Enum ListenerSite 

pub enum ListenerSite {
    Action {
        component: Symbol,
        action: Symbol,
        argc: usize,
        key: Option<Symbol>,
        carries_value: bool,
        once: Option<Symbol>,
    },
    Bind {
        component: Symbol,
        field: Symbol,
        checked: bool,
    },
    DefaultToggle {
        component: Symbol,
        field: Symbol,
        radio: bool,
    },
    CallbackProp {
        component: Symbol,
        prop: Symbol,
        argc: usize,
        key: Option<Symbol>,
        once: Option<Symbol>,
    },
    ScrollNear {
        component: Symbol,
        action: Symbol,
    },
}

One attached listener, as the dispatcher needs to call it back.

★ IT CARRIES WHAT TO CALL, NOT A CLOSURE. A module cannot hold a listener closure on the browser tier — Map of Text to fn(…) is refused by that backend (“unsupported indirect call”), measured rather than assumed. But the dispatcher never needed the closure: it needs to know WHICH handler and FOR WHICH INSTANCE, and both of those are data. The closure stays where it belongs, on the element, for the browser to call; this is the parallel record a driving verb resolves through.

Variants

Action

on-<event>={action} and When "<sel>" is <event>: — run that action’s turn.

key is the KEY MODIFIER this listener waits for (on-keydown.enter → enter), or None for a handler that answers any press. It is compared case-insensitively against the key the dispatch carries, because a browser reports KeyboardEvent.key as "Enter" while the author writes .enter — the reason the two ends meet at all.

Fields

component: Symbol

action: Symbol

argc: usize

key: Option<Symbol>

carries_value: bool

Whether the handler’s LAST parameter is what the event CARRIED rather than something captured where it was rendered. A dropped file’s name is not state and not a prop — it arrives with the event — so the arm reads the dispatcher’s value slot for it.

once: Option<Symbol>

For an on-<event>.once handler, the render’s local holding the listener’s identity (see once_spent_binding); the registration records it against the listener key and the arm spends it.

Bind

bind={field} — store the delivered value, then repaint.

Fields

component: Symbol

field: Symbol

checked: bool

DefaultToggle

A click on a bound checkbox or radio. Not a listener the page wrote: it is the BROWSER’s default action, which happens before any handler runs, and an in-process host performs it itself (page_host’s Driver::toggle). Registered so the node-keyed lookup finds it like any other.

Fields

component: Symbol

field: Symbol

radio: bool

CallbackProp

on-<event>={<callbackProp>} — a component’s own element calling a callback it was HANDED rather than one of its own actions (docs/frontend.md’s “Passing actions down”). The arm calls the prop’s trampoline (Parser::callback_trampoline) for the registering instance, with the argc arguments the render recorded; key is the key modifier, as on Self::Action.

Fields

component: Symbol

prop: Symbol

argc: usize

key: Option<Symbol>

once: Option<Symbol>

ScrollNear

A scroll the page heard where When the user scrolls to the bottom: waits: the arm asks the geometry how far the scrolled node is from its end, and runs the handler’s turn only within 32px of it — the threshold is compiled LOGOS, the host only measures.

Fields

component: Symbol

action: Symbol

Trait Implementations

impl Clone for ListenerSite

fn clone(&self) -> ListenerSite

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.