From c2b408842ea036395cec5bd32bd435c6202e743c Mon Sep 17 00:00:00 2001
From: GsLogimaker <gslogimaker@gmail.com>
Date: Wed, 27 Nov 2024 21:47:53 -0600
Subject: [PATCH 1/7] Rework adding and setting components Setting components
 will now add them. Setting a component member with a wrong value will raise
 an error instead of crashing now. Removed `add_entity`, it was redundent and
 maybe confusing. Updated tests.

---
 .vscode/launch.json                   |   6 +-
 cpp/src/component.cpp                 |  33 +++++
 cpp/src/component.h                   |   1 +
 cpp/src/entity.cpp                    | 182 +++++++++++++++++---------
 cpp/src/entity.h                      |  12 +-
 cpp/src/utils.cpp                     |  72 ++++++++++
 cpp/src/utils.h                       |   1 +
 cpp/src/world.cpp                     |   6 +
 examples/asteroids/asteroids.gd       |  16 +--
 gd/modules.gd                         |   5 +-
 unittests/test_components.gd          |   4 +-
 unittests/test_events.gd              |  12 +-
 unittests/test_module_rendering_2d.gd |   2 +-
 unittests/test_prefab.gd              |   8 +-
 unittests/test_simple_systems.gd      |   2 +-
 15 files changed, 267 insertions(+), 95 deletions(-)

diff --git a/.vscode/launch.json b/.vscode/launch.json
index 3746b7f..dd969b9 100644
--- a/.vscode/launch.json
+++ b/.vscode/launch.json
@@ -9,10 +9,10 @@
             "program": "${config:godotTools.editorPath.godot4}",
       "args": [
         "--path",
-        "../../${workspaceFolder}",
-        "--headless"
+        "./",
+        "--unittest=all"
       ],
-            "cwd": "../../${workspaceFolder}"
+            "cwd": "${workspaceFolder}/../../"
     }
     ]
 }
diff --git a/cpp/src/component.cpp b/cpp/src/component.cpp
index 12baf44..14d8d86 100644
--- a/cpp/src/component.cpp
+++ b/cpp/src/component.cpp
@@ -306,6 +306,39 @@ void GFComponent::build_data_from_variant(
 	}
 }
 
+void GFComponent::build_data_from_members(
+	Array members,
+	void* output,
+	ecs_entity_t component_id,
+	GFWorld* world
+) {
+	ecs_world_t* w_raw = world->raw();
+
+	const EcsStruct* struct_data = ecs_get(w_raw, component_id, EcsStruct);
+	if (struct_data == nullptr) {
+		ERR(/**/,
+			"Could not build data from Variant\n",
+			"Component is not a struct."
+		);
+	}
+
+	for (int i=0; i != members.size() && i != ecs_vec_size(&struct_data->members); i++) {
+		// Iterate the combined sizes of the passed array and the members vector
+		Variant value = members[i];
+
+		ecs_member_t* member_data = /* Get member metadata */ ecs_vec_get_t(
+			&struct_data->members,
+			ecs_member_t,
+			i
+		);
+		void* member_ptr = /* Get member pointer */ static_cast<void*>(
+			static_cast<uint8_t*>(output) + member_data->offset
+		);
+		// Set member value
+		Utils::set_type_from_variant(value, member_data->type, w_raw, member_ptr);
+	}
+}
+
 void GFComponent::set_source_id(ecs_entity_t id) {
 	source_entity_id = id;
 }
diff --git a/cpp/src/component.h b/cpp/src/component.h
index 893f60a..909d2c4 100644
--- a/cpp/src/component.h
+++ b/cpp/src/component.h
@@ -50,6 +50,7 @@ namespace godot {
 		void _register_internal();
 
 		void build_data_from_variant(Variant, void* output);
+		static void build_data_from_members(Array, void*, ecs_entity_t, GFWorld*);
 		void set_source_id(ecs_entity_t id);
 
 		static Ref<GFRegisterableEntity> new_internal();
diff --git a/cpp/src/entity.cpp b/cpp/src/entity.cpp
index e38007e..7f1f936 100644
--- a/cpp/src/entity.cpp
+++ b/cpp/src/entity.cpp
@@ -1,6 +1,7 @@
 
 #include "entity.h"
 #include "godot_cpp/classes/script.hpp"
+#include "godot_cpp/variant/array.hpp"
 #include "utils.h"
 // needed here because entity.h does not include
 // component.h, but uses forward declaration instead
@@ -31,54 +32,63 @@ Ref<GFEntity> GFEntity::from_id(ecs_entity_t id, GFWorld* world) {
 	return from_id_template<GFEntity>(id, world);
 }
 
-Ref<GFEntity> GFEntity::add_component(Variant component, Variant data) {
-	GFWorld* w = get_world();
-
-	ecs_entity_t c_id = w->coerce_id(component);
-
-	if (ECS_IS_PAIR(c_id)) {
-		add_pair(
-			ECS_PAIR_FIRST(c_id),
-			ECS_PAIR_SECOND(c_id),
-			data
-		);
-		return Ref(this);
+Ref<GFEntity> GFEntity::add_component(
+	const Variant** args, GDExtensionInt arg_count, GDExtensionCallError &error
+) {
+	if (arg_count < 1) {
+		// Too few arguments, return with error.
+		error.error = GDExtensionCallErrorType::GDEXTENSION_CALL_ERROR_TOO_FEW_ARGUMENTS;
+		error.argument = arg_count;
+		error.expected = 1;
+		return this;
 	}
 
-	if (!ecs_has_id(w->raw(), c_id, ecs_id(EcsComponent))) {
-		ERR(Ref(this),
-			"Failed to add component to entity\n",
-			"ID coerced from ", component, " is not a component"
-		);
+	// Parse arguments
+	Array members = Array();
+	members.resize(arg_count);
+	for (int i=0; i != arg_count; i++) {
+		members[i] = *args[i];
 	}
+	Variant comopnent = members.pop_front();
 
-	ecs_add_id(w->raw(), get_id(), c_id);
-
-	if (data != Variant()) {
-		set_component(c_id, data);
-	}
+	_add_component(comopnent, members);
 
-	return Ref(this);
+	return this;
 }
 
-Ref<GFEntity> GFEntity::add_entity(Variant entity, Variant data) {
+Ref<GFEntity> GFEntity::_add_component(Variant component, Array members) {
 	GFWorld* w = get_world();
 
-	ecs_add_id(w->raw(), get_id(), w->coerce_id(entity));
-	if (data != Variant()) {
-		set_component(entity, data);
+	ecs_entity_t c_id = w->coerce_id(component);
+
+	if (ecs_has_id(w->raw(), get_id(), c_id)) {
+		ERR(this,
+			"Can't add component to entity\n",
+			"ID coerced from ", component, " is already added to ", get_id()
+		)
 	}
 
-	return Ref(this);
+	_set_component(c_id, members);
+
+	return this;
 }
 
-Ref<GFEntity> GFEntity::add_pair(Variant first, Variant second, Variant data) {
+Ref<GFEntity> GFEntity::add_pair(Variant first, Variant second, Array members) {
 	GFWorld* w = get_world();
 
 	ecs_entity_t first_id = w->coerce_id(first);
 	ecs_entity_t second_id = w->coerce_id(second);
 	ecs_entity_t pair_id = w->pair_ids(first_id, second_id);
-	add_entity(pair_id, data);
+	if (
+		members.size() != 0
+		|| ecs_has_id(w->raw(), pair_id, FLECS_IDEcsComponentID_)
+	) {
+		// Add pair as a component
+		_add_component(pair_id, members);
+	} else {
+		// Add pair as a dataless tag
+		add_tag(pair_id);
+	}
 
 	return Ref(this);
 }
@@ -87,11 +97,12 @@ Ref<GFEntity> GFEntity::add_tag(Variant tag) {
 	GFWorld* w = get_world();
 
 	ecs_entity_t tag_id = w->coerce_id(tag);
+
 	if (ecs_has(w->raw(), tag_id, EcsComponent)) {
 		ERR(Ref(this),
 			"Failed to add tag to entity\n",
-			"ID, ", tag_id, "is a component, not a tag\n"
-			"(Tags are any non-component entity)"
+			"	ID, ", tag_id, " is a component, not a tag\n"
+			"	(Tags are any entity with no data)"
 		);
 	}
 
@@ -121,41 +132,74 @@ Ref<GFComponent> GFEntity::get_component(Variant component) {
 	return c;
 }
 
