Rename: OnEditor invalid to sentinel

[ColinWttt]

#[init(invalid= val)] -> #[init(sentinel = val)]
OnEditor::new_invalid(val) -> OnEditor::from_sentinel(val)

[Bromeon]

Thanks!

As mentioned in #1051 (review), "invalid" is not yet the final name -- we should probably decide on one and then adapt it everywhere. Maybe we can use this PR for some suggestions 🤔

Some ideas I had a while ago:

I'm not really sure about the name "uninit" in OnEditor::unit() + #[init(uninit = ...)]. First, people probably know this from mem::MaybeUninit::uninit(), where it has a totally different meaning (actually uninitialized memory).

Second, it doesn't express that the value is not only "uninitialized", but also a "invalid marker" for value that's used to distinguish valid/invalid state. In programming, sentinel value probably comes close to describe it.

I don't really have a great alternative though, maybe we can brainstorm a bit?

• Single word: unset, invalid, ...
• Marker: invalid_marker, uninit_marker
• Sentinel: uninit_sentinel, ...
• Descriptive: needs_init
• Exclusion: except, exclude, excluded, exempt, unless...

(Perfect would be a single word expressing both "needs initialization" and "marks an invalid value", but that's very specific...)

My personal favorites:

#[init(sentinel = 7)] // 'sentinel value' is a semi-known term

OnEditor::uninit_sentinel(7) // naming?

#[init(unless = 7)] // consider initialized, unless it's 7

OnEditor::init_unless(7)

It doesn't seem like there's a simple enough term that makes the semantics 100% clear, so reading docs will be necessary anyway. That considered, distinction from other well-known concepts ("uninit" like MaybeUninit::uninit, or "invalid" like Plane::invalid) reduces confusion.

[ColinWttt]

Second, it doesn't express that the value is not only "uninitialized", but also a "invalid marker" for value that's used to distinguish valid/invalid state. In programming, sentinel value probably comes close to describe it.

Sentinel looks pretty cool. As a non-native English speaker, I prefer some simple words like dummy, placeholder, and fake.

[Yarwin]

I think sentinel is way to go 👍, albeit dummy is a bit more descriptive (it literally stands for "dummy value displayed in the editor")

Personally I would go with OnEditor::with/new_sentinel(val) as stated in RFC-0430: finalizing-naming-conventions.

[Bromeon]

In OnReady, we use different constructors though:

• new
• node
• manual
• from_base_fn

So with_sentinel would be yet another convention.
Maybe OnReady ones should at some point be updated; node could probably be from_node.

Regarding this pull request, what about OnEditor::from_sentinel?

#[init(sentinel = 7)] 

OnEditor::from_sentinel(7)

[GodotRust]

API docs are being generated and will be shortly available at: https://godot-rust.github.io/docs/gdext/pr-1079

[Bromeon]

Thanks a lot, and congrats to your first merged PR! 😊