Some core types use events. These events can be used to run a function when a certain trigger happens on a specific object.

To trigger an event on an object, call this event from the chosen object. Events are designed to be triggered by their owner, and listened to by other objects.

For example, if you create a new component type extending COMP_WORKPLACE, you can do the following in one of this type's function:

myCustomWorkplace.registerVillager = function(villager)
    ...
    self.ON_ASSIGNED_WORKER_CHANGED(villager)
    ...
end

When you create a custom type, objects of this type can listen to event triggers, and run functions when those events are triggered. For this, you use three new event-specific functions in the event table.

Register to an event triggered on a specific target object.

void event.register(target, objectEvent, callback)

local compMainGameLoop = getLevel():find("COMP_MAIN_GAME_LOOP")
event.register(self, compMainGameLoop.ON_NEW_DAY, function()
	myMod:log("New day!")
end)
 
local parentBuilding = getOwner():findFirstObjectWithComponentUp("COMP_BUILDING")
event.register(self, parentBuilding.ON_CUSTOM_NAME_CHANGED, function(newName)
	myMod:log("Building name changed to " .. newName)
end)

Stops listening to an event registered on a specific target object.

void event.unregister(target, objectEvent)

local compMainGameLoop = getLevel():find("COMP_MAIN_GAME_LOOP")
event.unregister(self, compMainGameLoop.ON_NEW_DAY)

Stops listening to all events registered on the target object

void event.clear(target)