Signals

Signals are values with change tracking built in. In practice, this means you create a signal once, bind it to views and modifiers, and then update it as application state changes.

Creating a signal

let count = Signal::new(0);

Signals are Copy, so you can pass them into bindings and callbacks without cloning or borrowing state.

Signals are commonly stored on a model:

pub struct AppData {
    count: Signal<i32>,
}

impl Model for AppData {}

Signals are lightweight handles and are Copy, so you can pass them into bindings and callbacks without cloning or borrowing state.

Where to read and write

• For read patterns (get, with, map, SignalGet), see Reading Signals.
• For write patterns (set, update, set_if_changed, write), see Writing Signals.

Capturing signals in closures

When a closure captures a signal, prefer move:

Binding::new(cx, count, move |cx| {
    if count.get(cx) > 10 {
        Label::new(cx, "Large value");
    }
});

Because signals are Copy, moving a signal into the closure just copies the handle.

See also

• Data binding
• Reading Signals
• Writing Signals
• Derived Signals with Memo
• Derived Signals with map()
• Sync Signals