Refactor ModuleManager and built-in modules

- Create a minimal Flecs world (no default addon module imports)
- Wrap all the official Flecs addon modules as [BuiltIn] modules
- Add IModuleImport for [BuiltIn] modules
- Rename IModuleInitializer to IModuleLifetime
- Rename IModule.Initialize to .OnEnable
- Overhaul ModuleManager to use entities and rules
- Use ModuleManager.Import for built-in modules
- Add gaemstone.Doc.Tag to represent tag-like components
- Overhaul EntityInspector to use new features

src/Immersion/Program.cs

@@ -23,8 +23,12 @@ var universe = new Universe<Program>();
 var world    = universe.World;
 
 // TODO: Figure out a nice way to get rid of "compile errors" here.
-// FIXME: universe.Modules.Register<gaemstone.Flecs.Systems.Monitor>();
+universe.Modules.Import<gaemstone.Flecs.Timer>();
-universe.Modules.Register<gaemstone.Flecs.Systems.Rest>();
+universe.Modules.Import<gaemstone.Flecs.Script>();
+universe.Modules.Import<gaemstone.Flecs.Rest>();
+universe.Modules.Import<gaemstone.Flecs.Monitor>();
+universe.Modules.Import<gaemstone.Flecs.Units>();
+universe.Modules.Import<gaemstone.Flecs.Metrics>();
 
 var window = Window.Create(WindowOptions.Default with {
 	Title = "gæmstone",
@@ -57,9 +61,9 @@ universe.Modules.Register<gaemstone.Client.Systems.EntityInspector>();
 universe.Modules.Register<gaemstone.Client.Components.CameraComponents>();
 universe.Modules.Register<gaemstone.Client.Systems.FreeCameraController>();
 
-foreach (var module in universe.Modules)
+using (var disabledModules = world.Filter(new("ModuleInfo, Disabled")))
-	if (!module.IsInitialized) throw new InvalidOperationException(
+	foreach (var module in disabledModules.Iter().GetAllEntities())
-		$"Module '{module.Entity.Path}' is not initialized");
+		throw new InvalidOperationException($"Module '{module.Path}' is not ednbled");
 
 // Initialize Canvas and GameWindow singletons with actual values.
 world.Entity<Canvas>().Set(new Canvas(Silk.NET.OpenGL.ContextSourceExtensions.CreateOpenGL(window)));

src/gaemstone.Client/Systems/EntityInspector.cs

@@ -7,7 +7,6 @@ using gaemstone.ECS;
 using gaemstone.Flecs;
 using ImGuiNET;
 using static gaemstone.Client.Systems.ImGuiManager;
-using Icon = gaemstone.Client.Utility.ForkAwesome;
 using ImGuiInternal = ImGuiNET.Internal.ImGui;
 
 namespace gaemstone.Client.Systems;
@@ -15,7 +14,6 @@ namespace gaemstone.Client.Systems;
 [Module]
 [DependsOn<gaemstone.Client.Systems.ImGuiManager>]
 public partial class EntityInspector
-	: IModuleInitializer
 {
 	[Tag]
 	public struct InspectorWindow {  }
@@ -54,32 +52,49 @@ public partial class EntityInspector
 	}
 
 	[Component]
-	public struct DocPriority { public float Value; }
+	public record struct Priority(float Value);
 
 	[Component]
-	public struct DocIcon { public char Value; }
+	public record struct Icon(char Value);
 
 
-	private const string DefaultWindowTitle = "Inspector Gadget";
+	[Path("/flecs/core/Module")]
+	// [Doc(Color = "#FFE4B2")]
+	[Add<Doc.DisplayType>, Set<Priority>(0), Set<Icon>(ForkAwesome.Archive)]
+	public struct Module {  }
 
-	public static void Initialize<T>(Entity<T> module)
+	[Path("/flecs/system/System")]
-	{
+	// [Doc(Color = "#FFB2B2")]
-		void SetDocInfo(string path, float priority, string icon, float r, float g, float b)
+	[Add<Doc.DisplayType>, Set<Priority>(1), Set<Icon>(ForkAwesome.Cog)]
-			=> module.World.LookupPathOrThrow(path)
+	public struct System {  }
-				.Add<Doc.DisplayType>()
+
-				.Set(new DocPriority { Value = priority })
+	[Path("/flecs/core/Observer")]
-				.Set(new DocIcon { Value = icon[0] })
+	// [Doc(Color = "#FFCCCC")]
-				.SetDocColor(Color.FromRGB(r, g, b).ToHexString());
+	[Add<Doc.DisplayType>, Set<Priority>(2), Set<Icon>(ForkAwesome.Eye)]
-
+	public struct Observer {  }
-		SetDocInfo("/flecs/core/Module"      , 0 , Icon.Archive      , 1.0f, 0.9f, 0.7f);
+
-		SetDocInfo("/flecs/system/System"    , 1 , Icon.Cog          , 1.0f, 0.7f, 0.7f);
+	[Path("/gaemstone/Doc/Relation")]
-		SetDocInfo("/flecs/core/Observer"    , 2 , Icon.Eye          , 1.0f, 0.8f, 0.8f);
+	// [Doc(Color = "#B2FFCC")]
-		SetDocInfo("/gaemstone/Doc/Relation" , 3 , Icon.ShareAlt     , 0.7f, 1.0f, 0.8f);
+	[Add<Doc.DisplayType>, Set<Priority>(3), Set<Icon>(ForkAwesome.ShareAlt)]
-		SetDocInfo("/flecs/core/Component"   , 4 , Icon.PencilSquare , 0.6f, 0.6f, 1.0f);
+	public struct Relation {  }
-		// TODO: Handle tags like Flecs does.
+
-		SetDocInfo("/flecs/core/Tag"         , 5 , Icon.Tag          , 0.7f, 0.8f, 1.0f);
+	[Path("/flecs/core/Component")]
-		SetDocInfo("/flecs/core/Prefab"      , 6 , Icon.Cube         , 0.9f, 0.8f, 1.0f);
+	// [Doc(Color = "#9999FF")]
-	}
+	[Add<Doc.DisplayType>, Set<Priority>(4), Set<Icon>(ForkAwesome.PencilSquare)]
+	public struct Component {  }
+
+	[Path("/gaemstone/Doc/Tag")]
+	// [Doc(Color = "#B2CCFF")]
+	[Add<Doc.DisplayType>, Set<Priority>(5), Set<Icon>(ForkAwesome.Tag)]
+	public struct Tag {  }
+
+	[Path("/flecs/core/Prefab")]
+	// [Doc(Color = "#E4CCFF")]
+	[Add<Doc.DisplayType>, Set<Priority>(6), Set<Icon>(ForkAwesome.Cube)]
+	public struct Prefab {  }
+
+
+	private const string DefaultWindowTitle = "Inspector Gadget";
 
