Enum core::result::Result 1.0.0[−][src]
#[must_use = "this `Result` may be an `Err` variant, which should be handled"]
pub enum Result<T, E> {
Ok(T),
Err(E),
}Result is a type that represents either success (Ok) or failure (Err).
See the module documentation for details.
Variants
Contains the success value
Contains the error value
Implementations
impl<T, E> Result<T, E>[src]
impl<T, E> Result<T, E>[src]#[must_use = "if you intended to assert that this is ok, consider `.unwrap()` instead"]pub const fn is_ok(&self) -> bool1.0.0 (const: 1.48.0)[src]
Returns true if the result is Ok.
Examples
Basic usage:
let x: Result<i32, &str> = Ok(-3); assert_eq!(x.is_ok(), true); let x: Result<i32, &str> = Err("Some error message"); assert_eq!(x.is_ok(), false);Run
#[must_use = "if you intended to assert that this is err, consider `.unwrap_err()` instead"]pub const fn is_err(&self) -> bool1.0.0 (const: 1.48.0)[src]
Returns true if the result is Err.
Examples
Basic usage:
let x: Result<i32, &str> = Ok(-3); assert_eq!(x.is_err(), false); let x: Result<i32, &str> = Err("Some error message"); assert_eq!(x.is_err(), true);Run
#[must_use]pub fn contains<U>(&self, x: &U) -> bool where
U: PartialEq<T>, [src]
U: PartialEq<T>,
Returns true if the result is an Ok value containing the given value.
Examples
#![feature(option_result_contains)] let x: Result<u32, &str> = Ok(2); assert_eq!(x.contains(&2), true); let x: Result<u32, &str> = Ok(3); assert_eq!(x.contains(&2), false); let x: Result<u32, &str> = Err("Some error message"); assert_eq!(x.contains(&2), false);Run
#[must_use]pub fn contains_err<F>(&self, f: &F) -> bool where
F: PartialEq<E>, [src]
F: PartialEq<E>,
Returns true if the result is an Err value containing the given value.
Examples
#![feature(result_contains_err)] let x: Result<u32, &str> = Ok(2); assert_eq!(x.contains_err(&"Some error message"), false); let x: Result<u32, &str> = Err("Some error message"); assert_eq!(x.contains_err(&"Some error message"), true); let x: Result<u32, &str> = Err("Some other error message"); assert_eq!(x.contains_err(&"Some error message"), false);Run
pub fn ok(self) -> Option<T>[src]
Converts from Result<T, E> to Option<T>.
Converts self into an Option<T>, consuming self,
and discarding the error, if any.
Examples
Basic usage:
let x: Result<u32, &str> = Ok(2); assert_eq!(x.ok(), Some(2)); let x: Result<u32, &str> = Err("Nothing here"); assert_eq!(x.ok(), None);Run
pub fn err(self) -> Option<E>[src]
Converts from Result<T, E> to Option<E>.
Converts self into an Option<E>, consuming self,
and discarding the success value, if any.
Examples
Basic usage:
let x: Result<u32, &str> = Ok(2); assert_eq!(x.err(), None); let x: Result<u32, &str> = Err("Nothing here"); assert_eq!(x.err(), Some("Nothing here"));Run
pub const fn as_ref(&self) -> Result<&T, &E>1.0.0 (const: 1.48.0)[src]
Converts from &Result<T, E> to Result<&T, &E>.
Produces a new Result, containing a reference
into the original, leaving the original in place.
Examples
Basic usage:
let x: Result<u32, &str> = Ok(2); assert_eq!(x.as_ref(), Ok(&2)); let x: Result<u32, &str> = Err("Error"); assert_eq!(x.as_ref(), Err(&"Error"));Run
pub fn as_mut(&mut self) -> Result<&mut T, &mut E>[src]
Converts from &mut Result<T, E> to Result<&mut T, &mut E>.
