Macro wayland_client::event_created_child

macro_rules! event_created_child {
    ($(@< $( $lt:tt $( : $clt:tt $(+ $dlt:tt )* )? ),+ >)? $selftype:ty, $iface:ty, [$($opcode:pat => ($child_iface:ty, $child_udata:expr)),* $(,)?]) => { ... };
}

Macro used to override Dispatch::event_created_child()

Use this macro inside the Dispatch implementation to override this method, to implement the initialization of the user data for event-created objects. The usage syntax is as follow:

impl Dispatch<WlFoo, FooUserData> for MyState {
    fn event(
        &mut self,
        proxy: &WlFoo,
        event: FooEvent,
        data: &FooUserData,
        connhandle: &mut ConnectionHandle,
        qhandle: &QueueHandle<MyState>
    ) {
        /* ... */
    }

    event_created_child!(MyState, WlFoo, [
    // there can be multiple lines if this interface has multiple object-creating event
        EVT_CREATE_BAR => (WlBar, BarUserData::new()),
    //  ~~~~~~~~~~~~~~     ~~~~~  ~~~~~~~~~~~~~~~~~~
    //    |                  |      |
    //    |                  |      +-- an expression whose evaluation produces the
    //    |                  |          user data value
    //    |                  +-- the type of the newly created object
    //    +-- the opcode of the event that creates a new object, constants for those are
    //        generated alongside the `WlFoo` type in the `wl_foo` module
    ]);
}