Update Operation System

Assets/YooAsset/Runtime/AssetSystem/Operations/InstantiateOperation.cs

@@ -81,7 +81,11 @@ namespace YooAsset
 				Status = EOperationStatus.Succeed;
 			}
 		}
-		public override void Cancel()
+
+		/// <summary>
+		/// 取消实例化对象操作
+		/// </summary>
+		public void Cancel()
 		{
 			if (IsDone == false)
 			{

Assets/YooAsset/Runtime/OperationSystem/AsyncOperationBase.cs

@@ -81,14 +81,6 @@ namespace YooAsset
 				_taskCompletionSource.TrySetResult(null);
 		}
 
-		/// <summary>
-		/// 取消异步操作
-		/// </summary>
-		public virtual void Cancel()
-		{
-			throw new NotImplementedException("Can not cancel operation !");
-		}
-
 		#region 异步编程相关
 		bool IEnumerator.MoveNext()
 		{

Assets/YooAsset/Runtime/OperationSystem/GameAsyncOperation.cs

@@ -1,7 +1,7 @@
 
 namespace YooAsset
 {
-	public class GameAsyncOperation : AsyncOperationBase
+	public abstract class GameAsyncOperation : AsyncOperationBase
 	{
 		internal override void Start()
 		{
@@ -12,7 +12,7 @@ namespace YooAsset
 			OnUpdate();
 		}
 
-		protected virtual void OnStart() { }
+		protected abstract void OnStart();
-		protected virtual void OnUpdate() { }
+		protected abstract void OnUpdate();
 	}
 }