 
 	[System]
@@ -87,10 +102,10 @@ public partial class EntityInspector
 	{
 		var hasAnyInspector = false;
 		var inspectorWindow = world.Entity<InspectorWindow>();
-		foreach (var entity in Iterator<T>.FromTerm(world, new(inspectorWindow)))
+		foreach (var entity in world.Term(new(inspectorWindow)))
 			{ hasAnyInspector = true; break; }
 
-		if (ImGuiUtility.UIButton(0, Icon.Search, DefaultWindowTitle, hasAnyInspector))
+		if (ImGuiUtility.UIButton(0, ForkAwesome.Search, DefaultWindowTitle, hasAnyInspector))
 			NewEntityInspectorWindow(world);
 	}
 
@@ -104,7 +119,7 @@ public partial class EntityInspector
 		ImGui.SetNextWindowSize(new(fontSize * 40, fontSize * 25), ImGuiCond.Appearing);
 		ImGui.PushFont(ImGui.GetIO().Fonts.Fonts[1]);
 		var title = window.GetDocName() ?? DefaultWindowTitle;
-		if (ImGui.Begin($"{Icon.Search} {title}###{window.NumericId}",
+		if (ImGui.Begin($"{ForkAwesome.Search} {title}###{window.NumericId}",
 		                ref isOpen, ImGuiWindowFlags.NoScrollbar)) {
 			ImGui.PushFont(ImGui.GetIO().Fonts.Fonts[0]);
 
@@ -132,9 +147,9 @@ public partial class EntityInspector
 			ImGui.TableNextColumn();
 			ImGui.BeginChild("EntityView", new(-float.Epsilon, -float.Epsilon));
 			if (!ImGui.BeginTabBar("Tabs")) return;
-			Tab($"{Icon.PencilSquare} Components", ComponentsTab);
+			Tab($"{ForkAwesome.PencilSquare} Components", ComponentsTab);
-			Tab($"{Icon.ShareAlt} References", ReferencesTab);
+			Tab($"{ForkAwesome.ShareAlt} References", ReferencesTab);
-			Tab($"{Icon.InfoCircle} Documentation", DocumentationTab);
+			Tab($"{ForkAwesome.InfoCircle} Documentation", DocumentationTab);
 			ImGui.EndTabBar();
 			ImGui.EndChild();
 
@@ -157,9 +172,9 @@ public partial class EntityInspector
 
 	private static void ActionBarAndPath<T>(Entity<T> window, History? history, Entity<T>? selected)
 	{
-		static bool IconButtonWithToolTip(string icon, string tooltip, bool enabled = true) {
+		static bool IconButtonWithToolTip(char icon, string tooltip, bool enabled = true) {
 			if (!enabled) ImGui.BeginDisabled();
-			var clicked = ImGui.Button(icon);
+			var clicked = ImGui.Button(icon.ToString());
 			if (!enabled) ImGui.EndDisabled();
 			if (ImGui.IsItemHovered(ImGuiHoveredFlags.AllowWhenDisabled))
 				ImGui.SetTooltip(tooltip);
@@ -174,22 +189,22 @@ public partial class EntityInspector
 
 		ImGui.TableNextColumn();
 		var hasExpanded = window.Has<Expanded, Core.Wildcard>();
-		if (IconButtonWithToolTip(Icon.Outdent, "Collapse all items in the Explorer View", hasExpanded))
+		if (IconButtonWithToolTip(ForkAwesome.Outdent, "Collapse all items in the Explorer View", hasExpanded))
 			window.Remove<Expanded, Core.Wildcard>();
 
 		if (history != null) {
 			var hasPrev = ((selected != null) ? history.Current?.Prev : history.Current) != null;
 			var hasNext = history.Current?.Next != null;
 			ImGui.SameLine();
-			if (IconButtonWithToolTip(Icon.ArrowLeft, "Go to the previously viewed entity", hasPrev))
+			if (IconButtonWithToolTip(ForkAwesome.ArrowLeft, "Go to the previously viewed entity", hasPrev))
 				GoToPrevious(window, history, selected);
 			ImGui.SameLine();
-			if (IconButtonWithToolTip(Icon.ArrowRight, "Go to the next viewed entity", hasNext))
+			if (IconButtonWithToolTip(ForkAwesome.ArrowRight, "Go to the next viewed entity", hasNext))
 				GoToNext(window, history);
 		}
 
 		ImGui.SameLine();
-		if (IconButtonWithToolTip(Icon.Crosshairs, "Scroll to the current entity in the Explorer View", (selected != null)))
+		if (IconButtonWithToolTip(ForkAwesome.Crosshairs, "Scroll to the current entity in the Explorer View", (selected != null)))
 			window.Add<ScrollToSelected>();
 
 		ImGui.TableNextColumn();
@@ -197,22 +212,22 @@ public partial class EntityInspector
 		PathInput(window, history, selected, availableWidth);
 
 		ImGui.TableNextColumn();
-		if (IconButtonWithToolTip(Icon.PlusCircle, "Create a new child entity", (selected != null)))
+		if (IconButtonWithToolTip(ForkAwesome.PlusCircle, "Create a new child entity", (selected != null)))
 			SetSelected(window, history, selected?.NewChild().Build());
 
 		ImGui.SameLine();
-		if (IconButtonWithToolTip(Icon.Pencil, "Rename the current entity", false && (selected != null)))
+		if (IconButtonWithToolTip(ForkAwesome.Pencil, "Rename the current entity", false && (selected != null)))
 			{  } // TODO: Implement this!
 
