use_context_with to avoid expensive cloning of context

[finnbear]

Would it be possible to create use_context_with::<T, R>(observer: impl FnOnce(&T) -> R) -> R to avoid Cloneing the context for every component (as with use_context)?

I have a context struct with tons of callbacks, settings, etc. and I'm trying to avoid adding an Rc when I simply need to access one field out of it:

enum LanguageId {
    English,
    Spanish,
    French,
    ...
}

println!("{} bytes", std::mem::size_of::<GameContext>());
// 120 bytes

let language_id = use_context_with(|ctx: &GameContext| ctx.language_id)

I see a few alternatives, all of which are undesirable:

1. Creating a context for each of my 10+ fields would require a lot of boilerplate code to manage all the context providers
2. Using an Rc<LargeStruct> in my context seems like overkill when only a small part of the context can be copied out

Note: I posted on Discord before here: https://discord.com/channels/701068342760570933/703449306497024049/1020188734488055818

Note 2: This probably couldn't prevent all instances of Cloneing contexts, e.g. when rendering child components. However, if a component re-renders for reasons unrelated to a particular context, it would be nice to avoid Cloneing that context.