Continuation tasks in .NET TPL: continuation with different result type

Tasks in .NET TPL make it easy to assign tasks that should run upon the completion of a certain task.

We’ll need a basic object with a single property:

public class Series
{
	public int CurrentValue
	{
		get;
		set;
	}
}

Declare a task that increases the CurrentValue in a loop and return the Series. This task is called the antecedent task.

Task<Series> motherTask = Task.Factory.StartNew<Series>(() =>
{
	Series series = new Series();
	for (int i = 0; i < 10000; i++)
	{
		series.CurrentValue++;
	}
	return series;
});

Declare the continuation task where we also use the antecedent as method parameter. Note that the return type of the continuation task can be different from that of the antecedent:

Task continuationTask = motherTask.ContinueWith((Task previousTask) =>
{
	Console.WriteLine("Interim value: {0}", previousTask.Result.CurrentValue);
	return previousTask.Result.CurrentValue * 2;
});

Read the result of the continuation task:

Console.WriteLine("Final value: {0}", continuationTask.Result);

View the list of posts on the Task Parallel Library here.