Make the output type of a property source read-only.

Assets/Cryville/Crtr/Judge.cs

@@ -252,7 +252,8 @@ namespace Cryville.Crtr {
 			readonly Func<string> _cb;
 			readonly ArrayPool<byte> _pool;
 			byte[] _buf;
-			public ScoreStringSrc(ArrayPool<byte> pool, Func<string> cb) {
+			public ScoreStringSrc(ArrayPool<byte> pool, Func<string> cb)
+				: base(PdtInternalType.String) {
 				_pool = pool;
 				_cb = cb;
 			}
@@ -263,7 +264,7 @@ namespace Cryville.Crtr {
 					_buf = null;
 				}
 			}
-			protected override unsafe int InternalGet() {
+			protected override unsafe void InternalGet() {
 				var src = _cb();
 				int strlen = src.Length;
 				buf = _pool.Rent(sizeof(int) + strlen * sizeof(char));
@@ -273,7 +274,6 @@ namespace Cryville.Crtr {
 					int i = 0;
 					foreach (var c in src) ptr[i++] = c;
 				}
-				return PdtInternalType.String;
 			}
 		}
 		#endregion