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

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

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

Sends values to the associated `Receiver`.

Instances are created by the `channel` function.

## Implementations

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

#### `pub fn send(&self, value: T) -> Result<(), SendError<T>>` [src]

Sends a new value via the channel, notifying all receivers.

#### `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 (tx, _) = watch::channel("hello");
    assert_eq!(*tx.borrow(), "hello");

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

Checks if the channel has been closed. This happens when all receivers have dropped.

# Examples

    let (tx, rx) = tokio::sync::watch::channel(());
    assert!(!tx.is_closed());

    drop(rx);
    assert!(tx.is_closed());

#### `pub async fn closed(&self)` [src]

Completes when all receivers have dropped.

This allows the producer to get notified when interest in the produced values is canceled and immediately stop doing work.

# Examples

    use tokio::sync::watch;

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

        tokio::spawn(async move {
            // use `rx`
            drop(rx);
        });

        // Waits for `rx` to drop
        tx.closed().await;
        println!("the `rx` handles dropped")
    }

## Trait Implementations

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

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

Formats the value using the given formatter. Read more

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

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

Executes the destructor for this type. Read more

## Auto Trait Implementations

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

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

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

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

### `impl<T> !UnwindSafe for Sender<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, 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.