Using an async fn in set_on_submit

[nhtyy]

trying to get this to work any suggestions?

Code that calls the callback

    pub fn set_on_submit<F, R, V: ?Sized>(&mut self, cb: F)
    where
        F: 'static + Fn(&mut Cursive, &V) -> R,
        T: Borrow<V>,
    {
        self.on_submit = Some(Rc::new(move |s, t| {
            cb(s, t.borrow());
        }));
    }

example callback using tokio as runtime btw

async fn handle_function_call<F>(siv: &mut Cursive, func: &F) {
   // work work work
  ()
}

example error (note the expected and found match??)
"mismatched types expected trait `for<'r, 's> <for<'r, 's> fn(&'r mut Cursive, &'s AryaFunction) -> impl for<'r, 's> Future<Output = ()> {handle_function_call::<AryaFunction>} as FnOnce<(&'r mut Cursive, &'s AryaFunction)>>`\n found trait `for<'r, 's> <for<'r, 's> fn(&'r mut Cursive, &'s AryaFunction) -> impl for<'r, 's> Future<Output = ()> {handle_function_call::<AryaFunction>} as FnOnce<(&'r mut Cursive, &'s AryaFunction)>>`",

adding lifetime bounds

async fn handle_function_call<'r, 's, F>(siv: &'r mut Cursive, func: &'s F) {
   // work work work
  ()
}

yields same error

[gyscos]

Hi, and thanks for the question!

At the moment cursive is not async aware.
This means that most views use non-async functions for callbacks.
What you can do instead is to use a regular closure in which you spawn an async task (and possibly wait for completion if you need a result there, but ideally not).

Now one issue is if you need to borrow &mut Cursive. It'd be easier if you didn't.
You should instead:

• In the (non async) callback closure, first get anything you need from the &mut Cursive(state from other views, maybe clone itscb_sink`, ...).
• Spawn an async task to run async processing (maybe network connections). You would move the stuff you need there. This async task would not take any reference to Cursive and ideally would be 'static.
• Return from the callback, with the async task still running. Optionally indicate that a background operation is running (show a popup for instance, or lock the UI to avoid receiving another submit callback before the current task completes).
• From the async task, use the cloned cb_sink to report the results to the UI.

Overall it's very similar to using a background thread, but using an async task instead.

[nhtyy]

Hey thanks for the edit, appreciate your time!