Struct Watchable 

pub struct Watchable<T> { /* private fields */ }

A wrapper around a value that notifies Watchers when the value is modified.

Only the most recent value is available to any observer, but the observer is guaranteed to be notified of the most recent value.

Implementations

impl<T: Clone + Eq> Watchable<T>

pub fn new(value: T) -> Self

Creates a Watchable initialized to given value.

pub fn set(&self, value: T) -> Result<T, T>

Sets a new value.

Returns Ok(previous_value) if the value was different from the one set, or returns the provided value back as Err(value) if the value didn’t change.

Watchers are only notified if the value changed.

pub fn watch(&self) -> Direct<T>

Creates a Direct Watcher, allowing the value to be observed, but not modified.

pub fn watch_lazy(&self) -> LazyDirect<T>

where T: Default,

Creates a LazyDirect Watcher, allowing the value to be observed, but not modified.

The LazyDirect watcher does not store the current value, making it smaller. If the watchable is dropped, LazyDirect::get returns T::default.

pub fn weak_watcher(&self) -> WeakWatcher<T>

Creates a WeakWatcher, which is a weak reference to the watchable’s shared state.

It has the size of a single pointer, and can be upgraded to a Direct or LazyDirect.

pub fn get(&self) -> T

Returns the currently stored value.

pub fn has_watchers(&self) -> bool

Returns true when there are any watchers actively listening on changes, or false when all watchers have been dropped or none have been created yet.

Trait Implementations

impl<T> Clone for Watchable<T>

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T: Debug> Debug for Watchable<T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T: Default> Default for Watchable<T>

fn default() -> Watchable<T>

Returns the “default value” for a type.

impl<T> Drop for Watchable<T>

fn drop(&mut self)

Executes the destructor for this type.