Conditions

Rocketry’s scheduling system works with conditions that are either true or false. A simple condition could be time is now between 8 am and 2 pm (12-hour clock) or time is now between 08:00 and 14:00 (24-hour clock). If current time is inside this range, the condition is true and if not, then it’s false. If this is a condition for a task, the task is run if the the current time is in the range.

The conditions can be combinded using logical operations: AND, OR, NOT. They also can be nested using parentheses.

There are three ways of creating conditions in Rocketry:

  • Condition syntax

  • Condition API

  • Condition classes

All of the above generate condition instances that can be used as:

  • The start condition of a task (task starts if the condition is true)

  • The end condition of a task (task terminates if the condition is true and the task is running)

  • The shut condition of the scheduler (scheduler shuts down if the condition is true, useful in testing)

When evaluating a condition, the system uses method observe to get the state of the condition. You can test the status of a condition by:

>>> from rocketry.conds import time_of_day
>>> condition = time_of_day.between("10:00", "14:00")
>>> condition.observe()
True

The above returns True if your current time is between 10:00 (10 AM) and 14:00 (2 PM). Some conditions might rely on a task or the session (passed as .observe(task=task, session=session)).

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