Screen sequencers

A class responsible for the logic of the screen sequence. Works similarly to an iterator, returning the next screen when requested. The logic of the screen sequencer may or may not depend on the result of the previous screen.

Below is an example of a sequencer that returns a sequence of screens with some data that the user has to respond to (for example with a key press). If the user responds correctly, True is passed as the result, and the next returned screen is another screen with data. If the user responds incorrectly, False is passed as the result, and the next returned screen is a screen with a message. Then None is passed as the result to the message screen, and the next returned screen is another screen with data.

example sequencer logic

The methods must be called in the following order after initializing the sequencer:

  1. 1 call of get_next()

  2. 1 call of pass_previous_result()

  3. go back to step 1 until the sequencer is finished

When the sequencer is finished, it raises StopIteration.

Interface

class src.data_acquisition.sequencers.ScreenSequencer(*, logger: Logger | None = None)[source]

Bases: Generic[T], ABC

get_next() → EventfulScreen[T][source]
Returns:

The next screen in the sequence.

Raises:

  • IncorrectMethodCallOrderError – If the result of the previous screen was not provided (unless it’s the first screen).

  • StopIteration – If there is no next screen in the sequence.

pass_previous_result(result: T) → None[source]
Parameters:

result – The result of the previous screen.

Raises:

IncorrectMethodCallOrderError – If the result of the previous screen was already provided or before getting the first screen.

How to subclass

Subclasses should implement the following methods:

  • _get_next() -> EventfulScreen[T]

Available properties and methods:

  • _previous_result: T: the result of the previous screen.

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