Struct drying_paint::Watched

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

This represents some value which will be interesting to watch. Watcher functions that reference this value will be re-run when this value changes.

Methods

impl<T> Watched<T>

pub fn new(value: T) -> Self

Create a new watched value.

impl<T: PartialEq> Watched<T>

pub fn set_if_neq(wrapper: &mut Watched<T>, value: T)

This function provides a way to set a value for a watched value only if is has changed. This is useful for cases where setting a value would otherwise cause an infinite loop.

Examples

The following example uses the watch system to keep two variables in sync. This would normally cause an infinite loop as each update of one would cause the other one to re-evaluate. However using set_if_neq allows it to detect that the value is the same and stop propogating.

#[derive(Default)]
struct KeepBalanced {
    left: Watched<i32>,
    right: Watched<i32>,
}
impl WatcherInit for KeepBalanced {
    fn init(watcher: &mut WatcherMeta<Self>) {
        watcher.watch(|root| {
            Watched::set_if_neq(&mut root.left, *root.right);
        });
        watcher.watch(|root| {
            Watched::set_if_neq(&mut root.right, *root.left);
        });
    }
}
fn main() {
    let mut ctx = WatchContext::new();
    ctx.set_frame_limit(Some(100));
    ctx.with(|| {
        let mut obj = Watcher::<KeepBalanced>::new();
        *obj.data_mut().left = 68;
        WatchContext::update_current();
        assert_eq!(*obj.data().right, 68);
    });
}

Trait Implementations

impl<T: Clone> Clone for Watched<T>

fn clone(&self) -> Watched<T>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<T: Debug> Debug for Watched<T>

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

Formats the value using the given formatter.

impl<T: Default> Default for Watched<T>

fn default() -> Self

Returns the "default value" for a type.

impl<T> Deref for Watched<T>

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &T

Dereferences the value.

impl<T> DerefMut for Watched<T>

fn deref_mut(&mut self) -> &mut T

Mutably dereferences the value.

impl<T: Display> Display for Watched<T>

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

Formats the value using the given formatter.

impl<T: Eq> Eq for Watched<T>

impl<T: Ord> Ord for Watched<T>

fn cmp(&self, other: &Watched<T>) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

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

Restrict a value to a certain interval.

impl<T: PartialEq> PartialEq<Watched<T>> for Watched<T>

fn eq(&self, other: &Watched<T>) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Watched<T>) -> bool

This method tests for !=.

impl<T: PartialOrd> PartialOrd<Watched<T>> for Watched<T>

fn partial_cmp(&self, other: &Watched<T>) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Watched<T>) -> bool

This method tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Watched<T>) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

fn ge(&self, other: &Watched<T>) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

fn gt(&self, other: &Watched<T>) -> bool

This method tests greater than (for self and other) and is used by the > operator.