Callback Bus¶

Animated GIF showing Glyph callback bus priority order and event dispatch.

Glyph includes a callback bus modeled after Feather-style callback semantics.

Runtime API¶

local off = ui.on("beforeUpdate", function(dt)
  -- work
end, {
  priority = 10,
})

off()

Dispatch manually:

ui.dispatch("event", "custom", payload)

Semantics¶

Only supported callback names can be registered.
Unsupported names error.
Higher-priority callbacks run first.
Registration order breaks priority ties.
The unregister closure is idempotent.
Dispatch uses a snapshot, so callbacks may register/unregister during dispatch safely.
Entries have active flags internally.

Runtime Callback Names¶

beforeUpdate
afterUpdate
beforeRender
afterRender
layout
audio
accessibility
feedback
focusChanged
hoverChanged
event

Component-Local Buses¶

Components can own local callback buses through node props when advanced widgets need local event systems. Prefer simple props for common widgets; use local buses only for complex reusable controls.