Trait Selector 

pub trait Selector<S: GlobalState> {
    type Output;

    // Required method
    fn select(view: ViewHandle<S>) -> Self::Output;
}

A selector that derives a value from a ViewHandle.

Selectors extract and transform data from state so widgets can depend on derived values without coupling to the full state shape.

Example

struct ItemCount;
impl Selector<MyState> for ItemCount {
    type Output = usize;
    fn select(view: ViewHandle<MyState>) -> usize {
        view.state().items.len()
    }
}

// In a widget:
let count: usize = view.select_with::<ItemCount>();

Required Associated Types

type Output

The type produced by the selector.

Required Methods

fn select(view: ViewHandle<S>) -> Self::Output

Extract the value from the given view handle.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors