Macro define_component 

macro_rules! define_component {
    (
        name: $name:expr,
        state: { $($field:ident : $type:ty = $default:expr),* $(,)? },
        template: $template:expr
        $(, styles: $styles:expr)?
        $(, on_init: $on_init:expr)?
        $(, on_destroy: $on_destroy:expr)?
        $(,)?
    ) => { ... };
}

Define a component with Angular-like syntax.

Example

define_component! {
    name: "my-counter",
    state: { count: i32 = 0 },
    template: |state, ctx| {
        col![
            label!(format!("Count: {}", state.count)),
            button!("+", { ctx.update(|s| s.count += 1); }),
        ]
    },
    styles: r#"
        .counter { padding: 16px; }
    "#,
    on_init: |state| { println!("Init: {}", state.count); },
}