 		ImGui.SameLine();
 		var isDisabled = (selected?.IsDisabled == true);
-		var icon    = !isDisabled ? Icon.BellSlash : Icon.Bell;
+		var icon    = !isDisabled ? ForkAwesome.BellSlash : ForkAwesome.Bell;
 		var tooltip = $"{(!isDisabled ? "Disable" : "Enable")} the current entity";
 		if (IconButtonWithToolTip(icon, tooltip, (selected != null)))
 			{ if (isDisabled) selected?.Enable(); else selected?.Disable(); }
 
 		ImGui.SameLine();
-		if (IconButtonWithToolTip(Icon.Trash, "Delete the current entity", (selected != null))) {
+		if (IconButtonWithToolTip(ForkAwesome.Trash, "Delete the current entity", (selected != null))) {
 			// TODO: Delete history for deleted entity?
 			SetSelected(window, history, selected?.Parent);
 			selected?.Delete(); // TODO: Confirmation dialog?
@@ -361,9 +376,9 @@ public partial class EntityInspector
 		var expId = world.Entity<Expanded>().NumericId;
 		List<IExplorerEntry> GetEntries(Entity? parent) {
 			var result = new List<IExplorerEntry>();
-			using var rule = new Rule<T>(world, new(
+			using var rule = world.Rule(new(
 				  $"(ChildOf, {parent?.NumericId ?? 0})"  // Must be child of parent, or root entity.
-				+ $",?{expId}({window.NumericId}, $This)" // Whether entity is expanded in explorer view.
+				+ $",?{expId}({window.NumericId}, $this)" // Whether entity is expanded in explorer view.
 				+ $",?Disabled"                           // Don't filter out disabled entities.
 			));
 			foreach (var iter in rule.Iter()) {
@@ -471,13 +486,13 @@ public partial class EntityInspector
 		var ChildOf  = world.Entity<Core.ChildOf>();
 		var Wildcard = world.Entity<Core.Wildcard>();
 
-		if (ImGui.CollapsingHeader($"As {Icon.Tag} Component", ImGuiTreeNodeFlags.DefaultOpen))
+		if (ImGui.CollapsingHeader($"As {ForkAwesome.Tag} Component", ImGuiTreeNodeFlags.DefaultOpen))
-			foreach (var iter in Iterator<T>.FromTerm(world, new(selected)))
+			foreach (var iter in world.Term(new(selected)))
 				for (var i = 0; i < iter.Count; i++)
 					RenderEntity(window, history, iter.Entity(i));
 
-		if (ImGui.CollapsingHeader($"As {Icon.ShareAlt} Relation", ImGuiTreeNodeFlags.DefaultOpen))
+		if (ImGui.CollapsingHeader($"As {ForkAwesome.ShareAlt} Relation", ImGuiTreeNodeFlags.DefaultOpen))
-			foreach (var iter in Iterator<T>.FromTerm(world, new(selected, Wildcard))) {
+			foreach (var iter in world.Term(new(selected, Wildcard))) {
 				var id = iter.FieldId(1);
 				if (id.AsPair() is not (Entity<T> relation, Entity<T> target)) throw new InvalidOperationException();
 				if (relation == ChildOf) continue; // Hide ChildOf relations.
@@ -489,8 +504,8 @@ public partial class EntityInspector
 				}
 			}
 
-		if (ImGui.CollapsingHeader($"As {Icon.Bullseye} Target", ImGuiTreeNodeFlags.DefaultOpen))
+		if (ImGui.CollapsingHeader($"As {ForkAwesome.Bullseye} Target", ImGuiTreeNodeFlags.DefaultOpen))
-			foreach (var iter in Iterator<T>.FromTerm(world, new(Wildcard, selected))) {
+			foreach (var iter in world.Term(new(Wildcard, selected))) {
 				var id = iter.FieldId(1);
 				if (id.AsPair() is not (Entity<T> relation, Entity<T> target)) throw new InvalidOperationException();
 				if (relation == ChildOf) continue; // Hide ChildOf relations.
@@ -521,7 +536,7 @@ public partial class EntityInspector
 			if (fill) ImGui.SetNextItemWidth(-float.Epsilon);
 		}
 
-		Column($"{Icon.Tag} Display Name", """
+		Column($"{ForkAwesome.Tag} Display Name", """
 			A display name for this entity.
 			Names in the entity hierarchy must be unique within the parent entity,
 			This doesn't apply to display names - they are mostly informational.
@@ -532,7 +547,7 @@ public partial class EntityInspector
 			selected?.SetDocName((name.Length > 0) ? name : null);
 		if (!hasSelected) ImGui.EndDisabled();
 
-		Column($"{Icon.Comment} Description",
+		Column($"{ForkAwesome.Comment} Description",
 			"A brief description of this entity.");
 		if (!hasSelected) ImGui.BeginDisabled();
 		var brief = selected?.GetDocBrief() ?? "";
@@ -540,7 +555,7 @@ public partial class EntityInspector
 			selected?.SetDocBrief((brief.Length > 0) ? brief : null);
 		if (!hasSelected) ImGui.EndDisabled();
 
-		Column($"{Icon.FileText} Documentation", """
+		Column($"{ForkAwesome.FileText} Documentation", """
 			A detailed description, or full documentation, of this entity's purpose and behaviors.
 			It's encouraged to use multiple paragraphs and markdown formatting if necessary.
 			""");
@@ -556,7 +571,7 @@ public partial class EntityInspector
 			selected?.SetDocDetail((detail.Length > 0) ? detail : null);
 		if (!hasSelected) ImGui.EndDisabled();
 
-		Column($"{Icon.Link} Link", """
+		Column($"{ForkAwesome.Link} Link", """
 			A link to a website relating to this entity, such as
 			a module's repository, or further documentation.
 			""");
@@ -566,7 +581,7 @@ public partial class EntityInspector
 			selected?.SetDocLink((link.Length > 0) ? link : null);
 		if (!hasSelected) ImGui.EndDisabled();
 