Examples
Basic usage:
fn mutate(r: &mut Result<i32, i32>) { match r.as_mut() { Ok(v) => *v = 42, Err(e) => *e = 0, } } let mut x: Result<i32, i32> = Ok(2); mutate(&mut x); assert_eq!(x.unwrap(), 42); let mut x: Result<i32, i32> = Err(13); mutate(&mut x); assert_eq!(x.unwrap_err(), 0);Run
pub fn map<U, F: FnOnce(T) -> U>(self, op: F) -> Result<U, E>[src]
Maps a Result<T, E> to Result<U, E> by applying a function to a
contained Ok value, leaving an Err value untouched.
This function can be used to compose the results of two functions.
Examples
Print the numbers on each line of a string multiplied by two.
let line = "1\n2\n3\n4\n"; for num in line.lines() { match num.parse::<i32>().map(|i| i * 2) { Ok(n) => println!("{}", n), Err(..) => {} } }Run
pub fn map_or<U, F: FnOnce(T) -> U>(self, default: U, f: F) -> U1.41.0[src]
Returns the provided default (if Err), or
applies a function to the contained value (if Ok),
Arguments passed to map_or are eagerly evaluated; if you are passing
the result of a function call, it is recommended to use map_or_else,
which is lazily evaluated.
Examples
let x: Result<_, &str> = Ok("foo"); assert_eq!(x.map_or(42, |v| v.len()), 3); let x: Result<&str, _> = Err("bar"); assert_eq!(x.map_or(42, |v| v.len()), 42);Run
pub fn map_or_else<U, D: FnOnce(E) -> U, F: FnOnce(T) -> U>(
self,
default: D,
f: F
) -> U1.41.0[src]
self,
default: D,
f: F
) -> U
Maps a Result<T, E> to U by applying a fallback function to a
contained Err value, or a default function to a
contained Ok value.
This function can be used to unpack a successful result while handling an error.
Examples
Basic usage:
let k = 21; let x : Result<_, &str> = Ok("foo"); assert_eq!(x.map_or_else(|e| k * 2, |v| v.len()), 3); let x : Result<&str, _> = Err("bar"); assert_eq!(x.map_or_else(|e| k * 2, |v| v.len()), 42);Run
pub fn map_err<F, O: FnOnce(E) -> F>(self, op: O) -> Result<T, F>[src]
Maps a Result<T, E> to Result<T, F> by applying a function to a
contained Err value, leaving an Ok value untouched.
This function can be used to pass through a successful result while handling an error.
Examples
Basic usage:
fn stringify(x: u32) -> String { format!("error code: {}", x) } let x: Result<u32, u32> = Ok(2); assert_eq!(x.map_err(stringify), Ok(2)); let x: Result<u32, u32> = Err(13); assert_eq!(x.map_err(stringify), Err("error code: 13".to_string()));Run
pub fn iter(&self) -> Iter<'_, T>ⓘ[src]
Returns an iterator over the possibly contained value.
The iterator yields one value if the result is Result::Ok, otherwise none.
Examples
Basic usage:
let x: Result<u32, &str> = Ok(7); assert_eq!(x.iter().next(), Some(&7)); let x: Result<u32, &str> = Err("nothing!"); assert_eq!(x.iter().next(), None);Run
pub fn iter_mut(&mut self) -> IterMut<'_, T>ⓘ[src]
Returns a mutable iterator over the possibly contained value.
The iterator yields one value if the result is Result::Ok, otherwise none.
Examples
Basic usage:
let mut x: Result<u32, &str> = Ok(7); match x.iter_mut().next() { Some(v) => *v = 40, None => {}, } assert_eq!(x, Ok(40)); let mut x: Result<u32, &str> = Err("nothing!"); assert_eq!(x.iter_mut().next(), None);Run
pub fn and<U>(self, res: Result<U, E>) -> Result<U, E>[src]
Returns res if the result is Ok, otherwise returns the Err value of self.
