async-observe 0.1.0

Async single-producer, multi-consumer channel that only retains the last sent value
Documentation 
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<div align="center">
    <h1>async-observe</h1>
    <p>
        Async single-producer, multi-consumer channel that only retains the last sent value
    </p>
    <p>
        <a href="https://crates.io/crates/async"><img src="https://img.shields.io/crates/v/async.svg"></img></a>
        <a href="https://docs.rs/async"><img src="https://docs.rs/async/badge.svg"></img></a>
    </p>
</div>

## Usage

The [`channel`] function creates a pair of [`Sender`] and [`Receiver`]. To create the channel provide its initial value.

Each receiver independently tracks the last observed value. To read the current value, use the receiver's [`observe`] method. To wait for a change, call the async [`changed`] method on the receiver. If the value implements `Clone`, you can also use the [`recv`] method to wait for a change and immediately read the new value.

To update the value, call the sender's [`send`] method. This method is non-async and does not block the current thread - the value is updated immediately. This makes it convenient to send values from both async and synchronous contexts.

[`channel`]: https://docs.rs/async-observe/latest/async-observe/fn.channel.html
[`Sender`]: https://docs.rs/async-observe/latest/async-observe/struct.Sender.html
[`Receiver`]: https://docs.rs/async-observe/latest/async-observe/struct.Receiver.html
[`observe`]: https://docs.rs/async-observe/latest/async-observe/struct.Receiver.html#method.observe
[`changed`]: https://docs.rs/async-observe/latest/async-observe/struct.Receiver.html#method.changed
[`recv`]: https://docs.rs/async-observe/latest/async-observe/struct.Receiver.html#method.recv
[`send`]: https://docs.rs/async-observe/latest/async-observe/struct.Sender.html#method.send

## Examples

This example prints numbers from 0 to 9:

```rust
use {
    futures_lite::future,
    std::{thread, time::Duration},
};

let (tx, mut rx) = async_observe::channel(0);

// Perform computations in another thread
thread::spawn(move || {
    for n in 1..10 {
        thread::sleep(Duration::from_secs(1));

        // Send a new value without blocking the thread.
        // If sending fails, it means the sender was dropped.
        // In that case stop the computation.
        if tx.send(n).is_err() {
            break;
        }
    }
});

// Print the initial value (0)
let n = rx.observe(|n| *n);
println!("{n}");

future::block_on(async {
    // Print the value whenever it changes
    while let Ok(n) = rx.recv().await {
        println!("{n}");
    }
});
```

In this example a new thread is spawned, but you can also use the channel
to update values from a future/async task.

Note that this channel does not have a message queue - it only stores the
latest update. Therefore, it does *not* guarantee that you will observe
every intermediate value. If you need to observe each change, use a
message-queue channel such as [`async-channel`].

[`async-channel`]: https://docs.rs/async-channel/latest/async_channel