Feature Request: Allow named slots to be reactive

[eric-g-97477]

I have a playground.

According to https://github.com/orgs/vuejs/discussions/6096, the default slot is reactive. A watcher can be setup which will trigger when they change.

watch( () > slots.default(), () => { /* do something */ })

However, this does not work with named slots.

I tried writing:

watch( () => slots.foo?.(), () => {
  updateShowSplitter()
})

but when the foo slot appears or disappears, the watch is not triggered.

There is at least one workaround that Burrito provided on the discord channel.
https://discord.com/channels/325477692906536972/568340117052456970/1301267865386618952

It involved creating a composable which used onBeforeUpdate to watch for changes and provide reactivity.

const useSlotsComputed = (getter) => {
  const slots = useSlots()

  const value = ref(getter(slots))

  onBeforeUpdate(() => {
    value.value = getter(slots)
  })

  return value
}

I assume this is the only / best solution. However, I am always interested in learning about alternative solutions.

My preference would be to use a watcher which would be triggered as the named slots change.