-Ref<GFEntity> GFEntity::set_component(Variant component, Variant data) {
-	GFWorld* world = get_world();
+Ref<GFEntity> GFEntity::set_component(
+	const Variant** args, GDExtensionInt arg_count, GDExtensionCallError &error
+) {
+	if (arg_count < 1) {
+		// Too few arguments, return with error.
+		error.error = GDExtensionCallErrorType::GDEXTENSION_CALL_ERROR_TOO_FEW_ARGUMENTS;
+		error.argument = arg_count;
+		error.expected = 1;
+		return this;
+	}
+
+	// Parse arguments
+	Array members = Array();
+	members.resize(arg_count);
+	for (int i=0; i != arg_count; i++) {
+		members[i] = *args[i];
+	}
+	Variant comopnent = members.pop_front();
+
+	return _set_component(comopnent, members);
+}
+
+Ref<GFEntity> GFEntity::_set_component(
+	Variant component,
+	Array members
+) {
+	GFWorld* w = get_world();
 
-	ecs_entity_t id = world->coerce_id(component);
+	ecs_entity_t c_id = w->coerce_id(component);
 
-	if (!ECS_IS_PAIR(id)) {
-		if (!ecs_has(world->raw(), id, EcsComponent)) {
+	if (!ecs_has_id(w->raw(), get_id(), c_id)) {
+		// Component is not present in entity, add it
+
+		if (ECS_IS_PAIR(c_id)) {
+			// ID is a pair, perform pair specific checks
+			ecs_entity_t first_id = ECS_PAIR_FIRST(c_id);
+			ecs_entity_t second_id = ECS_PAIR_SECOND(c_id);
+			if (
+				!ecs_has_id(w->raw(), first_id, ecs_id(EcsComponent))
+				&& !ecs_has_id(w->raw(), second_id, ecs_id(EcsComponent))
+			) {
+				// ID is not a component, error
+				ERR(Ref(this),
+					"Failed to set data in pair\n",
+					"Neither ID ", first_id,
+					" nor ", second_id, "are components"
+				);
+			}
+
+		} else if (!ecs_has_id(w->raw(), c_id, ecs_id(EcsComponent))) {
+			// Error, passed variant is not a real component
 			ERR(Ref(this),
-				"Failed to set data in component\n",
-				"ID, ", id, "is not a component"
-			);
-		}
-	} else {
-		ecs_entity_t first_id = ECS_PAIR_FIRST(id);
-		ecs_entity_t second_id = ECS_PAIR_SECOND(id);
-		if (
-			!ecs_has_id(world->raw(), first_id, ecs_id(EcsComponent))
-			&& !ecs_has_id(world->raw(), second_id, ecs_id(EcsComponent))
-		) {
-			// ID is not a component, err
-			ERR(Ref(this),
-				"Failed to set data in pair\n",
-				"Neither ID ", first_id,
-				" nor ", second_id, "are components"
+				"Failed to add component to entity\n",
+				"ID coerced from ", component, " is not a component"
 			);
+
 		}
+
+		ecs_add_id(w->raw(), get_id(), c_id);
 	}
 
-	// TODO: change build_data_from_variant to a static method
-	Ref(memnew(GFComponent(get_id(), id, world)))
-		->build_data_from_variant(
-			data,
-			ecs_get_mut_id(world->raw(), get_id(), id)
-		);
-	ecs_modified_id(world->raw(), get_id(), id);
+	GFComponent::build_data_from_members(
+		members,
+		ecs_get_mut_id(w->raw(), get_id(), c_id),
+		c_id,
+		get_world()
+	);
+	ecs_modified_id(w->raw(), get_id(), c_id);
 
 	return Ref(this);
 }
@@ -270,12 +314,22 @@ void GFEntity::_bind_methods() {
 	godot::ClassDB::bind_static_method(GFEntity::get_class_static(), D_METHOD("from", "entity", "world"), &GFEntity::from, nullptr);
 	godot::ClassDB::bind_static_method(GFEntity::get_class_static(), D_METHOD("from_id", "id", "world"), &GFEntity::from_id, nullptr);
 
-	godot::ClassDB::bind_method(D_METHOD("add_component", "component", "data"), &GFEntity::add_component, nullptr);
-	godot::ClassDB::bind_method(D_METHOD("add_entity", "entity", "data"), &GFEntity::add_entity, nullptr);
-	godot::ClassDB::bind_method(D_METHOD("add_pair", "first", "second", "data"), &GFEntity::add_pair, nullptr);
+	{
+		MethodInfo mi;
+		mi.arguments.push_back(PropertyInfo(Variant::NIL, "component"));
+		mi.name = "add_component";
+		godot::ClassDB::bind_vararg_method(METHOD_FLAGS_DEFAULT, StringName("add_component"), &GFEntity::add_component, mi);
+	}
+	{
+		MethodInfo mi;
+		mi.arguments.push_back(PropertyInfo(Variant::NIL, "component"));
+		mi.name = "set_component";
+		godot::ClassDB::bind_vararg_method(METHOD_FLAGS_DEFAULT, StringName("set_component"), &GFEntity::set_component, mi);
+	}
+
+	godot::ClassDB::bind_method(D_METHOD("add_pair", "first", "second", "data"), &GFEntity::add_pair, Array());
 	godot::ClassDB::bind_method(D_METHOD("add_tag", "tag"), &GFEntity::add_tag);
 	godot::ClassDB::bind_method(D_METHOD("get_component", "component"), &GFEntity::get_component);
-	godot::ClassDB::bind_method(D_METHOD("set_component", "component", "value"), &GFEntity::set_component);
 
 	godot::ClassDB::bind_method(D_METHOD("delete"), &GFEntity::delete_);
 
diff --git a/cpp/src/entity.h b/cpp/src/entity.h
index f80b35b..2cc02ae 100644
--- a/cpp/src/entity.h
+++ b/cpp/src/entity.h
@@ -35,13 +35,17 @@ namespace godot {
 		static Ref<GFEntity> from(Variant, GFWorld*);
 		static Ref<GFEntity> from_id(ecs_entity_t, GFWorld*);
 
-		Ref<GFEntity> add_component(Variant, Variant data);
-		Ref<GFEntity> add_entity(Variant, Variant data);
-		Ref<GFEntity> add_pair(Variant, Variant, Variant data);
+		Ref<GFEntity> add_component(const Variant**, GDExtensionInt, GDExtensionCallError&);
+		Ref<GFEntity> _add_component(Variant, Array);
+
+		Ref<GFEntity> add_pair(Variant, Variant, Array data);
 		Ref<GFEntity> add_tag(Variant);
 
 		Ref<GFComponent> get_component(Variant);
-		Ref<GFEntity> set_component(Variant, Variant data);
+
+		Ref<GFEntity> set_component(const Variant**, GDExtensionInt, GDExtensionCallError&);
+		Ref<GFEntity> _set_component(Variant, Array);
+
 
 		void delete_();
 
diff --git a/cpp/src/utils.cpp b/cpp/src/utils.cpp
index 183b97c..2c6dcfe 100644
--- a/cpp/src/utils.cpp
+++ b/cpp/src/utils.cpp
@@ -1,6 +1,7 @@
 
 #include "utils.h"
 #include "godot_cpp/core/defs.hpp"
+#include "godot_cpp/variant/utility_functions.hpp"
 #include "godot_cpp/variant/variant.hpp"
 #include "world.h"
 
