Flyout: use theme default for position

[humitos]

Initial POC to prove if this idea is possible and how we feel about it.

I put together an example of what I understand we want to build here 😅 . In this example, the theme author will make explicitly how they want to use readthedocs-flyout HTML tag:

<readthedocs-flyout position="top-right"></readthedocs-flyout>

That will add the class top-right and show the flyout as follows:

However, the project author can change the position value from the dashboard if they prefer to override the theme's default value:

• Related Customization patterns #51
• Requires Addons: add "flyout position" to the form ext-theme#554
• Requires Addons: allow to set a "Default" or a explicit position for flyout readthedocs.org#11891
• Example using https://test-builds.readthedocs.io/en/addons-theme-defaults/
• Closes Implement POC for theme default options #434

[ericholscher]

Seems clearer to set this in an if, instead of resetting the value to itself?

[ericholscher]

Suggested change

	this.position =
	objectPath.get(this.config, "addons.flyout.position", null) ||
	this.position;
	position = objectPath.get(this.config, "addons.flyout.position", null);
	if position:
	this.position = position;

[humitos]

My reading is "get the value from the API or keep the actual one".

I don't have a strong preference, but happy to change it if wanted.

[ericholscher]

I don't feel super strongly, but think it's more explicit. Setting a value to itself is odd to me?

[agjohnson]

position is a reactive property, so it's best to avoid triggering unneeded updates to the property. Wrapping this with a conditional is probably best. Otherwise this pattern for setting variable defaults is pretty common though.

[humitos]

@agjohnson I would appreciate your review on this PR so we can decide whether or not move forward with this implementation.

[agjohnson]

position is a reactive property, so it's best to avoid triggering unneeded updates to the property. Wrapping this with a conditional is probably best. Otherwise this pattern for setting variable defaults is pretty common though.