Crate drying_paint
source · [−]Expand description
The name ‘drying_paint’ comes from the expression “watching paint dry”. This module provides a system to “watch” some values for changes and run code whenever they change.
use std::{rc::Rc, cell::RefCell};
use drying_paint::{Watcher, Watched, WatcherInit, WatchContext};
// define a type to hold data
struct Content {
dest: i32,
source: Watched<i32>,
}
// define Watcher trait for the type
impl Watcher<'static> for Content {
fn init(mut init: impl WatcherInit<'static, Self>) {
// set up a callback that will be re-run when
// the Watched data changes
init.watch(|root| {
root.dest = *root.source;
});
}
}
// instantiate the content
let content = Rc::new(RefCell::new(Content {
dest: 0,
source: Watched::new(37),
}));
let weak = Rc::downgrade(&content);
// create the Context
let mut ctx = WatchContext::new();
// dest was 0 when instantiated
assert_eq!(content.borrow().dest, 0);
// after adding the watcher, the callback has run (once)
ctx.add_watcher(&weak);
assert_eq!(content.borrow().dest, 37);
// we can change the "watched" value
*content.borrow_mut().source = 43;
assert_eq!(content.borrow().dest, 37);
// and it will be updated when we call
// update on the context
ctx.update();
assert_eq!(content.borrow().dest, 43);Structs
A type which can be used from another thread to trigger watch functions watching an AtomicWatchedMeta.
SyncWatchedMeta is like WatchedMeta, however allows you to create a trigger which may be sent to other threads.
This represents some value which will be interesting to watch. Watcher functions that reference this value will be re-run when this value changes.
A Watched value which provides interior mutability. This provides correct
behavior (triggering watch functions when changed) where Watched<Cell<T>>
would not, and should be slightly more performant than
RefCell<Watched<T>>.
A Watched value which provides interior mutability. This provides correct
behavior (triggering watch functions when changed) where Watched<Cell<T>>
would not, and should be slightly more performant than
RefCell<Watched<T>>.
This represents some value which will be interesting to watch. Watcher functions that reference this value will be re-run when this value changes.
This provides the basic functionality behind watched values. You can use it to provide functionality using the watch system for cases where Watched and WatchedEvent are not appropriate.
The sender half of a watched channel.