-		Column($"{Icon.PaintBrush} Color", """
+		Column($"{ForkAwesome.PaintBrush} Color", """
 			A custom color to represent this entity.
 			Used in the entity inspector's explorer view.
 			""", false);
@@ -649,7 +664,7 @@ public partial class EntityInspector
 		var world = entity.World;
 		var component = world.Entity<Core.Component>();
 
-		var rule = (Rule<T>)(_findDisplayTypeRule ??= new Rule<T>(world, new(
+		var rule = (Rule<T>)(_findDisplayTypeRule ??= world.Rule(new(
 			$"$Type, gaemstone.Doc.DisplayType($Type)")));
 		var typeVar = rule.Variables["Type"]!;
 
@@ -660,7 +675,7 @@ public partial class EntityInspector
 				var type = iter.GetVar(typeVar);
 				if ((type == component) && (entity.GetOrNull<Core.Component>(component)?.Size == 0))
 					type = world.Entity<Core.Tag>();
-				var priority = type?.GetOrNull<DocPriority>()?.Value ?? float.MaxValue;
+				var priority = type?.GetOrNull<Priority>()?.Value ?? float.MaxValue;
 				if (priority <= curPriority) { curType = type; curPriority = priority; }
 			}
 
@@ -705,8 +720,8 @@ public partial class EntityInspector
 		if (!ImGui.IsRectVisible(pos, pos + dummySize)) { ImGui.Dummy(dummySize); return; }
 
 		var (displayType, _) = FindDisplayType(entity);
-		var docColor = Color.TryParseHex(entity.GetDocColor())       ?? Color.TryParseHex(displayType?.GetDocColor());
+		var docColor = Color.TryParseHex(entity.GetDocColor())    ?? Color.TryParseHex(displayType?.GetDocColor());
-		var docIcon  = entity.GetOrNull<DocIcon>()?.Value.ToString() ?? displayType?.GetOrNull<DocIcon>()?.Value.ToString();
+		var docIcon  = entity.GetOrNull<Icon>()?.Value.ToString() ?? displayType?.GetOrNull<Icon>()?.Value.ToString();
 		var docName  = entity.GetDocName(false);
 
 		var isDisabled  = entity.IsDisabled;

src/gaemstone.Client/Systems/InputManager.cs

@@ -1,7 +1,6 @@
 using System;
 using System.Linq;
 using System.Numerics;
-using System.Runtime.CompilerServices;
 using gaemstone.ECS;
 using gaemstone.Flecs;
 using Silk.NET.Input;

src/gaemstone.Client/Systems/Renderer.cs

@@ -95,7 +95,7 @@ public partial class Renderer
 		var cameraMatrix = invertedTransform * cameraProjection;
 		GL.UniformMatrix4(_cameraMatrixUniform, 1, false, in cameraMatrix.M11);
 
-		var rule = (Rule<T>)(_renderEntityRule ??= new Rule<T>(world, new("""
+		var rule = (Rule<T>)(_renderEntityRule ??= world.Rule(new("""
 			[in] GlobalTransform,
 			(Mesh, $mesh), [in] MeshHandle($mesh),
 			?(Texture, $tex), [in] ?TextureHandle($tex)

src/gaemstone.Client/Utility/ImGuiUtility.cs

@@ -6,8 +6,13 @@ namespace gaemstone.Client.Utility;
 
 public static class ImGuiUtility
 {
+	public static bool UIButtonToggle(int index, char icon, string tooltip, ref bool enabled)
+		=> UIButtonToggle(index, icon.ToString(), tooltip, ref enabled);
 	public static bool UIButtonToggle(int index, string label, string tooltip, ref bool enabled)
 		{ if (UIButton(index, label, tooltip, enabled)) enabled = !enabled; return enabled; }
+
+	public static bool UIButton(int index, char icon, string tooltip, bool active)
+		=> UIButton(index, icon.ToString(), tooltip, active);
 	public static bool UIButton(int index, string label, string tooltip, bool active)
 	{
 		var start = new Vector2(4, 4);

src/gaemstone.ECS

@@ -1 +1 @@
-Subproject commit c575046a61620434e7ee01679ce86bf0beb0f700
+Subproject commit 063fb40c5c56adbd5bedd39045f1b896b4e420c3

src/gaemstone.SourceGen/ModuleGenerator.cs

@@ -120,7 +120,7 @@ public class ModuleGenerator
 		sb.AppendLine();
 
 		sb.AppendLine($$"""
-				static void IModule.Initialize<T>(Entity<T> module)
+				static void IModule.OnEnable<T>(Entity<T> module)
 				{
 					var world = module.World;
 			""");
@@ -134,12 +134,25 @@ public class ModuleGenerator
 
 		// TODO: Can BuiltIn modules have systems and such?
 
-		if (module.HasInitializer)
+		if (module.HasLifetimeInterface)
-			sb.AppendLine("\t\tInitialize(module);");
+			sb.AppendLine("\t\tOnEnabled(module);");
 
-		sb.AppendLine("\t}");
+		sb.AppendLine($$"""
+				}
+
+				static void IModule.OnDisable<T>(Entity<T> module)
+				{
+			""");
 
-		sb.AppendLine("}");
+		if (module.IsBuiltIn)
+			sb.AppendLine("\t\tthrow new global::System.InvalidOperationException();");
+		if (module.HasLifetimeInterface)
+			sb.AppendLine("\t\tOnDisabled(module);");
+
+		sb.AppendLine($$"""
+				}
+			}
+			""");
 	}
 
 	private void AppendEntityRegistration(

src/gaemstone.SourceGen/Structure/MethodEntityInfo.cs

@@ -88,7 +88,7 @@ public class MethodEntityInfo : BaseEntityInfo
 				param.TermIndex = termIndex++;
 
