Gameplay events

demi.gameplay.events connects Lua gameplay systems through named, queued events. Each queue belongs to its caller. Create one per scene, game, or subsystem; there is no global event bus and no dependency on physics or rendering.

Use

Install from this checkout's development registry:

demi package add demi.gameplay.events@1.0.0 --registry /path/to/DemiEngine/packages

local Events = require("demi.gameplay.events")
local events = Events.new()

local unsubscribe = events:on("door_opened", function(payload)
    print("Opened " .. payload.id)
end)

events:emit("door_opened", {id = "front_door"})
events:flush()
unsubscribe()

emit(name, payload) queues an event; it does not call listeners immediately. flush() dispatches queued events in emission order. Higher listener priorities run first (the optional third argument to on); equal priorities retain registration order. on returns an unsubscribe function.

Events emitted by a listener are processed during the same flush. Avoid cycles that keep emitting indefinitely. Payloads are Lua references, not snapshots; mutating a table before flushing changes what listeners receive. Callback errors propagate to the caller. This is a local gameplay queue, not a network transport or persistent event log.

Development

This package replaces the development-era name demi.gameplay.core. There is no alias package. The Lua import remains demi.gameplay.events. Reinstall dependent packages from the local registry to refresh their manifests and lock hashes.

Run demi package test packages/sources/demi.gameplay.events from the engine root.