Many minor changes

- Remove World.DependsOn - no longer needed
- Remove Id.AsEntity and .AsPair
- Don't display hex values in .ToString()
- Fix Id.ToString printing "Identifier", not "Id"
- Add a couple of TODO comments
- Rearrange some lines

src/gaemstone.ECS/Component.cs

@@ -49,10 +49,8 @@ public unsafe readonly struct ReferenceHandle
 
 	private readonly nint _value;
 
-	public object? Target =>
+	public object? Target => (_value != default)
-		(_value != default)
+		? ((GCHandle)_value).Target : null;
-			? ((GCHandle)_value).Target
-			: null;
 
 	private ReferenceHandle(nint value)
 		=> _value = value;

src/gaemstone.ECS/Entity.cs

@@ -20,7 +20,7 @@ public readonly struct Entity
 	public override bool Equals(object? obj) => (obj is Entity other) && Equals(other);
 	public override int GetHashCode() => Value.Data.GetHashCode();
 	public override string? ToString()
-		=> IsSome ? $"Entity(0x{Value.Data.Data:X})"
+		=> IsSome ? $"Entity({Value.Data.Data})"
 		          :  "Entity.None";
 
 	public static bool operator ==(Entity left, Entity right) =>  left.Equals(right);

src/gaemstone.ECS/EntityBase.cs

@@ -1,5 +1,6 @@
 namespace gaemstone.ECS;
 
+// TODO: Turn this into an interface?
 public abstract class EntityBase<TReturn>
 {
 	public abstract World World { get; }

src/gaemstone.ECS/EntityBuilder.cs

@@ -38,6 +38,7 @@ public class EntityBuilder
 
 	/// <summary> Ids to add to the new or existing entity. </summary>
 	private readonly HashSet<Id> _toAdd = new();
+	// (ChildOf, *) is handled explicitly, it won't be added to _toAdd.
 	private Entity _parent = Entity.None;
 
 	/// <summary> String expression with components to add. </summary>
@@ -52,7 +53,7 @@ public class EntityBuilder
 	public override EntityBuilder Add(Id id)
 	{
 		// If adding a ChildOf relation, store the parent separately.
-		if (id.AsPair(World) is (EntityRef relation, EntityRef target) &&
+		if (new IdRef(World, id).AsPair() is (EntityRef relation, EntityRef target) &&
 			(relation == World.ChildOf)) { _parent = target; return this; }
 
 		if (_toAdd.Count == 31) throw new NotSupportedException(

src/gaemstone.ECS/EntityRef.cs

@@ -58,13 +58,15 @@ public unsafe class EntityRef
 	private static EntityPath? EnsureRelativePath(EntityPath? path)
 	{
 		if (path?.IsAbsolute == true) throw new ArgumentException(
-			$"Path '{path}' must not be absolute", nameof(path)); return path;
+			$"Path '{path}' must not be absolute", nameof(path));
+		return path;
 	}
 
 
 	public EntityRef? Parent
 		=> GetTargets(World.ChildOf).FirstOrDefault();
 
+	// TODO: Change to property after all?
 	public IEnumerable<EntityRef> GetChildren()
 	{
 		foreach (var iter in Iterator.FromTerm(World, new(World.ChildOf, this)))

src/gaemstone.ECS/Id.cs

@@ -7,12 +7,11 @@ public readonly struct Id
 	: IEquatable<Id>
 {
 	public readonly ecs_id_t Value;
+	public IdFlags Flags => (IdFlags)(Value & ECS_ID_FLAGS_MASK);
 
 	public bool IsPair     => ecs_id_is_pair(this);
 	public bool IsWildcard => ecs_id_is_wildcard(this);
 
-	public IdFlags Flags => (IdFlags)(Value & ECS_ID_FLAGS_MASK);
-
 	public Entity RelationUnsafe => new(new() { Data = (Value & ECS_COMPONENT_MASK) >> 32 });
 	public Entity TargetUnsafe   => new(new() { Data =  Value & ECS_ENTITY_MASK });
 