 		// See if we have any [DependsOn<...>] attributes for this system.
-		// If not, ModuleGenerator will add [DependsOn<Flecs.Pipeline.OnUpdate>].
+		// If not, ModuleGenerator will add [DependsOn<gaemstone.Flecs.Pipeline.OnUpdate>].
 		HasPhaseSet = IsSystem && RelationsToAdd.Any(entry => entry.Relation
 			.GetFullName(FullNameStyle.NoGeneric) == "gaemstone.ECS.DependsOnAttribute");
 

src/gaemstone.SourceGen/Structure/ModuleEntityInfo.cs

@@ -10,7 +10,7 @@ namespace gaemstone.SourceGen.Structure;
 public class ModuleEntityInfo : TypeEntityInfo
 {
 	public bool IsPartial { get; }
-	public bool HasInitializer { get; }
+	public bool HasLifetimeInterface { get; }
 
 	public ModuleEntityInfo(ISymbol symbol)
 		: base(symbol)
@@ -18,8 +18,8 @@ public class ModuleEntityInfo : TypeEntityInfo
 		var classDecl = (TypeDeclarationSyntax)Symbol.DeclaringSyntaxReferences.First().GetSyntax();
 		IsPartial = classDecl.Modifiers.Any(t => t.IsKind(SyntaxKind.PartialKeyword));
 
-		HasInitializer = Symbol.AllInterfaces.Any(i =>
+		HasLifetimeInterface = Symbol.AllInterfaces.Any(i =>
-			i.GetFullName(FullNameStyle.NoGeneric) == "gaemstone.ECS.IModuleInitializer");
+			i.GetFullName(FullNameStyle.NoGeneric) == "gaemstone.ECS.IModuleLifetime");
 
 		IsBuiltIn = Has("BuiltIn");
 	}

src/gaemstone/Doc.cs

@@ -13,6 +13,14 @@ public partial class Doc
 	[Tag]
 	public struct Relation {  }
 
+	/// <summary>
+	/// Tags are just <see cref="Flecs.Core.Component"/>s with 0 size.
+	/// This functions as a special entity that holds the appearance for tags.
+	/// Not related to <see cref="Flecs.Core.Tag"/> in any way.
+	/// </summary>
+	[Tag]
+	public struct Tag {  }
+
 
 	// TODO: These need to actually be read at some point.
 

src/gaemstone/ECS/Module.cs

@@ -6,13 +6,27 @@ namespace gaemstone.ECS;
 [AttributeUsage(AttributeTargets.Class | AttributeTargets.Struct)]
 public class ModuleAttribute : SingletonAttribute {  }
 
+public interface IModuleLifetime
+{
+	void OnEnable<TContext>(Entity<TContext> module);
+
+	void OnDisable<TContext>(Entity<TContext> module);
+}
+
+
 [AttributeUsage(AttributeTargets.Class)]
 public class BuiltInAttribute : Attribute {  }
 
+public interface IModuleImport
+{
+	static abstract Entity<TContext> Import<TContext>(World<TContext> world);
+}
+
 
 /// <summary>
 /// A concrete implementation of this interface is generated by a source
 /// generator for each type marked as <see cref="ModuleAttribute"/>.
+/// (Do not implement this yourself.)
 /// </summary>
 public interface IModule
 {
@@ -22,10 +36,8 @@ public interface IModule
 
 	static abstract IReadOnlyList<string> Dependencies { get; }
 
-	static abstract void Initialize<TContext>(Entity<TContext> module);
-}
 
-public interface IModuleInitializer
+	static abstract void OnEnable<TContext>(Entity<TContext> module);
-{
+
-	static abstract void Initialize<TContext>(Entity<TContext> module);
+	static abstract void OnDisable<TContext>(Entity<TContext> module);
 }

src/gaemstone/Flecs/Core.cs

@@ -4,6 +4,7 @@ namespace gaemstone.Flecs;
 
 [BuiltIn, Module, Path("/flecs/core")]
 public partial class Core
+	: IModuleImport
 {
 	// Entity Tags
 
@@ -105,4 +106,8 @@ public partial class Core
 		public static implicit operator string?(Identifier id)
 			=> id.ToString();
 	}
+
+
+	static Entity<T> IModuleImport.Import<T>(World<T> world)
+		=> world.LookupPathOrThrow("/flecs/core");
 }

src/gaemstone/Flecs/CoreDoc.cs

@@ -0,0 +1,25 @@
+using System.Runtime.InteropServices;
+using gaemstone.ECS;
+using gaemstone.ECS.Utility;
+using static flecs_hub.flecs;
+
+namespace gaemstone.Flecs;
+
+[BuiltIn, Module, Path("/flecs/coredoc")]
+[DependsOn<gaemstone.Flecs.Meta>]
+[DependsOn<gaemstone.Flecs.Doc>]
+public unsafe partial class CoreDoc
+	: IModuleImport
+{
+	static Entity<T> IModuleImport.Import<T>(World<T> world)
+	{
+		using var alloc = TempAllocator.Use();
+		return Entity<T>.GetOrThrow(world, new(ecs_import_c(world,
+			new() { Data = new() { Pointer = &CoreDocImport } },
+			alloc.AllocateCString("FlecsCoreDoc"))));
+	}
+
+	[UnmanagedCallersOnly]
+	private static void CoreDocImport(ecs_world_t* world)
+		=> FlecsCoreDocImport(world);
+}

src/gaemstone/Flecs/Doc.cs

@@ -6,7 +6,8 @@ using static flecs_hub.flecs;
 namespace gaemstone.Flecs;
 
 [BuiltIn, Module, Path("/flecs/doc")]
-public partial class Doc
+public unsafe partial class Doc
+	: IModuleImport
 {
 	[Tag] public struct Brief {  }
 	[Tag] public struct Detail {  }
@@ -23,6 +24,19 @@ public partial class Doc
 		public static implicit operator string?(Description desc)
 			=> desc.ToString();
 	}
+
+
+	static Entity<T> IModuleImport.Import<T>(World<T> world)
+	{
+		using var alloc = TempAllocator.Use();
+		return Entity<T>.GetOrThrow(world, new(ecs_import_c(world,
+			new() { Data = new() { Pointer = &DocImport } },
+			alloc.AllocateCString("FlecsDoc"))));
+	}
+
+	[UnmanagedCallersOnly]
+	private static void DocImport(ecs_world_t* world)
+		=> FlecsDocImport(world);
 }
 