@@ -159,6 +160,70 @@ void Utils::set_gd_struct_from_variant(
 	}
 }
 
+bool Utils::can_convert_type_to_primitive(Variant::Type type, ecs_primitive_kind_t primi) {
+	switch (type) {
+        case Variant::NIL:
+			return false;
+        case Variant::BOOL:
+			return primi == ecs_primitive_kind_t::EcsBool;
+        case Variant::INT: {
+			switch (primi) {
+				case EcsU8: case EcsU16: case EcsU32: case EcsU64:
+				case EcsI8: case EcsI16: case EcsI32: case EcsI64:
+					return true;
+				default:
+					return false;
+			}
+		}
+        case Variant::FLOAT: {
+			switch (primi) {
+				case EcsF32: case EcsF64:
+					return true;
+				default:
+					return false;
+        	}
+		}
+        case Variant::STRING:
+        case Variant::VECTOR2:
+        case Variant::VECTOR2I:
+        case Variant::RECT2:
+        case Variant::RECT2I:
+        case Variant::VECTOR3:
+        case Variant::VECTOR3I:
+        case Variant::TRANSFORM2D:
+        case Variant::VECTOR4:
+        case Variant::VECTOR4I:
+        case Variant::PLANE:
+        case Variant::QUATERNION:
+        case Variant::AABB:
+        case Variant::BASIS:
+        case Variant::TRANSFORM3D:
+        case Variant::PROJECTION:
+        case Variant::COLOR:
+        case Variant::STRING_NAME:
+        case Variant::NODE_PATH:
+        case Variant::RID:
+        case Variant::OBJECT:
+        case Variant::CALLABLE:
+        case Variant::SIGNAL:
+        case Variant::DICTIONARY:
+        case Variant::ARRAY:
+        case Variant::PACKED_BYTE_ARRAY:
+        case Variant::PACKED_INT32_ARRAY:
+        case Variant::PACKED_INT64_ARRAY:
+        case Variant::PACKED_FLOAT32_ARRAY:
+        case Variant::PACKED_FLOAT64_ARRAY:
+        case Variant::PACKED_STRING_ARRAY:
+        case Variant::PACKED_VECTOR2_ARRAY:
+        case Variant::PACKED_VECTOR3_ARRAY:
+        case Variant::PACKED_COLOR_ARRAY:
+        case Variant::PACKED_VECTOR4_ARRAY:
+        case Variant::VARIANT_MAX:
+			return false;
+	}
+	return false;
+}
+
 void Utils::set_primitive_from_variant(
 	const Variant value,
 	const ecs_primitive_kind_t primi_kind,
@@ -194,6 +259,13 @@ void Utils::set_type_from_variant(
 ) {
 	const EcsPrimitive* primi = ecs_get(world, type, EcsPrimitive);
 	if (primi != nullptr) {
+		if (!Utils::can_convert_type_to_primitive(value.get_type(), primi->kind)) {
+			// TODO: Display names of primitive and variant type, instead of numbers
+			ERR(/**/, "Set value failed.\n",
+				"Setting Flecs primitive type, ", primi->kind, ", to value of Godot type, ",
+				value.get_type(), ", is invalid."
+			);
+		}
 		set_primitive_from_variant(value, primi->kind, out);
 		return;
 	}
diff --git a/cpp/src/utils.h b/cpp/src/utils.h
index fa060a1..73623d9 100644
--- a/cpp/src/utils.h
+++ b/cpp/src/utils.h
@@ -94,6 +94,7 @@ namespace godot {
 		static Variant primitive_value_to_variant(const void*, ecs_primitive_kind_t);
 		static Variant::Type primitive_type_to_variant(ecs_primitive_kind_t);
 		static EntityResult variant_type_to_id(Variant::Type type);
+		static bool can_convert_type_to_primitive(Variant::Type type, ecs_primitive_kind_t primi);
 
 		static String into_pascal_case(String str);
 
diff --git a/cpp/src/world.cpp b/cpp/src/world.cpp
index daa1ce9..7a9c948 100644
--- a/cpp/src/world.cpp
+++ b/cpp/src/world.cpp
@@ -690,6 +690,12 @@ ecs_entity_t GFWorld::register_script_id(Ref<Script> script) {
 }
 
 Ref<GFRegisterableEntity> GFWorld::register_script_id_no_user_call(Ref<Script> script) {
+	if (*script == nullptr) {
+		ERR(nullptr,
+			"Could not register script\n",
+			"Script is null."
+		);
+	}
 	if (!godot::ClassDB::is_parent_class(
 		script->get_instance_base_type(),
 		GFRegisterableEntity::get_class_static()
diff --git a/examples/asteroids/asteroids.gd b/examples/asteroids/asteroids.gd
index 3266511..73d707a 100644
--- a/examples/asteroids/asteroids.gd
+++ b/examples/asteroids/asteroids.gd
@@ -8,17 +8,17 @@ var texture:= load("res://icon.png")
 
 # Called when the node enters the scene tree for the first time.
 func _ready() -> void:
-	GFEntity.spawn(world) \
-		.set_name("Test") \
-		.add_component(GFTexture2D, [texture]) \
-		.add_component(GFCanvasItem) \
-		.add_component(GFPosition2D)
+	#GFEntity.spawn(world) \
+		#.set_name("Test") \
+		#.add_component(GFTexture2D, [texture]) \
+		#.add_component(GFCanvasItem) \
+		#.add_component(GFPosition2D)
 	
 	world.start_rest_api()
 
 
 func _process(delta: float) -> void:
 	world.progress(delta)
-	world.lookup("Test") \
-		.get_component(GFPosition2D) \
-		.set_vec(get_global_mouse_position())
+	#world.lookup("Test") \
+		#.get_component(GFPosition2D) \
+		#.set_vec(get_global_mouse_position())
diff --git a/gd/modules.gd b/gd/modules.gd
index 690cc33..33662bc 100644
--- a/gd/modules.gd
+++ b/gd/modules.gd
@@ -5,7 +5,7 @@
 class_name _GlecsModules extends Node
 
 const MODULES:= [
-	preload("./rendering/rendering.gd"),
+	"./rendering/rendering.gd",
 ]
 
 static var _register_self_singleton = (func():
@@ -13,5 +13,6 @@ static var _register_self_singleton = (func():
 	).call()
 
 static func register_modules(w:GFWorld) -> void:
+	var path:= (_GlecsModules as Script).resource_path.path_join("../")
 	for module in MODULES:
-		w.register_script(module)
+		w.register_script(load(path.path_join(module)))
diff --git a/unittests/test_components.gd b/unittests/test_components.gd
index 7d318bf..36d2e30 100644
--- a/unittests/test_components.gd
+++ b/unittests/test_components.gd
@@ -3,11 +3,11 @@ extends GutTest
 
 var world:GFWorld = null
 
-func before_all():
+func before_each():
 	world = GFWorld.new()
 
 
-func after_all():
+func after_each():
 	world.free()
 
 
diff --git a/unittests/test_events.gd b/unittests/test_events.gd
index 5114c33..bef6c6b 100644
--- a/unittests/test_events.gd
+++ b/unittests/test_events.gd
@@ -1,12 +1,12 @@
 
 extends GutTest
 
-var world:GFWorld
+var world:GFWorld = null
 
-func before_all():
+func before_each():
 	world = GFWorld.new()
 
-func after_all():
+func after_each():
 	world.free()
 
 #region Tests
@@ -49,7 +49,7 @@ func test_on_set_event():
 			)
 
 	var e:= GFEntity.spawn(world) \
-		.add_component(Ints, [2, 31]) \
+		.add_component(Ints, 2, 31) \
 		.set_name("WithInts")
 	var e2:= GFEntity.spawn(world) \
 		.set_name("WithoutInts")
@@ -58,7 +58,7 @@ func test_on_set_event():
 	var e4:= GFEntity.spawn(world) \
 		.set_name("WithoutInts")
 
-	e3.add_component(Ints, [99, 2])
+	e3.add_component(Ints, 99, 2)
 
 	assert_eq(data.i, 2 + 31 + 99 + 2)
 
@@ -89,7 +89,7 @@ func test_on_add_event_with_objects():
 	data.i = 0
 	var e2:= GFEntity.spawn(world) \
 		.set_name("WithTextures")
-	e2.add_component(Textures, [load("res://icon.png")])
+	e2.add_component(Textures, load("res://icon.png"))
 	assert_eq(data.i, 1)
 	assert_eq(e2.get_component(Textures).a, load("res://icon.png"))
 
diff --git a/unittests/test_module_rendering_2d.gd b/unittests/test_module_rendering_2d.gd
index 6429133..6a01141 100644
--- a/unittests/test_module_rendering_2d.gd
+++ b/unittests/test_module_rendering_2d.gd
@@ -15,7 +15,7 @@ func after_each():
 
 func test_rendering_texture():
 	var e:= GFEntity.spawn(world) \
-		.add_component(GFTexture2D, [TEXTURE]) \
+		.add_component(GFTexture2D, TEXTURE) \
 		.add_component(GFCanvasItem)
 
 	var draw_rect:= RenderingServer.debug_canvas_item_get_rect(
diff --git a/unittests/test_prefab.gd b/unittests/test_prefab.gd
index 1768494..c28f34c 100644
--- a/unittests/test_prefab.gd
+++ b/unittests/test_prefab.gd
@@ -29,7 +29,7 @@ func test_prefab():
 	var isa:= world.coerce_id("flecs/core/IsA")
 	var myprefab:= world.coerce_id(MyPrefab)
 	var pair:= world.pair(isa, myprefab)
-	entity.add_entity(pair)
+	entity.add_tag(pair)
 
 	# Test inhereted components exist entity
 	var foo:Foo = entity.get_component(Foo)
@@ -83,8 +83,8 @@ class Bar extends GFComponent:
 
 class MyPrefab extends GFRegisterableEntity:
 	func _register(_world:GFWorld) -> void:
-		add_entity("flecs/core/Prefab")
-		add_component(Foo, [true, 23, 2.33])
-		add_component(Bar, [Vector2(2, 1.1), 5.6])
+		add_tag("flecs/core/Prefab")
+		add_component(Foo, true, 23, 2.33)
+		add_component(Bar, Vector2(2, 1.1), 5.6)
 
