core::task::Poll - Rust
Description: API documentation for the Rust `Poll` enum in crate `core`.
Keywords: rust, rustlang, rust-lang, Poll

# 1.36.0[−][src]Enum core::task::Poll

    #[must_use =
      "this `Poll` may be a `Pending` variant, which should be handled"]pub enum Poll<T> {
        Ready(T),
        Pending,
    }

Indicates whether a value is available or if the current task has been scheduled to receive a wakeup instead.

## Variants

`Ready(T)`

Represents that a value is immediately ready.

`Pending`

Represents that a value is not ready yet.

When a function returns `Pending`, the function must also ensure that the current task is scheduled to be awoken when progress can be made.

## Implementations

### `impl<T> Poll<T>`[src]

#### `pub fn map<U, F>(self, f: F) -> Poll<U> where
F: FnOnce(T) -> U,` [src]

Changes the ready value of this `Poll` with the closure provided.

#### `pub fn is_ready(&self) -> bool`[src]

Returns `true` if this is `Poll::Ready`

#### `pub fn is_pending(&self) -> bool`[src]

Returns `true` if this is `Poll::Pending`

### `impl<T, E> Poll<Result<T, E>>`[src]

#### `pub fn map_ok<U, F>(self, f: F) -> Poll<Result<U, E>> where
F: FnOnce(T) -> U,` [src]

Changes the success value of this `Poll` with the closure provided.

#### `pub fn map_err<U, F>(self, f: F) -> Poll<Result<T, U>> where
F: FnOnce(E) -> U,` [src]

Changes the error value of this `Poll` with the closure provided.

### `impl<T, E> Poll<Option<Result<T, E>>>`[src]

#### `pub fn map_ok<U, F>(self, f: F) -> Poll<Option<Result<U, E>>> where
F: FnOnce(T) -> U,` [src]

🔬 This is a nightly-only experimental API. (`poll_map` #63514)

Changes the success value of this `Poll` with the closure provided.

#### `pub fn map_err<U, F>(self, f: F) -> Poll<Option<Result<T, U>>> where
F: FnOnce(E) -> U,` [src]

🔬 This is a nightly-only experimental API. (`poll_map` #63514)

Changes the error value of this `Poll` with the closure provided.

## Trait Implementations

### `impl<T: Clone> Clone for Poll<T>`[src]

#### `fn clone(&self) -> Poll<T>`[src]

Returns a copy of the value. Read more

#### `fn clone_from(&mut self, source: &Self)`1.0.0[src]

Performs copy-assignment from `source`. Read more

### `impl<T: Copy> Copy for Poll<T>`[src]

### `impl<T: Debug> Debug for Poll<T>`[src]

#### `fn fmt(&self, f: &mut Formatter) -> Result`[src]

Formats the value using the given formatter. Read more

### `impl<T: Eq> Eq for Poll<T>`[src]

### `impl<T> From<T> for Poll<T>`[src]

#### `fn from(t: T) -> Poll<T>`[src]

Performs the conversion.

### `impl<T: Hash> Hash for Poll<T>`[src]

#### `fn hash<__H: Hasher>(&self, state: &mut __H)`[src]

Feeds this value into the given [`Hasher`]. Read more

#### `fn hash_slice<H: Hasher>(data: &[Self], state: &mut H) where
Self: Sized,` 1.3.0[src]

Feeds a slice of this type into the given [`Hasher`]. Read more

### `impl<T: Ord> Ord for Poll<T>`[src]

#### `fn cmp(&self, other: &Poll<T>) -> Ordering`[src]

This method returns an `Ordering` between `self` and `other`. Read more

#### `#[must_use]fn max(self, other: Self) -> Self where
Self: Sized,` 1.21.0[src]

Compares and returns the maximum of two values. Read more

#### `#[must_use]fn min(self, other: Self) -> Self where
Self: Sized,` 1.21.0[src]

Compares and returns the minimum of two values. Read more

#### `#[must_use]fn clamp(self, min: Self, max: Self) -> Self where
Self: Sized,` [src]

🔬 This is a nightly-only experimental API. (`clamp` #44095)

Restrict a value to a certain interval. Read more

### `impl<T: PartialEq> PartialEq<Poll<T>> for Poll<T>`[src]

#### `fn eq(&self, other: &Poll<T>) -> bool`[src]

This method tests for `self` and `other` values to be equal, and is used by `==`. Read more

#### `fn ne(&self, other: &Poll<T>) -> bool`[src]

This method tests for `!=`.