 public static unsafe class DocExtensions

src/gaemstone/Flecs/Meta.cs

@@ -0,0 +1,23 @@
+using System.Runtime.InteropServices;
+using gaemstone.ECS;
+using gaemstone.ECS.Utility;
+using static flecs_hub.flecs;
+
+namespace gaemstone.Flecs;
+
+[BuiltIn, Module, Path("/flecs/meta")]
+public unsafe partial class Meta
+	: IModuleImport
+{
+	static Entity<T> IModuleImport.Import<T>(World<T> world)
+	{
+		using var alloc = TempAllocator.Use();
+		return Entity<T>.GetOrThrow(world, new(ecs_import_c(world,
+			new() { Data = new() { Pointer = &MetaImport } },
+			alloc.AllocateCString("FlecsMeta"))));
+	}
+
+	[UnmanagedCallersOnly]
+	private static void MetaImport(ecs_world_t* world)
+		=> FlecsMetaImport(world);
+}

src/gaemstone/Flecs/Metrics.cs

@@ -0,0 +1,26 @@
+using System.Runtime.InteropServices;
+using gaemstone.ECS;
+using gaemstone.ECS.Utility;
+using static flecs_hub.flecs;
+
+namespace gaemstone.Flecs;
+
+[BuiltIn, Module, Path("/flecs/timer")]
+[DependsOn<gaemstone.Flecs.Pipeline>]
+[DependsOn<gaemstone.Flecs.Meta>]
+[DependsOn<gaemstone.Flecs.Units>]
+public unsafe partial class Metrics
+	: IModuleImport
+{
+	static Entity<T> IModuleImport.Import<T>(World<T> world)
+	{
+		using var alloc = TempAllocator.Use();
+		return Entity<T>.GetOrThrow(world, new(ecs_import_c(world,
+			new() { Data = new() { Pointer = &MetricsImport } },
+			alloc.AllocateCString("FlecsMetrics"))));
+	}
+
+	[UnmanagedCallersOnly]
+	private static void MetricsImport(ecs_world_t* world)
+		=> FlecsMetricsImport(world);
+}

src/gaemstone/Flecs/Monitor.cs

@@ -3,18 +3,18 @@ using gaemstone.ECS;
 using gaemstone.ECS.Utility;
 using static flecs_hub.flecs;
 
-namespace gaemstone.Flecs.Systems;
+namespace gaemstone.Flecs;
 
 [BuiltIn, Module, Path("/flecs/monitor")]
 public unsafe partial class Monitor
-	: IModuleInitializer
+	: IModuleImport
 {
-	public static void Initialize<T>(Entity<T> module)
+	static Entity<T> IModuleImport.Import<T>(World<T> world)
 	{
 		using var alloc = TempAllocator.Use();
-		ecs_import_c(module.World,
+		return Entity<T>.GetOrThrow(world, new(ecs_import_c(world,
 			new() { Data = new() { Pointer = &MonitorImport } },
-			alloc.AllocateCString("FlecsMonitor"));
+			alloc.AllocateCString("FlecsMonitor"))));
 	}
 
 	[UnmanagedCallersOnly]

src/gaemstone/Flecs/Pipeline.cs

@@ -1,9 +1,14 @@
+using System.Runtime.InteropServices;
 using gaemstone.ECS;
+using gaemstone.ECS.Utility;
+using static flecs_hub.flecs;
 
 namespace gaemstone.Flecs;
 
 [BuiltIn, Module, Path("/flecs/pipeline")]
-public partial class Pipeline
+[DependsOn<gaemstone.Flecs.System>]
+public unsafe partial class Pipeline
+	: IModuleImport
 {
 	[Entity] public struct Phase {  }
 
@@ -90,4 +95,17 @@ public partial class Pipeline
 	[Entity, Add<Phase>]
 	[DependsOn<OnStore>]
 	public struct PostFrame {  }
+
+
+	static Entity<T> IModuleImport.Import<T>(World<T> world)
+	{
+		using var alloc = TempAllocator.Use();
+		return Entity<T>.GetOrThrow(world, new(ecs_import_c(world,
+			new() { Data = new() { Pointer = &PipelineImport } },
+			alloc.AllocateCString("FlecsPipeline"))));
+	}
+
+	[UnmanagedCallersOnly]
+	private static void PipelineImport(ecs_world_t* world)
+		=> FlecsPipelineImport(world);
 }

src/gaemstone/Flecs/Rest.cs

@@ -3,22 +3,26 @@ using gaemstone.ECS;
 using gaemstone.ECS.Utility;
 using static flecs_hub.flecs;
 
-namespace gaemstone.Flecs.Systems;
+namespace gaemstone.Flecs;
 
 [BuiltIn, Module, Path("/flecs/rest")]
+[DependsOn<gaemstone.Flecs.Pipeline>]
 public unsafe partial class Rest
-	: IModuleInitializer
+	: IModuleImport
 {
-	public static void Initialize<T>(Entity<T> module)
+	static Entity<T> IModuleImport.Import<T>(World<T> world)
 	{
-		using (var alloc = TempAllocator.Use())
+		using var alloc = TempAllocator.Use();
-			ecs_import_c(module.World,
+
-				new() { Data = new() { Pointer = &RestImport } },
+		var module = Entity<T>.GetOrThrow(world, new(ecs_import_c(world,
-				alloc.AllocateCString("FlecsRest"));
+			new() { Data = new() { Pointer = &RestImport } },
+			alloc.AllocateCString("FlecsRest"))));
 
 		module.NewChild("Rest").Build()
 			.CreateLookup<EcsRest>()
 			.Set(new EcsRest { port = 27750 });
+
+		return module;
 	}
 