 #endregion
diff --git a/unittests/test_simple_systems.gd b/unittests/test_simple_systems.gd
index 463dc43..dae5323 100644
--- a/unittests/test_simple_systems.gd
+++ b/unittests/test_simple_systems.gd
@@ -123,7 +123,7 @@ func test_strings():
 
 	var entity:= GFEntity.spawn(world) \
 		.set_name("Test") \
-		.add_component(Strings, ["", "po"])
+		.add_component(Strings, "", "po")
 	var strings:Strings = entity.get_component(Strings)
 	assert_eq(strings.a, "")
 	assert_eq(strings.b, "po")

From d66825957f641c0a6eea0dbbc3420d8792a677b6 Mon Sep 17 00:00:00 2001
From: GsLogiMaker <gslogimaker@gmail.com>
Date: Fri, 29 Nov 2024 16:32:14 -0600
Subject: [PATCH 2/7] Fix crash when re-compiling Glecs lib

---
 cpp/src/component_builder.cpp | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/cpp/src/component_builder.cpp b/cpp/src/component_builder.cpp
index 6b873a5..bbecdc0 100644
--- a/cpp/src/component_builder.cpp
+++ b/cpp/src/component_builder.cpp
@@ -74,11 +74,22 @@ Ref<GFComponentBuilder> GFComponentBuilder::set_name(
 }
 
 void GFComponentBuilder::build() {
-	const char* FAILED_TO_BUILD = "Failed to build component\n";
+	if (name.length() == 0) {
+		ERR(/**/,
+			"Failed to build component.\n",
+			"	No name provided. Specify the name of the component."
+		);
+	}
 	if (built) {
 		ERR(/**/,
-			FAILED_TO_BUILD,
-			"Component builder was already built"
+			"Failed to build component \"" + name + "\".\n",
+			"	Component is already built."
+		);
+	}
+	if (get_member_count() == 0) {
+		ERR(/**/,
+			"Failed to build component \"" + name + "\".\n",
+			"	No members were defined. Specify at least one member."
 		);
 	}
 	built = true;

From d72a3e6866ce1b8c19664c70f16628eae7ccb2b6 Mon Sep 17 00:00:00 2001
From: GsLogiMaker <gslogimaker@gmail.com>
Date: Fri, 29 Nov 2024 16:33:23 -0600
Subject: [PATCH 3/7] Fix way GFCanvasItem adds itself to canvas

---
 gd/rendering/2d/canvas_item.gd | 16 ++++++++++++++++
 gd/rendering/2d/systems.gd     |  8 ++++----
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/gd/rendering/2d/canvas_item.gd b/gd/rendering/2d/canvas_item.gd
index c03f24c..f407e28 100644
--- a/gd/rendering/2d/canvas_item.gd
+++ b/gd/rendering/2d/canvas_item.gd
@@ -9,6 +9,22 @@ func _build(b: GFComponentBuilder) -> void:
 	b.add_member("rid", TYPE_RID)
 	
 
+static func get_main_viewport_rid() -> RID:
+	return Engine.get_main_loop() \
+		.current_scene \
+		.get_viewport() \
+		.get_viewport_rid()
+
+
+static func get_main_canvas() -> RID:
+	return Engine.get_main_loop() \
+		.current_scene \
+		.get_viewport() \
+		.get_world_2d() \
+		.get_canvas()
+		
+
+
 ## Sets the parent canvas item of this canvas item by its [RID].
 func set_parent_canvas_item(rid:RID) -> void:
 	RenderingServer.canvas_item_set_parent(
diff --git a/gd/rendering/2d/systems.gd b/gd/rendering/2d/systems.gd
index 667568d..de13ffe 100644
--- a/gd/rendering/2d/systems.gd
+++ b/gd/rendering/2d/systems.gd
@@ -11,9 +11,9 @@ func _register(w:GFWorld):
 		.for_each(func(item:GFCanvasItem):
 			item.set_rid(RenderingServer.canvas_item_create())
 			# Set parent to root
-			var root_canvas_item:CanvasItem =  Engine.get_main_loop() \
-				.current_scene
-			item.set_parent_canvas_item(root_canvas_item.get_canvas_item())
+			item.set_parent_canvas_item(
+				GFCanvasItem.get_main_canvas()
+				)
 			)
 
 	# On set GFCanvasItem
@@ -21,7 +21,7 @@ func _register(w:GFWorld):
 		.with(GFCanvasItem) \
 		.for_each(func(item:GFCanvasItem):
 			item.set_parent_canvas_item(
-				Engine.get_main_loop().current_scene.get_canvas_item()
+				GFCanvasItem.get_main_canvas()
 				)
 			)
 

From 60757c2848d078adb4c5bc1411b8a765451d206a Mon Sep 17 00:00:00 2001
From: GsLogiMaker <gslogimaker@gmail.com>
Date: Fri, 29 Nov 2024 20:52:19 -0600
Subject: [PATCH 4/7] Remove name check from component builder

---
 cpp/src/component_builder.cpp   |  6 ------
 examples/asteroids/asteroids.gd | 19 +++++++++----------
 2 files changed, 9 insertions(+), 16 deletions(-)

diff --git a/cpp/src/component_builder.cpp b/cpp/src/component_builder.cpp
index bbecdc0..57a80db 100644
--- a/cpp/src/component_builder.cpp
+++ b/cpp/src/component_builder.cpp
@@ -74,12 +74,6 @@ Ref<GFComponentBuilder> GFComponentBuilder::set_name(
 }
 
 void GFComponentBuilder::build() {
-	if (name.length() == 0) {
-		ERR(/**/,
-			"Failed to build component.\n",
-			"	No name provided. Specify the name of the component."
-		);
-	}
 	if (built) {
 		ERR(/**/,
 			"Failed to build component \"" + name + "\".\n",
diff --git a/examples/asteroids/asteroids.gd b/examples/asteroids/asteroids.gd
index 73d707a..266f716 100644
--- a/examples/asteroids/asteroids.gd
+++ b/examples/asteroids/asteroids.gd
@@ -1,24 +1,23 @@
 
 extends Node2D
 
-
 var world:= GFWorld.new()
 
 var texture:= load("res://icon.png")
 
 # Called when the node enters the scene tree for the first time.
 func _ready() -> void:
-	#GFEntity.spawn(world) \
-		#.set_name("Test") \
-		#.add_component(GFTexture2D, [texture]) \
-		#.add_component(GFCanvasItem) \
-		#.add_component(GFPosition2D)
-	
+	GFEntity.spawn(world) \
+		.set_name("Test") \
+		.add_component(GFTexture2D, texture) \
+		.add_component(GFCanvasItem) \
+		.add_component(GFPosition2D)
+
 	world.start_rest_api()
 
 
 func _process(delta: float) -> void:
 	world.progress(delta)
-	#world.lookup("Test") \
-		#.get_component(GFPosition2D) \
-		#.set_vec(get_global_mouse_position())
+	world.lookup("Test") \
+		.get_component(GFPosition2D) \
+		.set_vec(get_global_mouse_position())

From 77d371c51277fdfa3f0a0dab03bcd6b9c1f27d4c Mon Sep 17 00:00:00 2001
From: GsLogiMaker <gslogimaker@gmail.com>
Date: Fri, 29 Nov 2024 22:10:06 -0600
Subject: [PATCH 5/7] Update docs related to changes

---
 cpp/src/doc_classes/GFComponent.xml |  7 +++---
 cpp/src/doc_classes/GFEntity.xml    | 35 ++++++++++++++++++++++++-----
 2 files changed, 34 insertions(+), 8 deletions(-)

