Add a clear method that removes all children.

[malikoth]

Fixes #1828

PR Checklist:

• All new features have been tested
• All new features have been documented
• I have read the CONTRIBUTING.md file
• I will abide by the code of conduct

[freakboy3742]

This implementation looks good; now we just need the rest of the owl :-)

Two pieces are missing:

1. A change note - a file in the changes directory that provides the release note for this improvement. See the contribution guide for details on what is needed
2. A test. core/tests/widgets/test_base.py has a suite of tests validating that child removal works; we need an additional set of tests for this new API. We need to validate that clear works for (a) a widget that has children, (b) a widget that can have children, but doesn't; and (c) a leaf node that can't have children.

[malikoth]

Yup, just working through the contribution guide, little bit at a time. :)

[malikoth]

The base widget documentation includes this block:

Reference
---------

.. autoclass:: toga.widgets.base.Widget
   :members:
   :undoc-members:
   :inherited-members:

Am I to understand that this will automatically slurp up the docstring of my new method and I don't need to manually do anything for this new method to be documented?

[malikoth]

@freakboy3742 I think this is ready for re-review. よろしくお願いします!

[malikoth]

OK, so the Travertino Widget.clear docs say that calling clear on a leaf node raises ValueError. My code does not do that, but then again... despite what the docs say, neither does Widget.clear. What is the best resolution?

Raising the error is preferable to silently doing a noop, right?

[freakboy3742]

Looks good to me! Thanks for the fix!

[wafaa09]

Hello! I don't mean to be inpatient, but if this feature will be done soon, I also don't want to spend time completing my project when this is exactly what I need! Is there a timeline for completion? I saw that there were a couple things left to do, but not sure how long that will take.
Thank you!

[freakboy3742]

@wafaa09 Umm... the PR has been merged. It's done. It hasn't been released in a stable release of Toga, but there's no more work to be done. If you want a pre-release version you can install the main branch of Toga from the git repository.

[wafaa09]

Awesome, thank you for letting me know!