### `impl<T: PartialOrd> PartialOrd<Poll<T>> for Poll<T>`[src]

#### `fn partial_cmp(&self, other: &Poll<T>) -> Option<Ordering>`[src]

This method returns an ordering between `self` and `other` values if one exists. Read more

#### `fn lt(&self, other: &Poll<T>) -> bool`[src]

This method tests less than (for `self` and `other`) and is used by the `<` operator. Read more

#### `fn le(&self, other: &Poll<T>) -> bool`[src]

This method tests less than or equal to (for `self` and `other`) and is used by the `<=` operator. Read more

#### `fn gt(&self, other: &Poll<T>) -> bool`[src]

This method tests greater than (for `self` and `other`) and is used by the `>` operator. Read more

#### `fn ge(&self, other: &Poll<T>) -> bool`[src]

This method tests greater than or equal to (for `self` and `other`) and is used by the `>=` operator. Read more

### `impl<T> StructuralEq for Poll<T>`[src]

### `impl<T> StructuralPartialEq for Poll<T>`[src]

### `impl<T, E> Try for Poll<Result<T, E>>`[src]

#### `type Ok = Poll<T>`

🔬 This is a nightly-only experimental API. (`try_trait` #42327)

The type of this value when viewed as successful.

#### `type Error = E`

🔬 This is a nightly-only experimental API. (`try_trait` #42327)

The type of this value when viewed as failed.

#### `fn into_result(self) -> Result<Self::Ok, Self::Error>`[src]

🔬 This is a nightly-only experimental API. (`try_trait` #42327)

Applies the "?" operator. A return of `Ok(t)` means that the execution should continue normally, and the result of `?` is the value `t`. A return of `Err(e)` means that execution should branch to the innermost enclosing `catch`, or return from the function. Read more

#### `fn from_error(e: Self::Error) -> Self`[src]

🔬 This is a nightly-only experimental API. (`try_trait` #42327)

Wrap an error value to construct the composite result. For example, `Result::Err(x)` and `Result::from_error(x)` are equivalent. Read more

#### `fn from_ok(x: Self::Ok) -> Self`[src]

🔬 This is a nightly-only experimental API. (`try_trait` #42327)

Wrap an OK value to construct the composite result. For example, `Result::Ok(x)` and `Result::from_ok(x)` are equivalent. Read more

### `impl<T, E> Try for Poll<Option<Result<T, E>>>`[src]

#### `type Ok = Poll<Option<T>>`

🔬 This is a nightly-only experimental API. (`try_trait` #42327)

The type of this value when viewed as successful.

#### `type Error = E`

🔬 This is a nightly-only experimental API. (`try_trait` #42327)

The type of this value when viewed as failed.

#### `fn into_result(self) -> Result<Self::Ok, Self::Error>`[src]

🔬 This is a nightly-only experimental API. (`try_trait` #42327)

Applies the "?" operator. A return of `Ok(t)` means that the execution should continue normally, and the result of `?` is the value `t`. A return of `Err(e)` means that execution should branch to the innermost enclosing `catch`, or return from the function. Read more

#### `fn from_error(e: Self::Error) -> Self`[src]

🔬 This is a nightly-only experimental API. (`try_trait` #42327)

Wrap an error value to construct the composite result. For example, `Result::Err(x)` and `Result::from_error(x)` are equivalent. Read more

#### `fn from_ok(x: Self::Ok) -> Self`[src]

🔬 This is a nightly-only experimental API. (`try_trait` #42327)

Wrap an OK value to construct the composite result. For example, `Result::Ok(x)` and `Result::from_ok(x)` are equivalent. Read more

## Auto Trait Implementations

### `impl<T> Send for Poll<T> where
T: Send,`

### `impl<T> Sync for Poll<T> where
T: Sync,`

### `impl<T> Unpin for Poll<T> where
T: Unpin,`

## Blanket Implementations

### `impl<T> Any for T where
T: 'static + ?Sized,` [src]

#### `fn type_id(&Self) -> TypeId`[src]

Gets the `TypeId` of `self`. Read more

### `impl<T> Borrow<T> for T where
T: ?Sized,` [src]

#### `fn borrow(&Self) -> &T`[src]

Immutably borrows from an owned value. Read more

### `impl<T> BorrowMut<T> for T where
T: ?Sized,` [src]

#### `fn borrow_mut(&mut Self) -> &mut T`[src]

Mutably borrows from an owned value. Read more

### `impl<T> From<!> for T`[src]

#### `fn from(!) -> T`[src]

Performs the conversion.

### `impl<T> From<T> for T`[src]

#### `fn from(T) -> T`[src]

Performs the conversion.

### `impl<T, U> Into<U> for T where
U: From<T>,` [src]

#### `fn into(Self) -> U`[src]

Performs the conversion.

### `impl<T, U> TryFrom<U> for T where
U: Into<T>,` [src]

#### `type Error = Infallible`

The type returned in the event of a conversion error.

#### `fn try_from(U) -> Result<T, <T as TryFrom<U>>::Error>`[src]

Performs the conversion.

### `impl<T, U> TryInto<U> for T where
U: TryFrom<T>,` [src]

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

The type returned in the event of a conversion error.

#### `fn try_into(Self) -> Result<U, <U as TryFrom<T>>::Error>`[src]

Performs the conversion.