diff --git a/cpp/src/doc_classes/GFComponent.xml b/cpp/src/doc_classes/GFComponent.xml
index 40a62a6..dd45159 100644
--- a/cpp/src/doc_classes/GFComponent.xml
+++ b/cpp/src/doc_classes/GFComponent.xml
@@ -1,5 +1,6 @@
 <?xml version="1.0" encoding="UTF-8" ?>
-<class name="GFComponent" inherits="GFRegisterableEntity" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="https://raw.githubusercontent.com/godotengine/godot/master/doc/class.xsd">
+<class name="GFComponent" inherits="GFRegisterableEntity"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="https://raw.githubusercontent.com/godotengine/godot/master/doc/class.xsd">
 	<brief_description>
 		A reference to a Glecs component from a [GFWorld] that is attatached to an entity.
 	</brief_description>
@@ -55,7 +56,7 @@
 			<return type="Variant" />
 			<param index="0" name="member" type="String" />
 			<description>
-				Returns the value of a component's member
+				Returns the value of a component's member.
 				[codeblock]
 				var entity = GFEntity.spawn()
 				entity.add_component("glecs/meta/Vector2")
@@ -70,7 +71,7 @@
 			<param index="0" name="member" type="String" />
 			<param index="1" name="value" type="Variant" />
 			<description>
-				Sets the value of a component's member
+				Sets the value of a component's member.
 				[codeblock]
 				var entity = GFEntity.spawn()
 				entity.add_component("glecs/meta/Vector2")
diff --git a/cpp/src/doc_classes/GFEntity.xml b/cpp/src/doc_classes/GFEntity.xml
index 0942b6f..8ad4119 100644
--- a/cpp/src/doc_classes/GFEntity.xml
+++ b/cpp/src/doc_classes/GFEntity.xml
@@ -1,5 +1,6 @@
 <?xml version="1.0" encoding="UTF-8" ?>
-<class name="GFEntity" inherits="RefCounted" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="https://raw.githubusercontent.com/godotengine/godot/master/doc/class.xsd">
+<class name="GFEntity" inherits="RefCounted"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="https://raw.githubusercontent.com/godotengine/godot/master/doc/class.xsd">
 	<brief_description>
 		A reference to an entity from a [GFWorld].
 	</brief_description>
@@ -9,7 +10,7 @@
 		<link title="More on Flecs Entities">https://www.flecs.dev/flecs/md_docs_2EntitiesComponents.html</link>
 	</tutorials>
 	<methods>
-		<method name="add_component">
+		<method name="add_component" qualifiers="const vararg">
 			<return type="GFEntity" />
 			<param index="0" name="component" type="Variant" />
 			<description>
@@ -17,9 +18,10 @@
 				The component's type ID is coerced from a [Variant]. To learn more about [Variant] coercion see [method GFWorld.coerce_id].
 				[codeblock]
 				var entity:= GFEntity.spawn()
-				entity.add_component("glecs/meta/Array")
-				entity.get_component("glecs/meta/Array") != null # true
+				entity.add_component(GFPosition2D, Vector2(10, 10))
+				entity.get_component(GFPosition2D).get_vec() == Vector2(10, 10) # true
 				[/codeblock]
+				This method returns [code]self[/code] for chaining.
 			</description>
 		</method>
 		<method name="from" qualifiers="static">
@@ -135,8 +137,30 @@
 				[codeblock]
 				var Eats:= GFEntity.spawn()
 				var Grass:= GFEntity.spawn()
-				var EatsGrass_id:int = Eats.pair(Grass.get_id())
+				var EatsGrass_id:int = Eats.pair_id(Grass.get_id())
+				[/codeblock]
+			</description>
+		</method>
+		<method name="set_component" qualifiers="const vararg">
+			<return type="GFEntity" />
+			<param index="0" name="component" type="Variant" />
+			<description>
+				Sets component data of type [param component] in this entity.
+				The component's type ID is coerced from a [Variant]. To learn more about [Variant] coercion see [method GFWorld.coerce_id].
+				[codeblock]
+				var entity:= GFEntity.spawn()
+				entity.add_component(GFPosition2D)
+				entity.set_component(GFPosition2D, Vector2(10, 10))
+				entity.get_component(GFPosition2D).get_vec() == Vector2(10, 10) # true
+				[/codeblock]
+				If the component is not added yet, then this method will add
+				it automaticly.
+				[codeblock]
+				var entity:= GFEntity.spawn()
+				entity.set_component(GFPosition2D, Vector2(10, 10))
+				entity.get_component(GFPosition2D).get_vec() == Vector2(10, 10) # true
 				[/codeblock]
+				This method returns [code]self[/code] for chaining.
 			</description>
 		</method>
 		<method name="set_name">
@@ -149,6 +173,7 @@
 				entity.set_name("Entity")
 				entity.get_name() == "Entity" # true
 				[/codeblock]
+				This method returns [code]self[/code] for chaining.
 			</description>
 		</method>
 		<method name="spawn" qualifiers="static">

From df2fb925c28fda18a2489abe39bbf5fdc6d54a82 Mon Sep 17 00:00:00 2001
From: GsLogiMaker <gslogimaker@gmail.com>
Date: Fri, 29 Nov 2024 22:11:08 -0600
Subject: [PATCH 6/7] Fix doc dump vscode task

---
 .vscode/tasks.json | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.vscode/tasks.json b/.vscode/tasks.json
index c56f5bb..53b48fc 100644
--- a/.vscode/tasks.json
+++ b/.vscode/tasks.json
@@ -27,7 +27,7 @@
 			"label": "godot-extension: Doctool Dump Documentation Files",
 			"detail": "Dumps GDExtension documentation xml files",
 			"type": "shell",
-			"command": "${config:godotTools.editorPath.godot4} --doctool ./cpp/src/ --gdextension-docs --editor --headless --quit",
+			"command": "cd ../../ && ${config:godotTools.editorPath.godot4} --doctool ./addons/glecs/cpp/src --gdextension-docs --editor --headless --quit",
 			"problemMatcher": []
 		}
 	]

From 8d8f027ca91c4e703b49f55b9c36f4353c7ea9f7 Mon Sep 17 00:00:00 2001
From: GsLogiMaker <gslogimaker@gmail.com>
Date: Sun, 1 Dec 2024 14:16:50 -0600
Subject: [PATCH 7/7] Support varargs in pair functions

---
 cpp/src/component.cpp            | 27 +++++++---
 cpp/src/component.h              |  3 ++
 cpp/src/doc_classes/GFEntity.xml | 49 +++++++++++++++++
 cpp/src/entity.cpp               | 84 ++++++++++++++++++++++++++++-
 cpp/src/entity.h                 | 13 +++--
 cpp/src/register_types.cpp       | 69 ++++++++++++++----------
 cpp/src/world.cpp                | 67 +++++++++++++++++++----
 cpp/src/world.h                  |  3 ++
 gd/modules.gd                    |  4 +-
 plugin.gd                        |  1 +
 unittests/test_relations.gd      | 91 +++++++++++++++++++++++---------
 11 files changed, 330 insertions(+), 81 deletions(-)

diff --git a/cpp/src/component.cpp b/cpp/src/component.cpp
index 14d8d86..c8a1e8f 100644
--- a/cpp/src/component.cpp
+++ b/cpp/src/component.cpp
@@ -35,10 +35,11 @@ Ref<GFComponent> GFComponent::from(Variant comp, Variant entity, GFWorld* world)
 	return from_id(world->coerce_id(comp), world->coerce_id(entity), world);
 }
 Ref<GFComponent> GFComponent::from_id(ecs_entity_t comp, ecs_entity_t entity, GFWorld* world) {
-	if (!ecs_has_id(world->raw(), comp, ecs_id(EcsComponent))) {
+	const EcsComponent* comp_ptr = GFComponent::get_component_ptr(world, comp);
+	if (comp_ptr == nullptr) {
 		ERR(nullptr,
 			"Could not instantiate ", get_class_static(), "\n",
-			"ID is not a component"
+			"	Entity ", world->id_to_text(comp), " is not a component"
 		);
 	}
 	Ref<GFComponent> component = from_id_template<GFComponent>(comp, world);
@@ -117,15 +118,17 @@ const EcsMember* GFComponent::get_member_data(String member) {
 	ecs_world_t* raw = get_world()->raw();
 	const char* c_str = member.utf8().get_data();
 
+	ecs_entity_t main_id = get_world()->get_main_id(get_id());
+
 	// Get member ID
-	ecs_entity_t member_id = ecs_lookup_child(raw, get_id(), c_str);
+	ecs_entity_t member_id = ecs_lookup_child(raw, main_id, c_str);
 
 	if (member_id == 0) {
 		ERR(nullptr,
 			"No member named \"",
 			member,
 			"\" found in component \"",
-			ecs_get_name(raw, get_id()),
+			get_world()->id_to_text(get_id()),
 			"\""
 		);
 	}
@@ -181,7 +184,7 @@ Variant GFComponent::member_value_as_type(
 		}
 
 		ERR(nullptr,
-			"Can't convert type ", ecs_get_name(raw, type), " to Variant"
+			"Can't convert type ", get_world()->id_to_text(type), " to Variant"
 		);
 	}
 	case(Variant::Type::BOOL): return Variant( *static_cast<bool*>(ptr) );
@@ -306,6 +309,14 @@ void GFComponent::build_data_from_variant(
 	}
 }
 
+const EcsComponent* GFComponent::get_component_ptr(GFWorld* world, ecs_entity_t id) {
+	return ecs_get(world->raw(), world->get_main_id(id), EcsComponent);
+}
+
+const EcsStruct* GFComponent::get_struct_ptr(GFWorld* world, ecs_entity_t id) {
+	return ecs_get(world->raw(), world->get_main_id(id), EcsStruct);
+}
+
 void GFComponent::build_data_from_members(
 	Array members,
 	void* output,
@@ -314,11 +325,11 @@ void GFComponent::build_data_from_members(
 ) {
 	ecs_world_t* w_raw = world->raw();
 
