# tokio::sync::watch::Receiver - Rust
API documentation for the Rust `Receiver` struct in crate `tokio`.
Keywords: rust, rustlang, rust-lang, Receiver

# Struct tokio::sync::watch::Receiver [−] [src]

    pub struct Receiver<T> { /* fields omitted */ }

Receives values from the associated `Sender`.

Instances are created by the `channel` function.

To turn this receiver into a `Stream`, you can use the `WatchStream` wrapper.

## Implementations

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

#### `pub fn borrow(&self) -> Ref<'_, T>` [src]

Returns a reference to the most recently sent value

Outstanding borrows hold a read lock. This means that long lived borrows could cause the send half to block. It is recommended to keep the borrow as short lived as possible.

# Examples

    use tokio::sync::watch;

    let (_, rx) = watch::channel("hello");
    assert_eq!(*rx.borrow(), "hello");

#### `pub async fn changed(&mut self) -> Result<(), RecvError>` [src]

Wait for a change notification

Returns when a new value has been sent by the `Sender` since the last time `changed()` was called. When the `Sender` half is dropped, `Err` is returned.

# Examples

    use tokio::sync::watch;

    #[tokio::main]
    async fn main() {
        let (tx, mut rx) = watch::channel("hello");

        tokio::spawn(async move {
            tx.send("goodbye").unwrap();
        });

        assert!(rx.changed().await.is_ok());
        assert_eq!(*rx.borrow(), "goodbye");

        // The `tx` handle has been dropped
        assert!(rx.changed().await.is_err());
    }

## Trait Implementations

### `impl<T> Clone for Receiver<T>` [src]

#### `fn clone(&self) -> Self` [src]

Returns a copy of the value. Read more

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

Performs copy-assignment from `source`. Read more

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

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

Formats the value using the given formatter. Read more

### `impl<T> Drop for Receiver<T>` [src]

#### `fn drop(&mut self)` [src]

Executes the destructor for this type. Read more

## Auto Trait Implementations

### `impl<T> !RefUnwindSafe for Receiver<T>` [src]

### `impl<T> Send for Receiver<T> where
T: Send + Sync,` [src]

### `impl<T> Sync for Receiver<T> where
T: Send + Sync,` [src]

### `impl<T> Unpin for Receiver<T>` [src]

### `impl<T> !UnwindSafe for Receiver<T>` [src]

## Blanket Implementations

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

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

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

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

#### `pub fn borrow(&self) -> &Tⓘ

### Notable traits for &'_ mut F

`impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;`
` [src]

Immutably borrows from an owned value. Read more

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

#### `pub fn borrow_mut(&mut self) -> &mut Tⓘ

### Notable traits for &'_ mut F

`impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;`
` [src]

Mutably borrows from an owned value. Read more

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

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

Performs the conversion.

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

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

Performs the conversion.

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

#### `type Owned = T`

The resulting type after obtaining ownership.

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

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

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

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

recently added

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

### `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.

#### `pub fn try_from(value: 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.

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

Performs the conversion.