Quasar codegen idea

current.rs

// Current example without codegen
impl Component for TodoList {
    fn onload(view: &View<Self>) {
        view.query("button").expect("missing todo list button")
            .on(EventType::Click, |mut evt| {
                match evt.app.query("#message") {
                    Some(node) => {
                        let item = TodoItem::new(&node.get("value"));
                        evt.binding.data_mut().items.push(item);
                    }
                    None => println!("Query #message returned nothing.")
                }
            });

        view.on_each(EventType::Change, ".todo-item input", |mut evt| {
            let state = evt.target.checked();
            let mut item_list = evt.binding.data_mut();
            item_list.items[evt.index].complete = state;
        });
    }
}

goal.rs

// Using codegen to get closer to this
//
// Basic idea is to let users specify what their handlers want
// and generate the code to call it with the data required
//
// Examples:
//   &self     -> evt.binding.data()
//   &mut self -> evt.binding.data_mut()
//   &item     -> evt.binding.data().items[evt.index]
//   &mut item -> evt.binding.data_mut().items[evt.index]
//   Document  -> evt.app
//
// Also it becomes possible to have different return type, e.g. () or Result<(), E>
//
// 
impl TodoList {
    #[on(event="click", el="button")]
    fn add_item(&mut self, document: Document) -> Result<()> {
        let message = document.query("#message")
            .ok_or_else(|| bail!("#message element not found")?;
        let item = TodoItem::new(message.get("value"));
        self.items.push(item);
        Ok(())
    }

    #[on(event="change", el=".todo-item input")]
    fn toggle_check(evt: Event, item: &mut TodoItem) {
        item.complete = evt.target.checked();
    }
}