feature request: export AsyncLoader

[dakom]

Over time, I've come to find this struct is super helpful in all sorts of general scenarios.

It's defined internally in dominator as an example here:

rust-dominator/examples/async/src/util.rs

Line 27 in fc93afd

pub struct AsyncLoader {

I've copy/pasted/exported with permission here: https://docs.rs/dominator_helpers/0.8.0/dominator_helpers/futures/struct.AsyncLoader.html

However, that dominator_helpers crate doesn't really do much, and I often find myself importing it for just AsyncLoader

I think it's a good candidate to make part of dominator core

[Pauan]

I'm fine with exporting it, but I think it would be better suited to a different crate, since it's such a generic Future utility.

[dakom]

I do have it exported in a generic crate here (with attribution in the comments): https://docs.rs/awsm_web/latest/awsm_web/loaders/helpers/struct.AsyncLoader.html

But, there's a few problems:

1. That crate was my first Rust project, and the demo is currently broken, not a high priority for me to fix it. I'd be surprised if anyone other than myself really relies on it (though the crate itself is stable and heavily feature-gated... I could move AsyncLoader to a futures module so it's not buried among the other loader stuff)

2. The real reason - I'd be happy to change that to make it dominator-friendly without being dominator-specific, since it's great having is_loading be a Signal ... not sure how to go about that though... maybe it should return a Stream ?

All in all though, fwiw I'd prefer it in Dominator or futures-signals, feels to me like a very useful primitive like map_ref.