-	const EcsStruct* struct_data = ecs_get(w_raw, component_id, EcsStruct);
+	const EcsStruct* struct_data = GFComponent::get_struct_ptr(world, component_id);
 	if (struct_data == nullptr) {
 		ERR(/**/,
-			"Could not build data from Variant\n",
-			"Component is not a struct."
+			"Could not build data from Array\n",
+			"	Entity ", world->id_to_text(component_id), " is not a struct."
 		);
 	}
 
diff --git a/cpp/src/component.h b/cpp/src/component.h
index 909d2c4..4926047 100644
--- a/cpp/src/component.h
+++ b/cpp/src/component.h
@@ -6,6 +6,7 @@
 #include "entity.h"
 #include "godot_cpp/core/gdvirtual.gen.inc"
 #include "registerable_entity.h"
+#include "world.h"
 
 #include <flecs.h>
 #include <godot_cpp/classes/ref_counted.hpp>
@@ -51,6 +52,8 @@ namespace godot {
 
 		void build_data_from_variant(Variant, void* output);
 		static void build_data_from_members(Array, void*, ecs_entity_t, GFWorld*);
+		static const EcsComponent* get_component_ptr(GFWorld*, ecs_entity_t);
+		static const EcsStruct* get_struct_ptr(GFWorld*, ecs_entity_t);
 		void set_source_id(ecs_entity_t id);
 
 		static Ref<GFRegisterableEntity> new_internal();
diff --git a/cpp/src/doc_classes/GFEntity.xml b/cpp/src/doc_classes/GFEntity.xml
index 8ad4119..358f239 100644
--- a/cpp/src/doc_classes/GFEntity.xml
+++ b/cpp/src/doc_classes/GFEntity.xml
@@ -24,6 +24,22 @@
 				This method returns [code]self[/code] for chaining.
 			</description>
 		</method>
+		<method name="add_pair" qualifiers="const vararg">
+			<return type="GFEntity" />
+			<param index="0" name="first" type="Variant" />
+			<param index="1" name="second" type="Variant" />
+			<description>
+				Adds component data to the pair of [param first] and [param second] to
+				this entity.
+				The component's type ID is coerced from a [Variant]. To learn more about [Variant] coercion see [method GFWorld.coerce_id].
+				[codeblock]
+				var entity:= GFEntity.spawn()
+				entity.add_pair(GFPosition2D, Vector2(10, 10))
+				entity.get_pair(GFPosition2D).get_vec() == Vector2(10, 10) # true
+				[/codeblock]
+				This method returns [code]self[/code] for chaining.
+			</description>
+		</method>
 		<method name="from" qualifiers="static">
 			<return type="GFEntity" />
 			<param index="0" name="entity" type="Variant" />
@@ -83,6 +99,21 @@
 				[/codeblock]
 			</description>
 		</method>
+		<method name="get_pair">
+			<return type="GFComponent" />
+			<param index="0" name="first" type="Variant" />
+			<param index="1" name="second" type="Variant" />
+			<description>
+				Returns a reference to this entity's component's data in the pair
+				of [param first] and [param second].
+				Returns [code]null[/code] if the entity does not have the [param component] attached or if [param component] is not a component. The component is identified by an ID coerced from a [Variant]. To learn more about [Variant] coercion see [method GFWorld.coerce_id].
+				[codeblock]
+				var entity:= GFEntity.spawn()
+				entity.add_component("glecs/meta/Array")
+				entity.get_component("glecs/meta/Array") != null # true
+				[/codeblock]
+			</description>
+		</method>
 		<method name="get_world">
 			<return type="GFWorld" />
 			<description>
@@ -176,6 +207,24 @@
 				This method returns [code]self[/code] for chaining.
 			</description>
 		</method>
+		<method name="set_pair" qualifiers="const vararg">
+			<return type="GFEntity" />
+			<param index="0" name="first" type="Variant" />
+			<param index="1" name="second" type="Variant" />
+			<description>
+				Sets component data is this entity from the pair of [param first] and
+				[param second].
+				The component's type ID is coerced from a [Variant]. To learn more about [Variant] coercion see [method GFWorld.coerce_id].
+				[codeblock]
+				var start:= GFEntity.spawn().set_name("Start")
+				var entity:= GFEntity.spawn()
+				# Pair will be added if it is not already.
+				entity.set_pair(start, GFPosition2D, Vector2(10, 10))
+				entity.get_pair(start, GFPosition2D).get_vec() == Vector2(10, 10) # true
+				[/codeblock]
+				This method returns [code]self[/code] for chaining.
+			</description>
+		</method>
 		<method name="spawn" qualifiers="static">
 			<return type="GFEntity" />
 			<param index="0" name="world" type="GFWorld" default="null" />
diff --git a/cpp/src/entity.cpp b/cpp/src/entity.cpp
index 7f1f936..bb9fb36 100644
--- a/cpp/src/entity.cpp
+++ b/cpp/src/entity.cpp
@@ -73,7 +73,31 @@ Ref<GFEntity> GFEntity::_add_component(Variant component, Array members) {
 	return this;
 }
 
-Ref<GFEntity> GFEntity::add_pair(Variant first, Variant second, Array members) {
+Ref<GFEntity> GFEntity::add_pair(
+	const Variant** args, GDExtensionInt arg_count, GDExtensionCallError &error
+) {
+	if (arg_count < 2) {
+		// Too few arguments, return with error.
+		error.error = GDExtensionCallErrorType::GDEXTENSION_CALL_ERROR_TOO_FEW_ARGUMENTS;
+		error.argument = arg_count;
+		error.expected = 2;
+		return this;
+	}
+
+	// Parse arguments
+	Array members = Array();
+	members.resize(arg_count);
+	for (int i=0; i != arg_count; i++) {
+		members[i] = *args[i];
+	}
+	Variant first = members.pop_front();
+	Variant sec = members.pop_front();
+
+	_add_pair(first, sec, members);
+
+	return this;
+}
+Ref<GFEntity> GFEntity::_add_pair(Variant first, Variant second, Array members) {
 	GFWorld* w = get_world();
 
 	ecs_entity_t first_id = w->coerce_id(first);
@@ -132,6 +156,12 @@ Ref<GFComponent> GFEntity::get_component(Variant component) {
 	return c;
 }
 
+Ref<GFComponent> GFEntity::get_pair(Variant first, Variant second) {
+	ecs_entity_t first_id = get_world()->coerce_id(first);
+	ecs_entity_t second_id = get_world()->coerce_id(second);
+	return get_component(ecs_pair(first_id, second_id));
+}
+
 Ref<GFEntity> GFEntity::set_component(
 	const Variant** args, GDExtensionInt arg_count, GDExtensionCallError &error
 ) {
@@ -204,6 +234,41 @@ Ref<GFEntity> GFEntity::_set_component(
 	return Ref(this);
 }
 
+Ref<GFEntity> GFEntity::set_pair(
+	const Variant** args, GDExtensionInt arg_count, GDExtensionCallError &error
+) {
+	if (arg_count < 1) {
+		// Too few arguments, return with error.
+		error.error = GDExtensionCallErrorType::GDEXTENSION_CALL_ERROR_TOO_FEW_ARGUMENTS;
+		error.argument = arg_count;
+		error.expected = 1;
+		return this;
+	}
+
+	// Parse arguments
+	Array members = Array();
+	members.resize(arg_count);
+	for (int i=0; i != arg_count; i++) {
+		members[i] = *args[i];
+	}
+	Variant first = members.pop_front();
+	Variant sec = members.pop_front();
+
+	return _set_pair(first, sec, members);
+}
+
+Ref<GFEntity> GFEntity::_set_pair(
+	Variant first,
+	Variant second,
+	Array members
+) {
+	ecs_entity_t first_id = get_world()->coerce_id(first);
+	ecs_entity_t second_id = get_world()->coerce_id(second);
+	_set_component(ecs_pair(first_id, second_id), members);
+
+	return Ref(this);
+}
+
 void GFEntity::delete_() {
 	ecs_delete(get_world()->raw(), get_id());
 }
@@ -327,9 +392,24 @@ void GFEntity::_bind_methods() {
 		godot::ClassDB::bind_vararg_method(METHOD_FLAGS_DEFAULT, StringName("set_component"), &GFEntity::set_component, mi);
 	}
 
