Documentation Set for Swarm 2.2
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# ActivityControl

## Name

ActivityControl -- A class that provides an object interface to an activity.

## Description

The ActivityControl class specifies an object that can be attached to an activity (regardless of how or where that activity is created) for the purpose of explicitly controlling the execution of actions on that activity's action plan. There is nothing that available through this class that is not already available through the variables or messages available via the activity itself. However, it packages up the main control messages and makes them available to other objects that may need control over an activity, thereby shielding the activity from directly receiving messages from outside objects and saving the user from having to parse the more complex interface to the activity.

## Protocols adopted by ActivityControl

SwarmObject CREATABLE

## Methods

### Phase: Using

- - (id <ScheduleActivity>)getActivity
  Return the controlled activity.

- - (void)terminate
  Recursively removes all subactivities.

- - (id <Symbol>)getStatus
  The getStatus method returns the status of the activity.

- - (void)updateStateVar
  The updateStateVar method updates the ActivityControl instance variables and tests for the continued existence of the activity that is being controlled. This message is sent on each cycle of the schedule for the activity being controlled.

- - (id <Symbol>)stepUntil: (timeval_t)stopTime
  The stepUntil: method sends a stepUntil: message to the activity if conditions are appropriate. This causes all actions on the activity's schedule, including any actions on subactivities' schedules, to be executed until the activity's relative time is equal to stopTime - 1.

- - (id <Symbol>)stepAction
  The step method sends a step message to the activity if the conditions are appropriate. It causes the execution of a single action.

- - (id <Symbol>)nextAction
  The next method sends a next message to the activity if the conditions are appropriate. It runs an activity forward through as many actions as necessary until it hits a breakFunction, at which point it walks back up the tree of activities and returns Stopped. In most cases, this means that an entire action or action group on the activity under control will be executed, including completion of all subactivities.

- - (id <Symbol>)stopActivity
  The stop method sends a stop message to the activity if the conditions are appropriate. This message causes the control to move back up the run-stack and resume at the place in the code where the run was first executed. The next action on the super-activity will begin without finishing the rest of the current activity's actions.

- - (id <Symbol>)runActivity
  The run method sends a run message to the activity if the conditions are appropriate. This message causes the activity to continue executing the actions on its schedule until either no other actions are waiting, or until the execution of actions is stopped by a subactivity or stopped by a stop message to the activity. If the activity completes executing all the actions on its schedule, the run method returns Completed.

- - (void)attachToActivity: (id <ScheduleActivity>)anActivity
  The attachToActivity: method sets an instance variable inside the ActivityControl object that points to the Activity to be controlled. It then creates a Schedule upon which it places a message to itself to update its own variables.

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