Composing Tasks Together

Tasks can be grouped in interesting ways to describe more complex behavior. By having tasks happen in a certain order and sometimes simultaneously, you can build a complex task out of simpler, reusable tasks. To do this, you can use SequentialTask, ConcurrentTask, and ConditionalTask-based tasks.

SequentialTask.Sequence()

SequentialTask starts and completes each task in the order they are listed.

SequentialTask.Sequence(
  new WaitTask(3.0),
  new DriveForwardTask(3.5));

The example above is a sequence of two tasks: first wait 3 seconds, then drive 3.5 inches forward.

ConcurrentTask.AnyTasks()

ConcurrentTask.AnyTasks starts all tasks at the same time and completes when any one of them has completed.

ConcurrentTask.AnyTasks(
  new WaitTask(3.0),
  new DriveForwardTask(3.5));

The example above runs two tasks at the same time, completing when either 3 seconds have elapsed OR the robot has driven 3.5 inches forward.

ConcurrentTask.AllTasks()

ConcurrentTask.AllTasks starts all tasks at the same time and completes when all of them have completed.

ConcurrentTask.AllTasks(
  new WaitTask(3.0),
  new DriveForwardTask(3.5));

The example above runs two tasks at the same time, completing when 3 seconds have elapsed AND the robot has driven 3.5 inches forward.

ConditionalTask-based tasks

Conditional tasks can use branching logic based on conditions within our tasks. These are implemented as classes inheriting from ConditionalTask, which evaluate a condition (e.g., “elevator is above level 3”) and, based on that, decide which action to perform next. This allows you to create a decision tree based on different conditions so the macro or autonomous routine can respond to the current state of the robot or even the world around it.