Monitors and observers need to able to accept pair terms

addons/ob.luau

@@ -69,6 +69,9 @@ local function observers_new<T...>(
 	end
 
 	for _, term in terms do
+		if jecs.IS_PAIR(term) then
+			term = jecs.ECS_PAIR_FIRST(term)
+		end
 		world:added(term, emplaced)
 		world:changed(term, emplaced)
  	end
@@ -151,7 +154,7 @@ local function monitors_new<T...>(
 			i += 1
 			entities[i] = entity
 			if callback ~= nil then
-				callback(entity, id, value)
+				callback(entity, jecs.OnAdd)
 			end
 		end
 	end
@@ -164,6 +167,9 @@ local function monitors_new<T...>(
 	end
 
 	for _, term in terms do
+		if jecs.IS_PAIR(term) then
+			term = jecs.ECS_PAIR_FIRST(term)
+		end
 		world:added(term, emplaced)
 		world:removed(term, removed)
  	end

demo/src/ReplicatedStorage/main.client.luau

@@ -1,12 +1,11 @@
 local ReplicatedStorage = game:GetService("ReplicatedStorage")
 local jecs = require(ReplicatedStorage.ecs)
 local schedule = require(ReplicatedStorage.schedule)
-local observers_add = require(ReplicatedStorage.observers_add)
 
 local SYSTEM = schedule.SYSTEM
 local RUN = schedule.RUN
 require(ReplicatedStorage.components)
-local world = observers_add(jecs.world())
+local world = jecs.world()
 
 local systems = ReplicatedStorage.systems
 SYSTEM(world, systems.receive_replication)

demo/src/ReplicatedStorage/types.luau

@@ -1,7 +1,6 @@
 local jecs = require(game:GetService("ReplicatedStorage").ecs)
-local observers_add = require("../ReplicatedStorage/observers_add")
 
-export type World = typeof(observers_add(jecs.world()))
+export type World = typeof(jecs.world())
 export type Entity = jecs.Entity
 export type Id<T> = jecs.Id<T>
 export type Snapshot = {

package.json

@@ -1,6 +1,6 @@
 {
 	"name": "@rbxts/jecs",
-	"version": "0.9.0-rc.6",
+	"version": "0.9.0-rc.7",
 	"description": "Stupidly fast Entity Component System",
 	"main": "jecs.luau",
 	"repository": {

test/addons/observers.luau

@@ -2,11 +2,28 @@ local jecs = require("@jecs")
 local testkit = require("@testkit")
 local test = testkit.test()
 local CASE, TEST, FINISH, CHECK = test.CASE, test.TEST, test.FINISH, test.CHECK
+local FOCUS = test.FOCUS
 local ob = require("@addons/ob")
 
 TEST("addons/observers", function()
-	local world = jecs.world()
 
+	local world = jecs.world()
+	do CASE "monitors should accept pairs"
+		local A = world:component()
+		local B = world:component()
+
+		local c = 1
+		ob.monitor(world:query(jecs.pair(A, B)), function (_, event)
+			c += 1
+		end)
+
+		local child = world:entity()
+		world:add(child, jecs.pair(A, B))
+		CHECK(c == 2)
+
+		world:remove(child, jecs.pair(A, B))
+		CHECK(c == 3)
+	end
 	do CASE "Ensure ordering between signals and observers"
 		local A = world:component()
 		local B = world:component()

wally.toml

@@ -1,6 +1,6 @@
 [package]
 name = "ukendio/jecs"
-version = "0.9.0-rc.6"
+version = "0.9.0-rc.7"
 registry = "https://github.com/UpliftGames/wally-index"
 realm = "shared"
 license = "MIT"

werewitch.luau

@@ -0,0 +1,66 @@
+local jecs = require("@jecs")
+
+local world = jecs.world()
+local pair = jecs.pair
+
+local IsA = world:entity()
+
+local traits = {
+	IsA = IsA
+}
+
+world:set(IsA, jecs.OnAdd, function(component, id)
+	local second = jecs.pair_second(world, id)
+	assert(second ~= component, "circular")
+
+	local is_tag = jecs.is_tag(world, second)
+	world:added(component, function(entity, _, value)
+		if is_tag then
+			world:add(entity, second)
+		else
+			world:set(entity, second, value)
+		end
+	end)
+
+	world:removed(component, function(entity)
+		world:remove(entity, second)
+	end)
+
+	if not is_tag then
+		world:changed(component, function(entity, _, value)
+			world:set(entity, second, value)
+		end)
+	end
+
+	local r = jecs.record(world, second) :: jecs.Record
+	local archetype = r.archetype
+	if not archetype then
+		return
+	end
+	local types = archetype.types
+
+	for _, id in types do
+		if jecs.is_tag(world, id) then
+			world:add(component, id)
+		else
+			local metadata = world:get(second, id)
+			if not world:has(component, id) then
+				world:set(component, id, metadata)
+			end
+		end
+	end
+
+	-- jecs.bulk_insert(world, component, ids, values)
+end)
+
+local Witch = world:entity()
+local Werewolf = world:entity()
+
+local WereWitch = world:entity()
+world:add(WereWitch, pair(IsA, Witch))
+world:add(WereWitch, pair(IsA, Werewolf))
+
+local e = world:entity()
+world:add(e, WereWitch)
+print(world:has(e, pair(IsA, Witch))) -- false
+print(world:has(e, Witch)) -- true