Examples
Basic usage:
let x: Result<u32, &str> = Ok(2); let y: Result<&str, &str> = Err("late error"); assert_eq!(x.and(y), Err("late error")); let x: Result<u32, &str> = Err("early error"); let y: Result<&str, &str> = Ok("foo"); assert_eq!(x.and(y), Err("early error")); let x: Result<u32, &str> = Err("not a 2"); let y: Result<&str, &str> = Err("late error"); assert_eq!(x.and(y), Err("not a 2")); let x: Result<u32, &str> = Ok(2); let y: Result<&str, &str> = Ok("different result type"); assert_eq!(x.and(y), Ok("different result type"));Run
pub fn and_then<U, F: FnOnce(T) -> Result<U, E>>(self, op: F) -> Result<U, E>[src]
Calls op if the result is Ok, otherwise returns the Err value of self.
This function can be used for control flow based on Result values.
Examples
Basic usage:
fn sq(x: u32) -> Result<u32, u32> { Ok(x * x) } fn err(x: u32) -> Result<u32, u32> { Err(x) } assert_eq!(Ok(2).and_then(sq).and_then(sq), Ok(16)); assert_eq!(Ok(2).and_then(sq).and_then(err), Err(4)); assert_eq!(Ok(2).and_then(err).and_then(sq), Err(2)); assert_eq!(Err(3).and_then(sq).and_then(sq), Err(3));Run
pub fn or<F>(self, res: Result<T, F>) -> Result<T, F>[src]
Returns res if the result is Err, otherwise returns the Ok value of self.
Arguments passed to or are eagerly evaluated; if you are passing the
result of a function call, it is recommended to use or_else, which is
lazily evaluated.
Examples
Basic usage:
let x: Result<u32, &str> = Ok(2); let y: Result<u32, &str> = Err("late error"); assert_eq!(x.or(y), Ok(2)); let x: Result<u32, &str> = Err("early error"); let y: Result<u32, &str> = Ok(2); assert_eq!(x.or(y), Ok(2)); let x: Result<u32, &str> = Err("not a 2"); let y: Result<u32, &str> = Err("late error"); assert_eq!(x.or(y), Err("late error")); let x: Result<u32, &str> = Ok(2); let y: Result<u32, &str> = Ok(100); assert_eq!(x.or(y), Ok(2));Run
pub fn or_else<F, O: FnOnce(E) -> Result<T, F>>(self, op: O) -> Result<T, F>[src]
Calls op if the result is Err, otherwise returns the Ok value of self.
This function can be used for control flow based on result values.
Examples
Basic usage:
fn sq(x: u32) -> Result<u32, u32> { Ok(x * x) } fn err(x: u32) -> Result<u32, u32> { Err(x) } assert_eq!(Ok(2).or_else(sq).or_else(sq), Ok(2)); assert_eq!(Ok(2).or_else(err).or_else(sq), Ok(2)); assert_eq!(Err(3).or_else(sq).or_else(err), Ok(9)); assert_eq!(Err(3).or_else(err).or_else(err), Err(3));Run
pub fn unwrap_or(self, default: T) -> T[src]
Returns the contained Ok value or a provided default.
Arguments passed to unwrap_or are eagerly evaluated; if you are passing
the result of a function call, it is recommended to use unwrap_or_else,
which is lazily evaluated.
Examples
Basic usage:
let default = 2; let x: Result<u32, &str> = Ok(9); assert_eq!(x.unwrap_or(default), 9); let x: Result<u32, &str> = Err("error"); assert_eq!(x.unwrap_or(default), default);Run
pub fn unwrap_or_else<F: FnOnce(E) -> T>(self, op: F) -> T[src]
Returns the contained Ok value or computes it from a closure.
Examples
Basic usage:
fn count(x: &str) -> usize { x.len() } assert_eq!(Ok(2).unwrap_or_else(count), 2); assert_eq!(Err("foo").unwrap_or_else(count), 3);Run
pub unsafe fn unwrap_unchecked(self) -> T[src]
🔬 This is a nightly-only experimental API. (option_result_unwrap_unchecked #81383)
newly added
Returns the contained Ok value, consuming the self value,
without checking that the value is not an Err.
Safety
Calling this method on an Err is undefined behavior.
