Robot Parameters

The Robot class provides a mechanism to manage parameters associated with a robot. Each parameter has the following attributes:

  • Value: The current value of the parameter.

  • TTL: Time-to-live in seconds (None | int). This attribute is optional. If not set (default is None), the parameter’s Value will persist indefinitely. If set to an integer, the parameter’s Value will automatically reset to None after the specified number of seconds.

Additionally, when a parameter’s Value expires (due to TTL), an expired event is sent to any subscribers monitoring the parameter via the websockets events mechanism.

Important: If the TTL attribute is not set, no expiration will occur, and the parameter’s Value will remain unchanged until explicitly modified.

Usage

Setting a Parameter’s Value

To set the value of an existing parameter or create a new one:

robot = FleetRobot("robot_id")
robot.Parameter["parameter_name"].Value = "new_value"

If the parameter does not exist, it will be created automatically.

Setting a Parameter with TTL

To set a parameter with a TTL (optional):

robot = FleetRobot("robot_id")
robot.Parameter["parameter_name"].TTL = 10  # TTL in seconds
robot.Parameter["parameter_name"].Value = "temporary_value"

In this example, the Value of the parameter will reset to None after 10 seconds, and an expired event will be sent to subscribers.

If the TTL is not set, the parameter’s Value will persist indefinitely.

Example: Creating and Using Parameters

robot = FleetRobot("robot_id")

# Create a parameter without TTL (no expiration)
robot.Parameter["mesh"].Value = "mesh_name"

# Create a parameter with TTL
robot.Parameter["status"].TTL = 5  # Expires after 5 seconds
robot.Parameter["status"].Value = "active"

# Accessing parameter values
print(robot.Parameter["mesh"].Value)  # Output: "mesh_name"
print(robot.Parameter["status"].Value)  # Output: "active"

# After 5 seconds, the status parameter will expire
# and its value will reset to None.

Subscribing to Parameter Events

The expired event is sent to subscribers when a parameter’s Value expires. To monitor these events, use the websockets events mechanism provided by the system.

Notes

  • The TTL attribute is optional. If not set, the parameter’s Value will persist indefinitely.

  • The expired event is only triggered when a TTL is set and the Value expires.

  • Parameters without a TTL will never expire unless explicitly modified.

This functionality allows for flexible and time-sensitive parameter management for robots in the system.