mirror of
https://github.com/Ukendio/jecs.git
synced 2026-02-04 15:15:21 +00:00
40 lines
1.6 KiB
Text
Executable file
40 lines
1.6 KiB
Text
Executable file
--[[
|
|
Component data generally need to adhere to a specific interface, and sometimes
|
|
requires side effects to run upon certain lifetime cycles. In jecs, there are
|
|
hooks which are component traits, that can define the behaviour of a component
|
|
and enforce invariants, but can only be invoked through mutations on the
|
|
component data. You can only configure a single OnAdd, OnRemove and OnChange
|
|
hook per component, just like you can only have a single constructor and destructor.
|
|
]]
|
|
|
|
local jecs = require("@jecs")
|
|
local world = jecs.world()
|
|
|
|
local Transform = world:component()
|
|
|
|
world:set(Transform, jecs.OnAdd, function(entity, id, data)
|
|
-- A transform component id has been added with data to entity
|
|
print(`Transform added to entity {entity}`)
|
|
end)
|
|
|
|
world:set(Transform, jecs.OnRemove, function(entity, id)
|
|
-- A transform component id has been removed from entity
|
|
print(`Transform removed from entity {entity}`)
|
|
end)
|
|
|
|
world:set(Transform, jecs.OnChange, function(entity, id, data)
|
|
-- A transform component id has been changed to data on entity
|
|
print(`Transform changed on entity {entity}`)
|
|
end)
|
|
|
|
--[[
|
|
Children are cleaned up before parents
|
|
When a parent and its children are deleted, OnRemove hooks will be invoked
|
|
for children first, under the condition that there are no cycles in the
|
|
relationship graph of the deleted entities. This order is maintained for any
|
|
relationship that has the (OnDeleteTarget, Delete) trait (see Component Traits
|
|
for more details).
|
|
|
|
When an entity graph contains cycles, order is undefined. This includes cycles
|
|
that can be formed using different relationships.
|
|
]]
|