If my interface must return Task what is the best way to have a no-operation implementation?

Question

In the code below, due to the interface, the class LazyBar must return a task from its method (and for argument\'s sake can\'t be changed). If LazyBar

Answer 1

To add to Reed Copsey's answer about using Task.FromResult, you can improve performance even more if you cache the already completed task since all instances of completed tasks are the same:

public static class TaskExtensions
{
    public static readonly Task CompletedTask = Task.FromResult(false);
}

With TaskExtensions.CompletedTask you can use the same instance throughout the entire app domain.

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The latest version of the .Net Framework (v4.6) adds just that with the Task.CompletedTask static property

Task completedTask = Task.CompletedTask;