 	[UnmanagedCallersOnly]

src/gaemstone/Flecs/Script.cs

@@ -0,0 +1,24 @@
+using System.Runtime.InteropServices;
+using gaemstone.ECS;
+using gaemstone.ECS.Utility;
+using static flecs_hub.flecs;
+
+namespace gaemstone.Flecs;
+
+[BuiltIn, Module, Path("/flecs/script")]
+[DependsOn<gaemstone.Flecs.Meta>]
+public unsafe partial class Script
+	: IModuleImport
+{
+	static Entity<T> IModuleImport.Import<T>(World<T> world)
+	{
+		using var alloc = TempAllocator.Use();
+		return Entity<T>.GetOrThrow(world, new(ecs_import_c(world,
+			new() { Data = new() { Pointer = &ScriptImport } },
+			alloc.AllocateCString("FlecsScript"))));
+	}
+
+	[UnmanagedCallersOnly]
+	private static void ScriptImport(ecs_world_t* world)
+		=> FlecsScriptImport(world);
+}

src/gaemstone/Flecs/System.cs

@@ -0,0 +1,23 @@
+using System.Runtime.InteropServices;
+using gaemstone.ECS;
+using gaemstone.ECS.Utility;
+using static flecs_hub.flecs;
+
+namespace gaemstone.Flecs;
+
+[BuiltIn, Module, Path("/flecs/system")]
+public unsafe partial class System
+	: IModuleImport
+{
+	static Entity<T> IModuleImport.Import<T>(World<T> world)
+	{
+		using var alloc = TempAllocator.Use();
+		return Entity<T>.GetOrThrow(world, new(ecs_import_c(world,
+			new() { Data = new() { Pointer = &SystemImport } },
+			alloc.AllocateCString("FlecsSystem"))));
+	}
+
+	[UnmanagedCallersOnly]
+	private static void SystemImport(ecs_world_t* world)
+		=> FlecsSystemImport(world);
+}

src/gaemstone/Flecs/Timer.cs

@@ -0,0 +1,24 @@
+using System.Runtime.InteropServices;
+using gaemstone.ECS;
+using gaemstone.ECS.Utility;
+using static flecs_hub.flecs;
+
+namespace gaemstone.Flecs;
+
+[BuiltIn, Module, Path("/flecs/timer")]
+[DependsOn<gaemstone.Flecs.Pipeline>]
+public unsafe partial class Timer
+	: IModuleImport
+{
+	static Entity<T> IModuleImport.Import<T>(World<T> world)
+	{
+		using var alloc = TempAllocator.Use();
+		return Entity<T>.GetOrThrow(world, new(ecs_import_c(world,
+			new() { Data = new() { Pointer = &TimerImport } },
+			alloc.AllocateCString("FlecsTimer"))));
+	}
+
+	[UnmanagedCallersOnly]
+	private static void TimerImport(ecs_world_t* world)
+		=> FlecsTimerImport(world);
+}

src/gaemstone/Flecs/Units.cs

@@ -0,0 +1,23 @@
+using System.Runtime.InteropServices;
+using gaemstone.ECS;
+using gaemstone.ECS.Utility;
+using static flecs_hub.flecs;
+
+namespace gaemstone.Flecs;
+
+[BuiltIn, Module, Path("/flecs/units")]
+public unsafe partial class Units
+	: IModuleImport
+{
+	static Entity<T> IModuleImport.Import<T>(World<T> world)
+	{
+		using var alloc = TempAllocator.Use();
+		return Entity<T>.GetOrThrow(world, new(ecs_import_c(world,
+			new() { Data = new() { Pointer = &UnitsImport } },
+			alloc.AllocateCString("FlecsUnits"))));
+	}
+
+	[UnmanagedCallersOnly]
+	private static void UnitsImport(ecs_world_t* world)
+		=> FlecsUnitsImport(world);
+}

src/gaemstone/Universe+Modules.cs

@@ -1,8 +1,4 @@
 using System;
-using System.Collections;
-using System.Collections.Generic;
-using System.Collections.Immutable;
-using System.Linq;
 using gaemstone.ECS;
 using static gaemstone.Flecs.Core;
 using Module = gaemstone.Flecs.Core.Module;
@@ -10,126 +6,100 @@ using Module = gaemstone.Flecs.Core.Module;
 namespace gaemstone;
 
 public class ModuleManager<TContext>
-	: IEnumerable<ModuleManager<TContext>.IModuleInfo>
 {
-	private readonly Dictionary<Entity<TContext>, IModuleInfo> _modules = new();
-
 	public Universe<TContext> Universe { get; }
-	public ModuleManager(Universe<TContext> universe)
+	public World<TContext> World => Universe.World;
-		=> Universe = universe;
 
-	internal IModuleInfo? Lookup(Entity<TContext> entity)
+	private readonly Rule<TContext> _findDisabledDeps;
-		=> _modules.GetValueOrDefault(entity);
+	private readonly Rule<TContext> _findDependents;
 
-	public Entity<TContext> Register<T>()
+	private readonly ECS.Variable _findDisabledDepsThisVar;
-		where T : IModule
+	private readonly ECS.Variable _findDependentsModuleVar;
+
+	public ModuleManager(Universe<TContext> universe)
 	{
-		// if (!typeof(T).IsAssignableTo(typeof(IModule))) throw new ArgumentException(
+		Universe = universe;
-		// 	$"The specified type {typeof(T)} does not implement IModule", nameof(T));
 
-		var module = new ModuleInfo<T>(Universe);
+		World.New("/gaemstone/ModuleInfo").Symbol("ModuleInfo")
-		_modules.Add(module.Entity, module);
+			.Build().InitComponent<IModuleInfo>();
-		TryEnableModule(module);
+
-		return module.Entity;
+		_findDisabledDeps = new(World, new("(DependsOn, $dep), Disabled($dep)"));
+		_findDependents   = new(World, new("ModuleInfo, Disabled, (DependsOn, $module)"));
+
+		_findDisabledDepsThisVar = _findDisabledDeps.ThisVar
+			?? throw new InvalidOperationException($"Could not find $this of {nameof(_findDisabledDeps)}");
+		_findDependentsModuleVar = _findDependents.Variables["module"]
+			?? throw new InvalidOperationException($"Could not find $module of {nameof(_findDependents)}");
 	}
 
-	private void TryEnableModule(IModuleInfo module)
+	public Entity<TContext> Import<T>()
+		where T : IModule, IModuleImport
 	{
-		if (!module.Dependencies.All(dep => dep.IsDependencyMet)) return;
+		foreach (var dep in T.Dependencies)
+			if (World.LookupPathOrNull(dep) == null) throw new InvalidOperationException(
+				$"Missing required dependency {dep} for built-in module {T.Path}");
 
-		Console.WriteLine($"Enabling module {module.Entity.Path}");
+		Console.WriteLine($"Importing built-in module {T.Path}");
 