-	godot::ClassDB::bind_method(D_METHOD("add_pair", "first", "second", "data"), &GFEntity::add_pair, Array());
+	{
+		MethodInfo mi;
+		mi.arguments.push_back(PropertyInfo(Variant::NIL, "first"));
+		mi.arguments.push_back(PropertyInfo(Variant::NIL, "second"));
+		mi.name = "add_pair";
+		godot::ClassDB::bind_vararg_method(METHOD_FLAGS_DEFAULT, StringName("add_pair"), &GFEntity::add_pair, mi);
+	}
+	{
+		MethodInfo mi;
+		mi.arguments.push_back(PropertyInfo(Variant::NIL, "first"));
+		mi.arguments.push_back(PropertyInfo(Variant::NIL, "second"));
+		mi.name = "set_pair";
+		godot::ClassDB::bind_vararg_method(METHOD_FLAGS_DEFAULT, StringName("set_pair"), &GFEntity::set_pair, mi);
+	}
+
 	godot::ClassDB::bind_method(D_METHOD("add_tag", "tag"), &GFEntity::add_tag);
 	godot::ClassDB::bind_method(D_METHOD("get_component", "component"), &GFEntity::get_component);
+	godot::ClassDB::bind_method(D_METHOD("get_pair", "first", "second"), &GFEntity::get_pair);
 
 	godot::ClassDB::bind_method(D_METHOD("delete"), &GFEntity::delete_);
 
diff --git a/cpp/src/entity.h b/cpp/src/entity.h
index 2cc02ae..d929ef4 100644
--- a/cpp/src/entity.h
+++ b/cpp/src/entity.h
@@ -37,15 +37,18 @@ namespace godot {
 
 		Ref<GFEntity> add_component(const Variant**, GDExtensionInt, GDExtensionCallError&);
 		Ref<GFEntity> _add_component(Variant, Array);
+		Ref<GFEntity> set_component(const Variant**, GDExtensionInt, GDExtensionCallError&);
+		Ref<GFEntity> _set_component(Variant, Array);
+
+		Ref<GFEntity> add_pair(const Variant**, GDExtensionInt, GDExtensionCallError&);
+		Ref<GFEntity> _add_pair(Variant, Variant, Array);
+		Ref<GFEntity> set_pair(const Variant**, GDExtensionInt, GDExtensionCallError&);
+		Ref<GFEntity> _set_pair(Variant, Variant, Array);
 
-		Ref<GFEntity> add_pair(Variant, Variant, Array data);
 		Ref<GFEntity> add_tag(Variant);
 
 		Ref<GFComponent> get_component(Variant);
-
-		Ref<GFEntity> set_component(const Variant**, GDExtensionInt, GDExtensionCallError&);
-		Ref<GFEntity> _set_component(Variant, Array);
-
+		Ref<GFComponent> get_pair(Variant, Variant);
 
 		void delete_();
 
diff --git a/cpp/src/register_types.cpp b/cpp/src/register_types.cpp
index 32c401a..b7f8f91 100644
--- a/cpp/src/register_types.cpp
+++ b/cpp/src/register_types.cpp
@@ -5,6 +5,8 @@
 #include "entity.h"
 #include "gdextension_interface.h"
 #include "godot_cpp/classes/engine.hpp"
+#include "godot_cpp/classes/resource_loader.hpp"
+#include "godot_cpp/variant/utility_functions.hpp"
 #include "module.h"
 #include "observer_builder.h"
 #include "pair.h"
@@ -20,40 +22,53 @@
 using namespace godot;
 
 void initialize_module(ModuleInitializationLevel p_level) {
-	if (p_level == MODULE_INITIALIZATION_LEVEL_EDITOR) {
-		GDExtensionsInterfaceEditorHelpLoadXmlFromUtf8CharsAndLen editor_help_load_xml_from_utf8_chars_and_len = (GDExtensionsInterfaceEditorHelpLoadXmlFromUtf8CharsAndLen)internal::gdextension_interface_get_proc_address("editor_help_load_xml_from_utf8_chars_and_len");
-		editor_help_load_xml_from_utf8_chars_and_len(_doc_data, _doc_data_size);
-	}
-	if (p_level != MODULE_INITIALIZATION_LEVEL_SCENE) {
-		return;
-	}
-
-	godot::ClassDB::register_class<GFWorld>();
+	switch (p_level) {
+        case MODULE_INITIALIZATION_LEVEL_CORE:
+        case MODULE_INITIALIZATION_LEVEL_SERVERS:
+        case MODULE_INITIALIZATION_LEVEL_MAX:
+			break;
+        case MODULE_INITIALIZATION_LEVEL_SCENE:
+			godot::ClassDB::register_class<GFWorld>();
 
-	godot::ClassDB::register_abstract_class<GFEntity>();
-	godot::ClassDB::register_abstract_class<GFPair>();
-	godot::ClassDB::register_class<GFRegisterableEntity>();
-	godot::ClassDB::register_class<GFComponent>();
-	godot::ClassDB::register_class<GFModule>();
+			godot::ClassDB::register_abstract_class<GFEntity>();
+			godot::ClassDB::register_abstract_class<GFPair>();
+			godot::ClassDB::register_class<GFRegisterableEntity>();
+			godot::ClassDB::register_class<GFComponent>();
+			godot::ClassDB::register_class<GFModule>();
 
-	godot::ClassDB::register_abstract_class<GFComponentBuilder>();
-	godot::ClassDB::register_abstract_class<GFQuery>();
-	godot::ClassDB::register_abstract_class<GFQueryIterator>();
+			godot::ClassDB::register_abstract_class<GFComponentBuilder>();
+			godot::ClassDB::register_abstract_class<GFQuery>();
+			godot::ClassDB::register_abstract_class<GFQueryIterator>();
 
-	godot::ClassDB::register_abstract_class<GFQuerylikeBuilder>();
-	godot::ClassDB::register_abstract_class<GFObserverBuilder>();
-	godot::ClassDB::register_abstract_class<GFQueryBuilder>();
-	godot::ClassDB::register_abstract_class<GFSystemBuilder>();
-
-	Engine::get_singleton()->register_singleton(GFWorld::SINGLETON_NAME, memnew(GFWorld));
+			godot::ClassDB::register_abstract_class<GFQuerylikeBuilder>();
+			godot::ClassDB::register_abstract_class<GFObserverBuilder>();
+			godot::ClassDB::register_abstract_class<GFQueryBuilder>();
+			godot::ClassDB::register_abstract_class<GFSystemBuilder>();
+     	   	Engine::get_singleton()->register_singleton(GFWorld::SINGLETON_NAME, memnew(GFWorld));
+			break;
+        case MODULE_INITIALIZATION_LEVEL_EDITOR:
+			GDExtensionsInterfaceEditorHelpLoadXmlFromUtf8CharsAndLen
+				editor_help_load_xml_from_utf8_chars_and_len
+				= (GDExtensionsInterfaceEditorHelpLoadXmlFromUtf8CharsAndLen)
+				internal::gdextension_interface_get_proc_address(
+					"editor_help_load_xml_from_utf8_chars_and_len"
+				);
+			editor_help_load_xml_from_utf8_chars_and_len(_doc_data, _doc_data_size);
+			break;
+	}
 }
 
 void uninitialize_module(ModuleInitializationLevel p_level) {
-	if (p_level != MODULE_INITIALIZATION_LEVEL_SCENE) {
-		return;
+	switch (p_level) {
+        case MODULE_INITIALIZATION_LEVEL_CORE:
+        case MODULE_INITIALIZATION_LEVEL_SERVERS:
+        case MODULE_INITIALIZATION_LEVEL_EDITOR:
+        case MODULE_INITIALIZATION_LEVEL_MAX:
+          break;
+        case MODULE_INITIALIZATION_LEVEL_SCENE:
+     	   Engine::get_singleton()->unregister_singleton(GFWorld::SINGLETON_NAME);
+		   break;
 	}
-
-	Engine::get_singleton()->unregister_singleton(GFWorld::SINGLETON_NAME);
 }
 
 extern "C" {
diff --git a/cpp/src/world.cpp b/cpp/src/world.cpp
index 7a9c948..4563370 100644
--- a/cpp/src/world.cpp
+++ b/cpp/src/world.cpp
@@ -490,17 +490,7 @@ GFWorld::GFWorld() {
 	#undef DEFINE_GD_COMPONENT
 	#undef DEFINE_GD_COMPONENT_WITH_HOOKS
 
-	// Register modules from scripts
-	Engine* engine = Engine::get_singleton();
-	if (engine->has_singleton("_glecs_modules")) {
-		ecs_entity_t prev_scope = ecs_get_scope(raw());
-		ecs_set_scope(raw(), glecs);
-
-		Object* glecs_modules = engine->get_singleton("_glecs_modules");
-		glecs_modules->call("register_modules", this);
-
-		ecs_set_scope(raw(), prev_scope);
-	}
+	_register_modules_from_scripts(0);
 }
 
 GFWorld::~GFWorld() {
@@ -757,6 +747,34 @@ Ref<GFRegisterableEntity> GFWorld::register_script_id_no_user_call(Ref<Script> s
 	return reg_ett;
 }
 
