Before and After Events

World:emit can be wrapped. beforeEmit runs before listeners; afterEmit runs after. Assign them on the World instance. This is middleware: log, profile, swallow draw while paused — not something a gameplay System should need.

The hooks

function world:beforeEmit (systemName, eventName, listeners, ...)
  self._t = love.timer.getTime()
end

function world:afterEmit (systemName, eventName, listeners, ...)
  local dt = love.timer.getTime() - self._t
  if dt > 0.002 then
    print(eventName, dt)
  end
end

systemName is set when the emit was targeted ("Movement.update"); otherwise it is nil. eventName is update in both cases. listeners is the internal list, or nil if nobody registered.

Return a truthy value from beforeEmit to skip listeners and afterEmit for that emit:

function world:beforeEmit (systemName, eventName)
  if eventName == "draw" and self:getResource("paused") then
    return true
  end
end

That is a blunt pause. Prefer setEnabled when you only want some Systems quiet; swallow at the World when nothing should hear draw.

Nested emits

Emits you fire from inside beforeEmit or afterEmit do not re-enter the hooks. Concord sets that guard so a logger that emits "log" cannot recurse. These hooks wrap every emit, targeted or not.

See also