# 1.36.0[−][src]Enum std::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.

## Methods

### `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.

## Trait Implementations

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

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

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

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

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

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

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

### `impl<T> Clone for Poll<T> where
T: Clone,` [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, 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<<Poll<Option<Result<T, E>>> as Try>::Ok, <Poll<Option<Result<T, E>>> as Try>::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: <Poll<Option<Result<T, E>>> as Try>::Error
) -> Poll<Option<Result<T, E>>>`[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: <Poll<Option<Result<T, E>>> as Try>::Ok
) -> Poll<Option<Result<T, E>>>`[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<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<<Poll<Result<T, E>> as Try>::Ok, <Poll<Result<T, E>> as Try>::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: <Poll<Result<T, E>> as Try>::Error) -> Poll<Result<T, E>>`[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: <Poll<Result<T, E>> as Try>::Ok) -> Poll<Result<T, E>>`[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> Debug for Poll<T> where
T: Debug,` [src]

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

Formats the value using the given formatter. Read more

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

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

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

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

Compares and returns the maximum of two values. Read more

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

Compares and returns the minimum of two values. Read more

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

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

Restrict a value to a certain interval. Read more

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

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

Performs the conversion.

## Auto Trait Implementations

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

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

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

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

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

## Blanket Implementations

### `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(value: U) -> Result<T, <T as TryFrom<U>>::Error>`[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> From<T> for T`[src]

#### `fn from(t: T) -> T`[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.

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

####
ⓘImportant traits for &'_ mut F

### Important traits for &'_ mut F

`impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<'_, R: Read + ?Sized> Read for &'_ mut Rimpl<'_, W: Write + ?Sized> Write for &'_ mut W`
`fn borrow(&self) -> &T`[src]

Immutably borrows from an owned value. Read more

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

####
ⓘImportant traits for &'_ mut F

### Important traits for &'_ mut F

`impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<'_, R: Read + ?Sized> Read for &'_ mut Rimpl<'_, W: Write + ?Sized> Write for &'_ mut W`
`fn borrow_mut(&mut self) -> &mut T`[src]

Mutably borrows from an owned value. Read more

### `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> ToOwned for T where
T: Clone,` [src]

#### `type Owned = T`

The resulting type after obtaining ownership.

#### `fn to_owned(&self) -> T`[src]

Creates owned data from borrowed data, usually by cloning. Read more

#### `fn clone_into(&self, target: &mut T)`[src]

🔬 This is a nightly-only experimental API. (`toowned_clone_into` #41263)

recently added

Uses borrowed data to replace owned data, usually by cloning. Read more

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