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TaskContinuationOptions Enumeration

Specifies the behavior for a task that is created by using the Task::ContinueWith or Task<TResult>::ContinueWith method.

This enumeration has a FlagsAttribute attribute that allows a bitwise combination of its member values.

Namespace:  System.Threading.Tasks
Assemblies:   System.Threading.Tasks (in System.Threading.Tasks.dll)
  mscorlib (in mscorlib.dll)

[FlagsAttribute]
public enum class TaskContinuationOptions

Member nameDescription
Supported by Portable Class LibraryAttachedToParentSpecifies that the continuation, if it is a child task, is attached to a parent in the task hierarchy. The continuation can be a child task only if its antecedent is also a child task. By default, a child task (that is, an inner task created by an outer task) executes independently of its parent. You can use the TaskContinuationOptions::AttachedToParent option so that the parent and child tasks are synchronized. Note that if a parent task is configured with the DenyChildAttach option, the AttachedToParent option in the child task has no effect, and the child task will execute as a detached child task. For more information, see Attached and Detached Child Tasks.
DenyChildAttachSpecifies that any child task (that is, any nested inner task created by this continuation) that is created with the TaskCreationOptions::AttachedToParent option and attempts to execute as an attached child task will not be able to attach to the parent task and will execute instead as a detached child task. For more information, see Attached and Detached Child Tasks.
Supported by Portable Class LibraryExecuteSynchronouslySpecifies that the continuation task should be executed synchronously. With this option specified, the continuation runs on the same thread that causes the antecedent task to transition into its final state. If the antecedent is already complete when the continuation is created, the continuation will run on the thread that creates the continuation. If the antecedent's CancellationTokenSource is disposed in a finally block (Finally in Visual Basic), a continuation with this option will run in that finally block. Only very short-running continuations should be executed synchronously. Because the task executes synchronously, there is no need to call a method such as Task::Wait to ensure that the calling thread waits for the task to complete.
HideSchedulerSpecifies that tasks created by the continuation by calling methods such as Task::Run or Task::ContinueWith see the default scheduler (TaskScheduler::Default) rather than the scheduler on which this continuation is running to be the current scheduler.
LazyCancellationIn the case of continuation cancellation, prevents completion of the continuation until the antecedent has completed.
Supported by Portable Class LibraryLongRunningSpecifies that a continuation will be a long-running, course-grained operation. It provides a hint to the TaskScheduler that oversubscription may be warranted.
Supported by Portable Class LibraryNoneWhen no continuation options are specified, specifies that default behavior should be used when executing a continuation. The continuation runs asynchronously when the antecedent task completes, regardless of the antecedent's final Task::Status property value. It the continuation is a child task, it is created as a detached nested task.
Supported by Portable Class LibraryNotOnCanceledSpecifies that the continuation task should not be scheduled if its antecedent was canceled. An antecedent is canceled if its Task::Status property upon completion is TaskStatus::Canceled. This option is not valid for multi-task continuations.
Supported by Portable Class LibraryNotOnFaultedSpecifies that the continuation task should not be scheduled if its antecedent threw an unhandled exception. An antecedent throws an unhandled exception if its Task::Status property upon completion is TaskStatus::Faulted. This option is not valid for multi-task continuations.
Supported by Portable Class LibraryNotOnRanToCompletionSpecifies that the continuation task should not be scheduled if its antecedent ran to completion. An antecedent runs to completion if its Task::Status property upon completion is TaskStatus::RanToCompletion. This option is not valid for multi-task continuations.
Supported by Portable Class LibraryOnlyOnCanceledSpecifies that the continuation should be scheduled only if its antecedent was canceled. An antecedent is canceled if its Task::Status property upon completion is TaskStatus::Canceled. This option is not valid for multi-task continuations.
Supported by Portable Class LibraryOnlyOnFaultedSpecifies that the continuation task should be scheduled only if its antecedent threw an unhandled exception. An antecedent throws an unhandled exception if its Task::Status property upon completion is TaskStatus::Faulted. The OnlyOnFaulted option guarantees that the Task::Exception property in the antecedent is not nullptr. You can use that property to catch the exception and see which exception caused the task to fault. If you do not access the Exception property, the exception is unhandled. Also, if you attempt to access the Result property of a task that has been canceled or has faulted, a new exception is thrown. This option is not valid for multi-task continuations.
Supported by Portable Class LibraryOnlyOnRanToCompletionSpecifies that the continuation should be scheduled only if its antecedent ran to completion. An antecedent runs to completion if its Task::Status property upon completion is TaskStatus::RanToCompletion. This option is not valid for multi-task continuations.
Supported by Portable Class LibraryPreferFairnessA hint to a TaskScheduler to schedule task in the order in which they were scheduled, so that tasks scheduled sooner are more likely to run sooner, and tasks scheduled later are more likely to run later.
RunContinuationsAsynchronouslySpecifies that the continuation task should be run asynchronously. This option has precedence over TaskContinuationOptions::ExecuteSynchronously.

.NET Framework

Supported in: 4.6, 4.5, 4

.NET Framework Client Profile

Supported in: 4

Portable Class Library

Supported in: Portable Class Library

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8
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