Examples
#![feature(option_result_unwrap_unchecked)] let x: Result<u32, &str> = Ok(2); assert_eq!(unsafe { x.unwrap_unchecked() }, 2);Run
#![feature(option_result_unwrap_unchecked)] let x: Result<u32, &str> = Err("emergency failure"); unsafe { x.unwrap_unchecked(); } // Undefined behavior!Run
pub unsafe fn unwrap_err_unchecked(self) -> E[src]
🔬 This is a nightly-only experimental API. (option_result_unwrap_unchecked #81383)
newly added
Returns the contained Err value, consuming the self value,
without checking that the value is not an Ok.
Safety
Calling this method on an Ok is undefined behavior.
Examples
#![feature(option_result_unwrap_unchecked)] let x: Result<u32, &str> = Ok(2); unsafe { x.unwrap_err_unchecked() }; // Undefined behavior!Run
#![feature(option_result_unwrap_unchecked)] let x: Result<u32, &str> = Err("emergency failure"); assert_eq!(unsafe { x.unwrap_err_unchecked() }, "emergency failure");Run
impl<T: Copy, E> Result<&T, E>[src]
impl<T: Copy, E> Result<&T, E>[src]impl<T: Copy, E> Result<&mut T, E>[src]
impl<T: Copy, E> Result<&mut T, E>[src]impl<T: Clone, E> Result<&T, E>[src]
impl<T: Clone, E> Result<&T, E>[src]impl<T: Clone, E> Result<&mut T, E>[src]
impl<T: Clone, E> Result<&mut T, E>[src]impl<T, E: Debug> Result<T, E>[src]
impl<T, E: Debug> Result<T, E>[src]pub fn expect(self, msg: &str) -> T1.4.0[src]
Returns the contained Ok value, consuming the self value.
Panics
Panics if the value is an Err, with a panic message including the
passed message, and the content of the Err.
Examples
Basic usage:
let x: Result<u32, &str> = Err("emergency failure"); x.expect("Testing expect"); // panics with `Testing expect: emergency failure`Run
pub fn unwrap(self) -> T[src]
Returns the contained Ok value, consuming the self value.
Because this function may panic, its use is generally discouraged.
Instead, prefer to use pattern matching and handle the Err
case explicitly, or call unwrap_or, unwrap_or_else, or
unwrap_or_default.
Panics
Panics if the value is an Err, with a panic message provided by the
Err’s value.
Examples
Basic usage:
let x: Result<u32, &str> = Ok(2); assert_eq!(x.unwrap(), 2);Run
let x: Result<u32, &str> = Err("emergency failure"); x.unwrap(); // panics with `emergency failure`Run
impl<T: Debug, E> Result<T, E>[src]
impl<T: Debug, E> Result<T, E>[src]pub fn expect_err(self, msg: &str) -> E1.17.0[src]
Returns the contained Err value, consuming the self value.
Panics
Panics if the value is an Ok, with a panic message including the
passed message, and the content of the Ok.
Examples
Basic usage:
let x: Result<u32, &str> = Ok(10); x.expect_err("Testing expect_err"); // panics with `Testing expect_err: 10`Run
pub fn unwrap_err(self) -> E[src]
Returns the contained Err value, consuming the self value.
Panics
Panics if the value is an Ok, with a custom panic message provided
by the Ok’s value.
Examples
let x: Result<u32, &str> = Ok(2); x.unwrap_err(); // panics with `2`Run
let x: Result<u32, &str> = Err("emergency failure"); assert_eq!(x.unwrap_err(), "emergency failure");Run
impl<T: Default, E> Result<T, E>[src]
impl<T: Default, E> Result<T, E>[src]pub fn unwrap_or_default(self) -> T1.16.0[src]
Returns the contained Ok value or a default
Consumes the self argument then, if Ok, returns the contained
value, otherwise if Err, returns the default value for that
type.
