Conditionally using wakepy modes

[fohrloop]

It's probably quite usual use case to do something like:

if some_flag:
    with keep.running():
        do_something()
else:
    do_something()

I thought first that there could be some conditional flag added to the modes, like

with keep.running(only_if=some_flag):
    do_something()

but that raises questions like: What does "success" mean here is the flag is set and the mode is not entered?

It would be probably enough to document a recipe for conditionally using a wakepy mode using the solution from the standard library: nullcontext -- which conveniently supports Python 3.7+ (all versions which wakepy supports). The recipe is:

mode = keep.running() if some_flag else contextlib.nullcontext()

with mode:
    do_something()

EDIT: The nullcontext is not a 100% drop-in replacement as you cannot do, for example:

mode = keep.running() if some_flag else contextlib.nullcontext()

with mode as m:
    print('Used method:', m.used_method)
    do_something()

because the with statement target (m) does will be a Mode instance when using keep.running() and None by default when using the nullcontext. As the nullcontext gives any input argument as the with statement target, there it could be:

import contextlib
from wakepy import keep, DummyMode

mode = keep.running() if some_flag else contextlib.nullcontext(DummyMode())

with mode:
    do_something()

This already needs two imports and requires that the user knows about the contextlib.nullcontext. It would be probably more user-friendly to provide the dummy / no-op mode from wakepy, so one could write:

from wakepy import keep, DummyMode

mode = keep.running() if some_flag else DummyMode()

with mode:
    do_something()

Questions to be answered:

1. What is the nicest name for this?

• DummyMode -> usage: DummyMode()
• dummy_mode -> usage: dummy_mode() (function)
• dummy_mode -> usage: dummy_mode (instance of Mode. Does nothing. Reusable)
• dummy or dummy() or dummymode or dummymode()
• noop: usage: noop() or noop
• noop_mode / noop_mode()
• others?

2. What attributes/attribute values the DummyMode should have?

From the docs, the Modes have the following attributes (among others):

• m.active: True, if entering mode was successful. --> Should be True?
• m.active_method: The name of the active method. Will be None after mode is deactivated. -- should be same as in used_method
• m.used_method: The name of the used method. Will not be reset to None after deactivation. -- should be just "Dummy" or "No-op"?
• m.activation_result: An ActivationResult instance which gives more detailed information about the activation process. -- needs thinking

3. Is this any better than using keep.running(only_if=some_flag)?

This is starting to become more complicated. Would the initial idea be simper from the user's perspective?

Task

• Design how to conditionally use wakepy modes
• Implement the solution

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Comments / suggestions welcome!