+void GFWorld::_register_modules_from_scripts(int depth=0) {
+	const auto MODULES = "_glecs_modules";
+	// Register modules from scripts
+	Engine* engine = Engine::get_singleton();
+	if (engine->has_singleton(MODULES)) {
+		if (depth != 0) {
+			UtilityFunctions::push_warning("Load modules from scripts was delayed.\n",
+				"	Found \"", MODULES, "\" after", depth, " iteration(s)."
+			);
+		}
+		ecs_entity_t prev_scope = ecs_get_scope(raw());
+		ecs_set_scope(raw(), glecs);
+
+		Object* glecs_modules = engine->get_singleton(MODULES);
+		glecs_modules->call("register_modules", this);
+
+		ecs_set_scope(raw(), prev_scope);
+	} else {
+		if (depth == 10) {
+			UtilityFunctions::push_warning("Failed to load modules from scripts.\n",
+				"	Could not find \"", MODULES, "\"."
+			);
+			return;
+		}
+		call_deferred("_register_modules_from_scripts", depth+1);
+	}
+}
+
 void GFWorld::start_rest_api() {
 	ecs_entity_t rest_id = ecs_lookup_path_w_sep(raw(), 0, "flecs.rest.Rest", ".", "", false);
 	EcsRest rest = (EcsRest)EcsRest();
@@ -770,6 +788,18 @@ ecs_entity_t GFWorld::variant_type_to_id(Variant::Type type) {
 	return GFWorld::glecs_meta_nil + type;
 }
 
+String GFWorld::id_to_text(ecs_entity_t id) {
+	if (ecs_id_is_pair(id)) {
+		return String("(")
+			+ id_to_text(ECS_PAIR_FIRST(id)) + ", "
+			+ id_to_text(ECS_PAIR_SECOND(id)) + ")"
+		;
+	}
+	return String(ecs_get_name(raw(), id))
+		+ "#" + String::num_int64(id)
+	;
+}
+
 Variant::Type GFWorld::id_to_variant_type(ecs_entity_t id) {
 	if (id < GFWorld::glecs_meta_nil) {
 		return godot::Variant::NIL;
@@ -785,6 +815,19 @@ Variant::Type GFWorld::id_to_variant_type(ecs_entity_t id) {
 // --- Unexposed ---
 // ----------------------------------------------
 
+/// If id is a pair then returns the ID that is a component.
+/// Id id is not a pair, then just returns id.
+ecs_entity_t GFWorld::get_main_id(ecs_entity_t id) {
+	if (ECS_IS_PAIR(id)) {
+		ecs_entity_t first = ECS_PAIR_FIRST(id);
+		if (ecs_has_id(raw(), first, FLECS_IDEcsStructID_)) {
+			return first;
+		}
+		return ECS_PAIR_SECOND(id);
+	}
+	return id;
+}
+
 ecs_entity_t GFWorld::get_registered_id(Ref<Script> script) {
 	return registered_entity_ids.get(script, 0);
 }
@@ -1067,6 +1110,8 @@ void GFWorld::_bind_methods() {
 	godot::ClassDB::bind_method(D_METHOD("pair", "first", "second"), &GFWorld::pair);
 	godot::ClassDB::bind_method(D_METHOD("pair_ids", "first", "second"), &GFWorld::pair_ids);
 	godot::ClassDB::bind_method(D_METHOD("progress", "delta"), &GFWorld::progress);
+
+	godot::ClassDB::bind_method(D_METHOD("_register_modules_from_scripts", "depth"), &GFWorld::_register_modules_from_scripts);
 }
 
 // ----------------------------------------------
diff --git a/cpp/src/world.h b/cpp/src/world.h
index 5594eb4..54e5172 100644
--- a/cpp/src/world.h
+++ b/cpp/src/world.h
@@ -45,9 +45,11 @@ namespace godot {
 		ecs_entity_t register_script_id(Ref<Script>);
 		ecs_entity_t register_new_script_id(Ref<Script> script);
 		Ref<GFRegisterableEntity> register_script_id_no_user_call(Ref<Script> script);
+		void _register_modules_from_scripts(int);
 
 		void start_rest_api();
 		static ecs_entity_t variant_type_to_id(Variant::Type);
+		String id_to_text(ecs_entity_t);
 		static Variant::Type id_to_variant_type(ecs_entity_t);
 
 		// **************************************
@@ -100,6 +102,7 @@ namespace godot {
 		static ecs_entity_t glecs_meta_packed_color_array;
 		static ecs_entity_t glecs_meta_packed_vector4_array;
 
+		ecs_entity_t get_main_id(ecs_entity_t);
 		/// Returns the ID which was registered with the given Script.
 		/// Returns 0 if the entity has no registered script.
 		ecs_entity_t get_registered_id(Ref<Script> script);
diff --git a/gd/modules.gd b/gd/modules.gd
index 33662bc..b4e7edb 100644
--- a/gd/modules.gd
+++ b/gd/modules.gd
@@ -8,9 +8,9 @@ const MODULES:= [
 	"./rendering/rendering.gd",
 ]
 
-static var _register_self_singleton = (func():
+static var x:= (func():
 	Engine.register_singleton("_glecs_modules", _GlecsModules)
-	).call()
+).call()
 
 static func register_modules(w:GFWorld) -> void:
 	var path:= (_GlecsModules as Script).resource_path.path_join("../")
diff --git a/plugin.gd b/plugin.gd
index 7873222..2ba41d4 100644
--- a/plugin.gd
+++ b/plugin.gd
@@ -9,3 +9,4 @@ func _enter_tree() -> void:
 
 func _exit_tree() -> void:
 	remove_autoload_singleton("_glecs_modules")
+	Engine.unregister_singleton("_glecs_modules")
diff --git a/unittests/test_relations.gd b/unittests/test_relations.gd
index 7c08f8e..3b40700 100644
--- a/unittests/test_relations.gd
+++ b/unittests/test_relations.gd
@@ -3,38 +3,77 @@ extends GutTest
 
 var world:GFWorld
 
-func before_all():
+func before_each():
 	world = GFWorld.new()
 
-func after_all():
+func after_each():
 	world.free()
 
 #region Tests
 
-#func test_bools():
-	#var apple:= GFEntity.spawn(world) \
-		#.set_name("Apple")
-#
-	#GFEntity.spawn(world) \
-		#.set_name("Eats")
-#
-	#var man:= GFEntity.spawn(world) \
-		#.set_name("Man") \
-		#.add_pair("Eats", apple)
-#
-	#var cow:= GFEntity.spawn(world) \
-		#.set_name("Cow")
-	#var grass:= GFEntity.spawn(world) \
-		#.set_name("Grass")
-	#cow.add_pair("Eats", grass)
-#
-	#world.progress(0.0)
-#
-	## TODO: Test querying for relations
-	#world.query_builder().build()
-#
-	#man.delete()
-	#apple.delete()
+func test_add_and_set_pairs() -> void:
+	var eats:= GFEntity.spawn(world).set_name("Eats")
+	var grass:= GFEntity.spawn(world).set_name("Grass")
+	
+	var e:= GFEntity.spawn(world)
+	
+	e.add_pair("Eats", GFRotation2D, 3.0)
+	assert_almost_eq(
+		e.get_component(eats.pair(GFRotation2D)).get_angle(),
+		3.0,
+		0.01,
+	)
+	
+	e.set_pair(eats, GFRotation2D, 1.5)
+	e.add_pair(GFRotation2D, eats, 1.1)
+	
+	assert_almost_eq(
+		e.get_pair(eats, GFRotation2D).get_angle(),
+		1.5,
+		0.01,
+	)
+	assert_almost_eq(
+		e.get_pair(GFRotation2D, eats).get_angle(),
+		1.1,
+		0.01,
+	)
+
+func test_basic_query():
+	var eats:= GFEntity.spawn(world) \
+		.set_name("Eats")
+	var apple:= GFEntity.spawn(world) \
+		.set_name("Apple")
+	var grass:= GFEntity.spawn(world) \
+		.set_name("Grass")
+	var man:= GFEntity.spawn(world) \
+		.set_name("Man") \
+		.add_pair("Eats", apple)
+	var cow:= GFEntity.spawn(world) \
+		.set_name("Cow") \
+		.add_pair("Eats", grass)
+
+	var grass_eater_iter:= world.query_builder() \
+		.with(eats.pair(grass)) \
+		.build() as GFQuery
+	var grass_eater_count:= 0
+	for _x in grass_eater_iter.iterate():
+		grass_eater_count += 1
+	assert_eq(grass_eater_count, 1)
+	
+	var eater_iter:= world.query_builder() \
+		.with(eats.pair("flecs/core/*")) \
+		.build() as GFQuery
+	var eater_count:= 0
+	for _x in eater_iter.iterate():
+		eater_count += 1
+	assert_eq(eater_count, 2)
+
+func test_is_pair():
+	var likes = GFEntity.spawn(world).set_name("Likes")
+	var jill = GFEntity.spawn(world).set_name("Jill")
+	var likes_jill = likes.pair(jill)
+	
+	assert_true(likes_jill.is_pair())
 
 #endregion