Add some info and prev. value for setters

GamecraftModdingAPI/Block.cs

@@ -137,6 +137,16 @@ namespace GamecraftModdingAPI
 				{typeof(Timer), new[] {CommonExclusiveGroups.BUILD_TIMER_BLOCK_GROUP}}
 			};
 
+		/// <summary>
+		/// Constructs a new instance of T with the given ID and group using dynamically created delegates.
+		/// It's equivalent to new T(EGID) with a minimal overhead thanks to caching the created delegates.
+		/// </summary>
+		/// <param name="id">The block ID</param>
+		/// <param name="group">The block group</param>
+		/// <typeparam name="T">The block's type or Block itself</typeparam>
+		/// <returns>An instance of the provided type</returns>
+		/// <exception cref="BlockTypeException">The block group doesn't match or cannot be found</exception>
+		/// <exception cref="MissingMethodException">The block class doesn't have the needed constructor</exception>
 		private static T New<T>(uint id, ExclusiveGroupStruct? group = null) where T : Block
 		{
 			var type = typeof(T);
@@ -175,8 +185,8 @@ namespace GamecraftModdingAPI
 			il.DeclareLocal(type);
 			il.Emit(OpCodes.Ldarg_0); //Load EGID and pass to constructor
 			il.Emit(OpCodes.Newobj, ctor); //Call constructor
-			il.Emit(OpCodes.Stloc_0);
-			il.Emit(OpCodes.Ldloc_0);
+			//il.Emit(OpCodes.Stloc_0); - doesn't seem like we need these
+			//il.Emit(OpCodes.Ldloc_0);
 			il.Emit(OpCodes.Ret);
 
 			func = (Func<EGID, T>) dynamic.CreateDelegate(typeof(Func<EGID, T>));
@@ -188,6 +198,9 @@ namespace GamecraftModdingAPI
 		public Block(EGID id)
 		{
 			Id = id;
+			if (typeToGroup.TryGetValue(GetType(), out var groups) && groups.All(gr => gr != id.groupID))
+				throw new BlockTypeException("The block has the wrong group! The type is " + GetType() +
+				                             " while the group is " + id.groupID);
 		}
 
 		/// <summary>
@@ -328,6 +341,7 @@ namespace GamecraftModdingAPI
 
 		/// <summary>
 		/// Whether the block exists. The other properties will return a default value if the block doesn't exist.
+		/// If the block was just placed, then this will also return false but the properties will work correctly.
 		/// </summary>
 		public bool Exists => BlockEngine.BlockExists(Id);
 

GamecraftModdingAPI/Blocks/BlockEngine.cs

@@ -85,10 +85,11 @@ namespace GamecraftModdingAPI.Blocks
 		{
 			if (entitiesDB.Exists<T>(block.Id))
 				setter(ref entitiesDB.QueryEntity<T>(block.Id), value);
-			if (block.InitData.Group != null)
+			else if (block.InitData.Group != null)
 			{
 				var initializer = new EntityComponentInitializer(block.Id, block.InitData.Group);
-				ref T structRef = ref (new T[1])[0]; //A reference for a default value for struct
+				T component = initializer.Has<T>() ? initializer.Get<T>() : default;
+				ref T structRef = ref component;
 				setter(ref structRef, value);
 				initializer.Init(structRef);
 			}

GamecraftModdingAPI/Blocks/BlockEngineInit.cs

@@ -9,6 +9,9 @@ namespace GamecraftModdingAPI.Blocks
 {
     public partial class BlockEngine
     {
+        /// <summary>
+        /// Holds information needed to construct a component initializer
+        /// </summary>
         internal struct BlockInitData
         {
             public FasterDictionary<RefWrapper<Type>, ITypeSafeDictionary> Group;
@@ -17,6 +20,9 @@ namespace GamecraftModdingAPI.Blocks
         internal delegate FasterDictionary<RefWrapper<Type>, ITypeSafeDictionary> GetInitGroup(
             EntityComponentInitializer initializer);
 
+        /// <summary>
+        /// Accesses the group field of the initializer
+        /// </summary>
         internal GetInitGroup InitGroup = CreateAccessor<GetInitGroup>("_group");
 
         //https://stackoverflow.com/questions/55878525/unit-testing-ref-structs-with-private-fields-via-reflection