Examples
Converts a string to an integer, turning poorly-formed strings
into 0 (the default value for integers). parse converts
a string to any other type that implements FromStr, returning an
Err on error.
let good_year_from_input = "1909"; let bad_year_from_input = "190blarg"; let good_year = good_year_from_input.parse().unwrap_or_default(); let bad_year = bad_year_from_input.parse().unwrap_or_default(); assert_eq!(1909, good_year); assert_eq!(0, bad_year);Run
impl<T, E: Into<!>> Result<T, E>[src]
impl<T, E: Into<!>> Result<T, E>[src]pub fn into_ok(self) -> T[src]
🔬 This is a nightly-only experimental API. (unwrap_infallible #61695)
newly added
Returns the contained Ok value, but never panics.
Unlike unwrap, this method is known to never panic on the
result types it is implemented for. Therefore, it can be used
instead of unwrap as a maintainability safeguard that will fail
to compile if the error type of the Result is later changed
to an error that can actually occur.
Examples
Basic usage:
fn only_good_news() -> Result<String, !> { Ok("this is fine".into()) } let s: String = only_good_news().into_ok(); println!("{}", s);Run
impl<T: Into<!>, E> Result<T, E>[src]
impl<T: Into<!>, E> Result<T, E>[src]pub fn into_err(self) -> E[src]
🔬 This is a nightly-only experimental API. (unwrap_infallible #61695)
newly added
Returns the contained Err value, but never panics.
Unlike unwrap_err, this method is known to never panic on the
result types it is implemented for. Therefore, it can be used
instead of unwrap_err as a maintainability safeguard that will fail
to compile if the ok type of the Result is later changed
to a type that can actually occur.
Examples
Basic usage:
fn only_bad_news() -> Result<!, String> { Err("Oops, it failed".into()) } let error: String = only_bad_news().into_err(); println!("{}", error);Run
impl<T: Deref, E> Result<T, E>[src]
impl<T: Deref, E> Result<T, E>[src]pub fn as_deref(&self) -> Result<&T::Target, &E>1.47.0[src]
Converts from Result<T, E> (or &Result<T, E>) to Result<&<T as Deref>::Target, &E>.
Coerces the Ok variant of the original Result via Deref
and returns the new Result.
Examples
let x: Result<String, u32> = Ok("hello".to_string()); let y: Result<&str, &u32> = Ok("hello"); assert_eq!(x.as_deref(), y); let x: Result<String, u32> = Err(42); let y: Result<&str, &u32> = Err(&42); assert_eq!(x.as_deref(), y);Run
impl<T: DerefMut, E> Result<T, E>[src]
impl<T: DerefMut, E> Result<T, E>[src]pub fn as_deref_mut(&mut self) -> Result<&mut T::Target, &mut E>1.47.0[src]
Converts from Result<T, E> (or &mut Result<T, E>) to Result<&mut <T as DerefMut>::Target, &mut E>.
Coerces the Ok variant of the original Result via DerefMut
and returns the new Result.
Examples
let mut s = "HELLO".to_string(); let mut x: Result<String, u32> = Ok("hello".to_string()); let y: Result<&mut str, &mut u32> = Ok(&mut s); assert_eq!(x.as_deref_mut().map(|x| { x.make_ascii_uppercase(); x }), y); let mut i = 42; let mut x: Result<String, u32> = Err(42); let y: Result<&mut str, &mut u32> = Err(&mut i); assert_eq!(x.as_deref_mut().map(|x| { x.make_ascii_uppercase(); x }), y);Run
impl<T, E> Result<Option<T>, E>[src]
impl<T, E> Result<Option<T>, E>[src]pub fn transpose(self) -> Option<Result<T, E>>1.33.0[src]
Transposes a Result of an Option into an Option of a Result.
Ok(None) will be mapped to None.
Ok(Some(_)) and Err(_) will be mapped to Some(Ok(_)) and Some(Err(_)).
