new object creation logic

OpenRA.Game/ObjectCreator.cs

@@ -3,6 +3,7 @@ using System.IO;
 using System.Linq;
 using System.Reflection;
 using OpenRA.FileFormats;
+using System.Collections.Generic;
 
 namespace OpenRA
 {
@@ -30,19 +31,61 @@ namespace OpenRA
 		public static Action<string> MissingTypeAction = 
 			s => { throw new InvalidOperationException("Cannot locate type: {0}".F(s)); };
 
-		public T CreateObject<T>(string classname)
+		public T CreateObject<T>(string className)
 		{
-			foreach (var mod in ModAssemblies)
-			{
-				var fullTypeName = mod.Second + "." + classname;
-				var obj = mod.First.CreateInstance(fullTypeName);
-				if (obj != null)
-					return (T)obj;
-			}
+			return CreateObject<T>( className, new Dictionary<string, object>() );
+		}
 
-			MissingTypeAction(classname);
+		public T CreateObject<T>( string className, Dictionary<string, object> args )
+		{
+			foreach( var mod in ModAssemblies )
+			{
+				var type = mod.First.GetType( mod.Second + "." + className, false );
+				if( type == null ) continue;
+				var ctors = type.GetConstructors().Where( x => x.HasAttribute<UseCtorAttribute>() ).ToList();
+				if( ctors.Count == 0 )
+					return (T)CreateBasic( type );
+				else if( ctors.Count == 1 )
+					return (T)CreateUsingArgs( ctors[ 0 ], args );
+				else
+					throw new InvalidOperationException( "ObjectCreator: UseCtor on multiple constructors; invalid." );
+			}
+			MissingTypeAction(className);
 			return default(T);
 		}
 
+		public object CreateBasic( Type type )
+		{
+			return type.GetConstructor( new Type[ 0 ] ).Invoke( new object[ 0 ] );
+		}
+
+		public object CreateUsingArgs( ConstructorInfo ctor, Dictionary<string, object> args )
+		{
+			var p = ctor.GetParameters();
+			var a = new object[ p.Length ];
+			for( int i = 0 ; i < p.Length ; i++ )
+			{
+				var attrs = p[ i ].GetCustomAttributes<ParamAttribute>();
+				if( attrs.Length != 1 ) throw new InvalidOperationException( "ObjectCreator: argument in [UseCtor] doesn't have [Param]" );
+				a[ i ] = args[ attrs[ 0 ].ParamName ];
+			}
+			return ctor.Invoke( a );
+		}
+
+		[AttributeUsage( AttributeTargets.Parameter )]
+		public class ParamAttribute : Attribute
+		{
+			public string ParamName { get; private set; }
+
+			public ParamAttribute( string paramName )
+			{
+				ParamName = paramName;
+			}
+		}
+
+		[AttributeUsage( AttributeTargets.Constructor )]
+		public class UseCtorAttribute : Attribute
+		{
+		}
 	}
 }