8 releases
0.3.5 | Jan 15, 2024 |
---|---|
0.3.4 | Jan 12, 2024 |
0.3.3 | Dec 29, 2023 |
0.3.2 | Jan 31, 2022 |
0.1.0 | Oct 11, 2018 |
#246 in Asynchronous
1,095 downloads per month
Used in bui-backend
10KB
58 lines
async-change-tracker
Reactive change notifications using futures.
The ChangeTracker<T>
type wraps an owned value T
. Changes to T
are
done within a function or closure implementing FnOnce(&mut T)
. When this
returns, any changes are sent to listeners using a futures::Stream
.
In slightly more detail, create a ChangeTracker<T>
with
ChangeTracker::new(value: T)
. This
will take ownership of the value of type T
. You can then create a
futures::Stream
(with
get_changes()
) that emits
a tuple (old_value, new_value)
of type (T, T)
upon every change to the
owned value. The value can be changed with the
modify()
method of
ChangeTracker
and read using the as_ref()
method from the AsRef
trait.
Example
In this example, the functionality of ChangeTracker
is shown.
use futures::stream::StreamExt;
// Wrap an integer `with ChangeTracker`
let mut change_tracker = async_change_tracker::ChangeTracker::new( 123 );
// Create an receiver that fires when the value changes. The channel size
// is 1, meaning at most one change can be buffered before backpressure
// is applied.
let rx = change_tracker.get_changes(1);
// In this example take a single change and check that the old and new value
// are correct.
let rx_printer = rx.take(1).for_each(|(old_value, new_value)| {
assert_eq!( old_value, 123);
assert_eq!( new_value, 124);
futures::future::ready(())
});
// Now, check and then change the value.
change_tracker.modify(|mut_ref_value| {
assert_eq!(*mut_ref_value, 123);
*mut_ref_value += 1;
});
// Wait until the stream is done. In this example, the stream ends due to
// the use of `.take(1)` prior to `for_each` above. In normal usage,
// typically the stream would finish for a different reason.
futures::executor::block_on(rx_printer);
// Finally, check that the final value is as expected.
assert!(*change_tracker.as_ref() == 124);
Testing
To test:
cargo test
License: MIT/Apache-2.0
Dependencies
~1–1.2MB
~20K SLoC