Examples
#[derive(Debug, Eq, PartialEq)] struct SomeErr; let x: Result<Option<i32>, SomeErr> = Ok(Some(5)); let y: Option<Result<i32, SomeErr>> = Some(Ok(5)); assert_eq!(x.transpose(), y);Run
impl<T, E> Result<Result<T, E>, E>[src]
impl<T, E> Result<Result<T, E>, E>[src]pub fn flatten(self) -> Result<T, E>[src]
Converts from Result<Result<T, E>, E> to Result<T, E>
Examples
Basic usage:
#![feature(result_flattening)] let x: Result<Result<&'static str, u32>, u32> = Ok(Ok("hello")); assert_eq!(Ok("hello"), x.flatten()); let x: Result<Result<&'static str, u32>, u32> = Ok(Err(6)); assert_eq!(Err(6), x.flatten()); let x: Result<Result<&'static str, u32>, u32> = Err(6); assert_eq!(Err(6), x.flatten());Run
Flattening only removes one level of nesting at a time:
#![feature(result_flattening)] let x: Result<Result<Result<&'static str, u32>, u32>, u32> = Ok(Ok(Ok("hello"))); assert_eq!(Ok(Ok("hello")), x.flatten()); assert_eq!(Ok("hello"), x.flatten().flatten());Run
impl<T> Result<T, T>[src]
impl<T> Result<T, T>[src]pub const fn into_ok_or_err(self) -> T[src]
🔬 This is a nightly-only experimental API. (result_into_ok_or_err #82223)
newly added
Returns the Ok value if self is Ok, and the Err value if
self is Err.
In other words, this function returns the value (the T) of a
Result<T, T>, regardless of whether or not that result is Ok or
Err.
This can be useful in conjunction with APIs such as
Atomic*::compare_exchange, or slice::binary_search, but only in
cases where you don’t care if the result was Ok or not.
Examples
#![feature(result_into_ok_or_err)] let ok: Result<u32, u32> = Ok(3); let err: Result<u32, u32> = Err(4); assert_eq!(ok.into_ok_or_err(), 3); assert_eq!(err.into_ok_or_err(), 4);Run
Trait Implementations
impl<T: Clone, E: Clone> Clone for Result<T, E>[src]
impl<T: Clone, E: Clone> Clone for Result<T, E>[src]fn clone(&self) -> Self[src]
fn clone_from(&mut self, source: &Self)[src]
impl<A, E, V: FromIterator<A>> FromIterator<Result<A, E>> for Result<V, E>[src]
impl<A, E, V: FromIterator<A>> FromIterator<Result<A, E>> for Result<V, E>[src]fn from_iter<I: IntoIterator<Item = Result<A, E>>>(iter: I) -> Result<V, E>[src]
Takes each element in the Iterator: if it is an Err, no further
elements are taken, and the Err is returned. Should no Err occur, a
container with the values of each Result is returned.
Here is an example which increments every integer in a vector, checking for overflow:
let v = vec![1, 2]; let res: Result<Vec<u32>, &'static str> = v.iter().map(|x: &u32| x.checked_add(1).ok_or("Overflow!") ).collect(); assert_eq!(res, Ok(vec![2, 3]));Run
Here is another example that tries to subtract one from another list of integers, this time checking for underflow:
let v = vec![1, 2, 0]; let res: Result<Vec<u32>, &'static str> = v.iter().map(|x: &u32| x.checked_sub(1).ok_or("Underflow!") ).collect(); assert_eq!(res, Err("Underflow!"));Run
Here is a variation on the previous example, showing that no
further elements are taken from iter after the first Err.
let v = vec![3, 2, 1, 10]; let mut shared = 0; let res: Result<Vec<u32>, &'static str> = v.iter().map(|x: &u32| { shared += x; x.checked_sub(2).ok_or("Underflow!") }).collect(); assert_eq!(res, Err("Underflow!")); assert_eq!(shared, 6);Run
Since the third element caused an underflow, no further elements were taken,
so the final value of shared is 6 (= 3 + 2 + 1), not 16.
