impl From<i64x4> for u64x4impl From<char> for u32impl From<i64x2> for u16x2impl From<i8> for i128impl From<u64x2> for i32x2impl From<u16x8> for f64x8impl From<i8x16> for f32x16impl From<i64x2> for i8x2impl From<u64> for i128impl From<u16x8> for i64x8impl From<u64x8> for f32x8impl From<u16x4> for u8x4impl From<i8x2> for u16x2impl From<i16x2> for f64x2impl From<i64> for AtomicI64impl From<u16x8> for u32x8impl From<u16x4> for i8x4impl From<u8> for u64impl From<f64x4> for u8x4impl From<i16x2> for u64x2impl From<u32x8> for i64x8impl From<f32x4> for u32x4impl<T> From<*mut T> for AtomicPtr<T>impl From<u16x2> for f64x2impl From<u16x2> for u32x2impl From<i16x4> for i8x4impl From<i16x32> for i8x32impl From<i8x4> for i32x4impl From<f64x4> for u32x4impl From<u8> for i64impl From<bool> for AtomicBoolimpl From<u32> for i128impl From<i64x4> for i16x4impl From<i8x8> for u8x8impl From<u64x4> for u32x4impl From<u16x2> for f32x2impl From<u8x16> for u16x16impl From<u16x4> for f32x4impl From<f64x8> for i32x8impl From<i8x2> for f64x2impl From<u64x8> for i32x8impl From<u16x8> for u64x8impl From<u8x8> for i64x8impl From<f32x8> for i64x8impl From<u32> for u128impl From<i32x4> for i8x4impl<'a> From<&'a str> for Box<str>impl<'a> From<&'a str> for Arc<str>impl<T> From<Box<T>> for PinBox<T> where
T: ?Sized,impl<T> From<PinBox<T>> for Box<T> where
T: Unpin + ?Sized,impl From<String> for Box<str>impl<'a, T> From<&'a [T]> for Cow<'a, [T]> where
T: Clone,impl<'a, T> From<&'a mut [T]> for Vec<T> where
T: Clone,impl<'a> From<String> for Cow<'a, str>impl<'a, T> From<Cow<'a, [T]>> for Vec<T> where
[T]: ToOwned,
<[T] as ToOwned>::Owned == Vec<T>,impl<'a> From<&'a str> for Rc<str>impl<T> From<Box<T>> for Arc<T> where
T: ?Sized,impl<'a> From<&'a str> for Stringimpl<'a, T> From<&'a [T]> for Box<[T]> where
T: Copy,impl<T> From<T> for Rc<T>impl<'a> From<Cow<'a, str>> for Stringimpl<T> From<Vec<T>> for Arc<[T]>impl From<String> for Vec<u8>impl<'a> From<&'a str> for Vec<u8>impl<T> From<BinaryHeap<T>> for Vec<T>impl<T> From<Vec<T>> for Rc<[T]>impl<T> From<Box<[T]>> for Vec<T>impl<'a, T> From<&'a [T]> for Arc<[T]> where
T: Clone,impl<T> From<Vec<T>> for Box<[T]>impl<T> From<Box<T>> for Rc<T> where
T: ?Sized,impl From<String> for Arc<str>impl<T> From<VecDeque<T>> for Vec<T>impl From<Box<str>> for Box<[u8]>impl From<Box<str>> for Stringimpl<'a> From<&'a str> for Cow<'a, str>impl<T> From<T> for Arc<T>impl<'a, T> From<&'a [T]> for Rc<[T]> where
T: Clone,impl<T> From<T> for Box<T>impl<'a, T> From<Vec<T>> for Cow<'a, [T]> where
T: Clone,impl<'a, T> From<&'a [T]> for Vec<T> where
T: Clone,impl From<String> for Rc<str>impl<T> From<Vec<T>> for VecDeque<T>impl<T> From<Vec<T>> for BinaryHeap<T> where
T: Ord,impl<'a, E: Error + 'a> From<E> for Box<Error + 'a>impl<'a, E: Error + Send + Sync + 'a> From<E> for Box<Error + Send + Sync + 'a>impl From<String> for Box<Error + Send + Sync>impl From<String> for Box<Error>impl<'a, 'b> From<&'b str> for Box<Error + Send + Sync + 'a>impl<'a> From<&'a str> for Box<Error>impl<'a, 'b> From<Cow<'b, str>> for Box<Error + Send + Sync + 'a>impl<'a> From<Cow<'a, str>> for Box<Error>impl From<CString> for Vec<u8>impl<'a> From<&'a CStr> for Box<CStr>impl From<Box<CStr>> for CStringimpl From<CString> for Box<CStr>impl From<CString> for Arc<CStr>impl<'a> From<&'a CStr> for Arc<CStr>impl From<CString> for Rc<CStr>impl<'a> From<&'a CStr> for Rc<CStr>impl From<NulError> for Errorimpl<'a> From<&'a CStr> for CStringimpl From<String> for OsStringimpl<'a, T: ?Sized + AsRef<OsStr>> From<&'a T> for OsStringimpl<'a> From<&'a OsStr> for Box<OsStr>impl From<Box<OsStr>> for OsStringimpl From<OsString> for Box<OsStr>impl From<OsString> for Arc<OsStr>impl<'a> From<&'a OsStr> for Arc<OsStr>impl From<OsString> for Rc<OsStr>impl<'a> From<&'a OsStr> for Rc<OsStr>impl<W> From<IntoInnerError<W>> for Errorimpl From<ErrorKind> for Errorimpl From<Ipv4Addr> for IpAddrimpl From<Ipv6Addr> for IpAddrimpl From<Ipv4Addr> for u32impl From<u32> for Ipv4Addrimpl From<[u8; 4]> for Ipv4Addrimpl From<[u8; 4]> for IpAddrimpl From<Ipv6Addr> for u128impl From<u128> for Ipv6Addrimpl From<[u8; 16]> for Ipv6Addrimpl From<[u16; 8]> for Ipv6Addrimpl From<[u8; 16]> for IpAddrimpl From<[u16; 8]> for IpAddrimpl From<SocketAddrV4> for SocketAddrimpl From<SocketAddrV6> for SocketAddrimpl<I: Into<IpAddr>> From<(I, u16)> for SocketAddrimpl<'a> From<&'a Path> for Box<Path>impl From<Box<Path>> for PathBufimpl From<PathBuf> for Box<Path>impl<'a, T: ?Sized + AsRef<OsStr>> From<&'a T> for PathBufimpl From<OsString> for PathBufimpl From<PathBuf> for OsStringimpl From<String> for PathBufimpl<'a> From<&'a Path> for Cow<'a, Path>impl<'a> From<PathBuf> for Cow<'a, Path>impl From<PathBuf> for Arc<Path>impl<'a> From<&'a Path> for Arc<Path>impl From<PathBuf> for Rc<Path>impl<'a> From<&'a Path> for Rc<Path>impl From<ChildStdin> for Stdioimpl From<ChildStdout> for Stdioimpl From<ChildStderr> for Stdioimpl From<File> for Stdioimpl<T> From<SendError<T>> for TrySendError<T>impl From<RecvError> for TryRecvErrorimpl From<RecvError> for RecvTimeoutErrorimpl<T> From<T> for Mutex<T>impl<T> From<T> for RwLock<T>impl<T> From<PoisonError<T>> for TryLockError<T>