-		module.Enable();
+		var entity = T.Import(World);
+		entity.Set<IModuleInfo>(new ModuleInfo<T>());
+		T.OnEnable(entity);
+		return entity;
+	}
 
-		// Find other modules that might be missing this module as a dependency.
+	public Entity<TContext> Register<T>()
-		foreach (var other in _modules.Values) {
+		where T : IModule
-			if (other.IsInitialized) continue;
+	{
-			var dependency = other.Dependencies.FirstOrDefault(dep => dep.Entity == module.Entity);
+		if (T.IsBuiltIn) throw new ArgumentException(
-			if (dependency == null) continue;
+			$"Unexpected operation, {T.Path} is a built-in module");
 
-			dependency.Info = module;
+		var builder = World.New(T.Path)
-			dependency.IsDependencyMet = true;
+			.Add<Module>().Add<Disabled>()
+			.Set<IModuleInfo>(new ModuleInfo<T>());
 
-			TryEnableModule(other);
+		foreach (var depPath in T.Dependencies) {
+			var dependency = World.LookupPathOrNull(depPath) ??
+				World.New(depPath).Add<Module>().Add<Disabled>().Build();
+			builder.Add<DependsOn>(dependency);
 		}
+
+		var module = builder.Build().CreateLookup<T>();
+
+		// Ensure all parent entities have the Module tag set.
+		for (var p = module.Parent; p is Entity<TContext> parent; p = parent.Parent)
+			parent.Add<Module>();
+
+		Console.WriteLine($"Registered module {module.Path}");
+
+		TryEnableModule(module);
+		return module;
 	}
 
-	public interface IModuleInfo
+	private void TryEnableModule(Entity<TContext> module)
 	{
-		Entity<TContext> Entity { get; }
+		// Skip if module is already enabled.
-		IReadOnlyCollection<ModuleDependency> Dependencies { get; }
+		if (module.IsEnabled) return;
-		bool IsInitialized { get; }
+		// Skip if module has any not-yet-enabled dependencies.
-		void Enable();
+		if (_findDisabledDeps.Iter().SetVar(_findDisabledDepsThisVar, module).Any()) return;
-	}
 
-	// IEnumerable implementation
+		Console.WriteLine($"Enabling module {module.Path}");
-	public IEnumerator<IModuleInfo> GetEnumerator() => _modules.Values.GetEnumerator();
+		module.GetOrThrow<IModuleInfo>().OnEnable(module);
-	IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
+		module.Enable();
 
+		// Get all modules that depend on this one and try to enabled them if they now have their dependencies met.
+		foreach (var dependent in _findDependents.Iter().SetVar(_findDependentsModuleVar, module).GetAllEntities())
+			TryEnableModule(dependent);
+	}
 
-	public class ModuleDependency
+	public interface IModuleInfo
 	{
-		public Entity<TContext> Entity { get; }
+		void OnEnable(Entity<TContext> entity);
-		public IModuleInfo? Info { get; internal set; }
-		public bool IsDependencyMet { get; internal set; }
-
-		public ModuleDependency(Entity<TContext> entity,
-			IModuleInfo? info = null, bool isDependencyMet = false)
-		{
-			Entity = entity;
-			Info = info;
-			IsDependencyMet = isDependencyMet;
-		}
 	}
 
 	internal class ModuleInfo<T> : IModuleInfo
 		 where T : IModule
 	{
-		public Entity<TContext> Entity { get; }
+		public void OnEnable(Entity<TContext> entity)
-		public IReadOnlyCollection<ModuleDependency> Dependencies { get; }
+			=> T.OnEnable(entity);
-		public bool IsInitialized { get; private set; }
-
-		public ModuleInfo(Universe<TContext> universe)
-		{
-			var world = universe.World;
-
-			if (T.IsBuiltIn)
-			{
-				Entity = world.LookupPathOrThrow(T.Path);
-				Dependencies = Array.Empty<ModuleDependency>();
-			}
-			else
-			{
-				var builder = world.New(T.Path);
-				var deps    = new List<ModuleDependency>();
-
-				builder.Add<Module>();
-				foreach (var dependsPath in T.Dependencies) {
-					var dependency = world.LookupPathOrNull(dependsPath) ??
-						world.New(dependsPath).Add<Module>().Add<Disabled>().Build();
-
-					var depModule = universe.Modules.Lookup(dependency);
-					var isDepInit = (depModule?.IsInitialized == true);
-
-					deps.Add(new(dependency, depModule, isDepInit));
-					if (!isDepInit) builder.Add<Disabled>();
-					builder.Add<DependsOn>(dependency);
-				}
-
-				Entity = builder.Build().CreateLookup<T>();
-				Dependencies = deps.AsReadOnly();
-
-				// Ensure all parent entities have the Module tag set.
-				for (var p = Entity.Parent; p is Entity<TContext> parent; p = parent.Parent)
-					parent.Add<Module>();
-			}
-		}
-
-		public void Enable()
-		{
-			Entity.Enable();
-			T.Initialize(Entity);
-			IsInitialized = true;
-		}
 	}
 }

src/gaemstone/Universe.cs

@@ -9,17 +9,22 @@ public class Universe<TContext>
 
 	public Universe()
 	{
-		World   = new();
+		World   = new(minimal: true);
 		Modules = new(this);
 
 		// Bootstrap [Relation] tag, since it will be added to some Flecs types.
 		World.New("/gaemstone/Doc/Relation").Build()
 			.CreateLookup<Doc.Relation>();
 
-		// Bootstrap built-in (static) modules from Flecs.
+		// Bootstrap core module from Flecs.
-		Modules.Register<Flecs.Core>();
+		Modules.Import<Flecs.Core>();
-		Modules.Register<Flecs.Doc>();
+
-		Modules.Register<Flecs.Pipeline>();
+		// Import addon modules from Flecs we use for the engine.
+		Modules.Import<Flecs.System>();
+		Modules.Import<Flecs.Pipeline>();
+		Modules.Import<Flecs.Meta>();
+		Modules.Import<Flecs.Doc>();
+		Modules.Import<Flecs.CoreDoc>();
 
 		Modules.Register<Doc>();
 	}