impl<T, E, F: From<E>> FromResidual<Result<Infallible, E>> for Result<T, F>[src]
impl<T, E, F: From<E>> FromResidual<Result<Infallible, E>> for Result<T, F>[src]fn from_residual(residual: Result<Infallible, E>) -> Self[src]
impl<T, E, F: From<E>> FromResidual<Result<Infallible, E>> for Poll<Result<T, F>>[src]
impl<T, E, F: From<E>> FromResidual<Result<Infallible, E>> for Poll<Result<T, F>>[src]fn from_residual(x: Result<Infallible, E>) -> Self[src]
impl<T, E, F: From<E>> FromResidual<Result<Infallible, E>> for Poll<Option<Result<T, F>>>[src]
impl<T, E, F: From<E>> FromResidual<Result<Infallible, E>> for Poll<Option<Result<T, F>>>[src]fn from_residual(x: Result<Infallible, E>) -> Self[src]
impl<T, E> IntoIterator for Result<T, E>[src]
impl<T, E> IntoIterator for Result<T, E>[src]type Item = T
The type of the elements being iterated over.
type IntoIter = IntoIter<T>
Which kind of iterator are we turning this into?
fn into_iter(self) -> IntoIter<T>ⓘ[src]
Returns a consuming iterator over the possibly contained value.
The iterator yields one value if the result is Result::Ok, otherwise none.
Examples
Basic usage:
let x: Result<u32, &str> = Ok(5); let v: Vec<u32> = x.into_iter().collect(); assert_eq!(v, [5]); let x: Result<u32, &str> = Err("nothing!"); let v: Vec<u32> = x.into_iter().collect(); assert_eq!(v, []);Run
impl<'a, T, E> IntoIterator for &'a Result<T, E>1.4.0[src]
impl<'a, T, E> IntoIterator for &'a Result<T, E>1.4.0[src]impl<'a, T, E> IntoIterator for &'a mut Result<T, E>1.4.0[src]
impl<'a, T, E> IntoIterator for &'a mut Result<T, E>1.4.0[src]impl<T: PartialOrd, E: PartialOrd> PartialOrd<Result<T, E>> for Result<T, E>[src]
impl<T: PartialOrd, E: PartialOrd> PartialOrd<Result<T, E>> for Result<T, E>[src]impl<T, U, E> Sum<Result<U, E>> for Result<T, E> where
T: Sum<U>, 1.16.0[src]
impl<T, U, E> Sum<Result<U, E>> for Result<T, E> where
T: Sum<U>, 1.16.0[src]fn sum<I>(iter: I) -> Result<T, E> where
I: Iterator<Item = Result<U, E>>, [src]
I: Iterator<Item = Result<U, E>>,
Takes each element in the Iterator: if it is an Err, no further
elements are taken, and the Err is returned. Should no Err
occur, the sum of all elements is returned.
Examples
This sums up every integer in a vector, rejecting the sum if a negative element is encountered:
let v = vec![1, 2]; let res: Result<i32, &'static str> = v.iter().map(|&x: &i32| if x < 0 { Err("Negative element found") } else { Ok(x) } ).sum(); assert_eq!(res, Ok(3));Run
impl<T, E> Try for Result<T, E>[src]
impl<T, E> Try for Result<T, E>[src]type Ok = T
The type of this value when viewed as successful.
type Error = E
The type of this value when viewed as failed.
fn into_result(self) -> Self[src]
fn from_ok(v: T) -> Self[src]
fn from_error(v: E) -> Self[src]
impl<T, E> Try for Result<T, E>[src]
impl<T, E> Try for Result<T, E>[src]type Output = T
The type of the value produced by ? when not short-circuiting.
type Residual = Result<Infallible, E>
The type of the value passed to FromResidual::from_residual
as part of ? when short-circuiting. Read more
fn from_output(output: Self::Output) -> Self[src]
fn branch(self) -> ControlFlow<Self::Residual, Self::Output>[src]
impl<T: Copy, E: Copy> Copy for Result<T, E>[src]
impl<T: Eq, E: Eq> Eq for Result<T, E>[src]
impl<T, E> StructuralEq for Result<T, E>[src]
impl<T, E> StructuralPartialEq for Result<T, E>[src]
Auto Trait Implementations
impl<T, E> Send for Result<T, E> where
E: Send,
T: Send,
E: Send,
T: Send,
impl<T, E> Sync for Result<T, E> where
E: Sync,
T: Sync,
E: Sync,
T: Sync,
impl<T, E> Unpin for Result<T, E> where
E: Unpin,
T: Unpin,
E: Unpin,
T: Unpin,