@@ -26,17 +25,12 @@ public readonly struct Id
 			((relation.Value.Data << 32) & ECS_COMPONENT_MASK) |
 			(   target.Value.Data        & ECS_ENTITY_MASK   )));
 
-	public EntityRef? AsEntity(World world)
-		=> new IdRef(world, this).AsEntity();
-	public (EntityRef Relation, EntityRef Target)? AsPair(World world)
-		=> new IdRef(world, this).AsPair();
-
 	public bool Equals(Id other) => Value.Data == other.Value.Data;
 	public override bool Equals(object? obj) => (obj is Id other) && Equals(other);
 	public override int GetHashCode() => Value.Data.GetHashCode();
 	public override string? ToString()
-		=> (Flags != default) ? $"Identifier(0x{Value.Data:X}, Flags={Flags})"
+		=> (Flags != default) ? $"Id({Value.Data}, Flags={Flags})"
-		                      : $"Identifier(0x{Value.Data:X})";
+		                      : $"Id({Value.Data})";
 
 	public static bool operator ==(Id left, Id right) =>  left.Equals(right);
 	public static bool operator !=(Id left, Id right) => !left.Equals(right);

src/gaemstone.ECS/IdRef.cs

@@ -9,12 +9,12 @@ public unsafe class IdRef
 {
 	public World World { get; }
 	public Id Id { get; }
-
 	public IdFlags Flags => Id.Flags;
+
 	public bool IsPair     => Id.IsPair;
 	public bool IsWildcard => Id.IsWildcard;
-	public bool IsValid    => ecs_id_is_valid(World, this);
 
+	public bool IsValid => ecs_id_is_valid(World, this);
 	public bool IsInUse => ecs_id_in_use(World, this);
 	public int  Count   => ecs_count_id(World, this);
 
@@ -26,10 +26,10 @@ public unsafe class IdRef
 
 	public static IdRef Pair(World world, Entity relation, Entity target)
 		=> new(world, Id.Pair(relation, target));
-	public static IdRef Pair(Entity relation, EntityRef target)
-		=> Pair(target.World, relation, target);
 	public static IdRef Pair(EntityRef relation, Entity target)
 		=> Pair(relation.World, relation, target);
+	public static IdRef Pair(Entity relation, EntityRef target)
+		=> Pair(target.World, relation, target);
 	public static IdRef Pair(EntityRef relation, EntityRef target)
 		=> Pair(relation.World, relation, target);
 

src/gaemstone.ECS/World+Lookup.cs

@@ -36,6 +36,7 @@ public unsafe partial class World
 		=> LookupAlive(entity) ?? throw new EntityNotFoundException(
 			$"Entity {entity} is not alive");
 
+	// TODO: Simplify method names?
 	public EntityRef? LookupByPath(EntityPath path)
 		=> LookupByPath(default, path);
 	public EntityRef? LookupByPath(Entity parent, EntityPath path)
@@ -45,6 +46,7 @@ public unsafe partial class World
 	public EntityRef LookupByPathOrThrow(Entity parent, EntityPath path)
 		=> new(this, EntityPath.Lookup(this, parent, path, true));
 
+	// TODO: Provide overload that uses a UTF-8 byte span?
 	public EntityRef? LookupBySymbol(string symbol)
 	{
 		using var alloc = TempAllocator.Use();

src/gaemstone.ECS/World.cs

@@ -11,7 +11,6 @@ public unsafe partial class World
 	// Flecs built-ins that are important to internals.
 	internal EntityRef ChildOf { get; }
 	internal EntityRef Disabled { get; }
-	internal EntityRef DependsOn { get; }
 
 	public bool IsDeferred => ecs_is_deferred(this);
 	public bool IsQuitRequested => ecs_should_quit(this);
@@ -27,7 +26,6 @@ public unsafe partial class World
 
 		ChildOf  = LookupByPathOrThrow("/flecs/core/ChildOf");
 		Disabled = LookupByPathOrThrow("/flecs/core/Disabled");
-		DependsOn = LookupByPathOrThrow("/flecs/core/DependsOn");
 	}
 
 	public void Dispose()