How can I start a continuation task instance?

Question

I have this method that Starts a Task and returns the last cahined Task to get the result:

public Task<double> GetTask()
{
    return Task.Factory.StartNew((() => 10))
        .ContinueWith(i =>
        {
            return i.Result + 2;
        })
        .ContinueWith(i =>
        {
            return (double)i.Result;
        });
}

I would like to have the same method returning the same task but without starting it automatically with the Task.Factory.StartNew like this:

public Task<double> GetTask2()
{
    return new Task<int>((() => 10))
        .ContinueWith(i =>
        {
            return i.Result + 2;
        })
        .ContinueWith(i =>
        {
            return (double)i.Result;
        });
}

Anyway I wasn't able to find a way to start the task returned by GetTask2 and get the result. How can I start it and get the result?

Answer 1

Something like this:

public Task<double> GetTask()
{
    var rootTask = new Task<int>((() => 10));
    var continuationTask = rootTask
        .ContinueWith(i =>
        {
            return i.Result + 2;
        })
        .ContinueWith(i =>
        {
            return (double)i.Result;
        });
    rootTask.Start(),
    return continuationTask;
}

If you want to start the task only later, you can return both from your function.