Function create_action 

pub fn create_action<I, O, F, Fu>(action_fn: F) -> Action<I, O>
where
    I: Send + Sync + 'static,
    O: Send + Sync + 'static,
    F: Fn(&I) -> Fu + Send + Sync + 'static,
    Fu: Future<Output = O> + Send + 'static,

👎Deprecated: This function is being removed to conform to Rust idioms. Please use Action::new() instead.

Creates a new action. This is lazy: it does not run the action function until some value is dispatched.

The constructor takes a function which will create a new Future from some input data. When the action is dispatched, this action_fn will run, and the Future it returns will be spawned.

The action_fn must be Send + Sync so that the ArcAction is Send + Sync. The Future must be Send so that it can be moved across threads by the async executor as needed. In order to be stored in the Copy arena, the input and output types should also be Send + Sync.

let act = Action::new(|n: &u8| {
    let n = n.to_owned();
    async move { n * 2 }
});

act.dispatch(3);
assert_eq!(act.input().get(), Some(3));

// Remember that async functions already return a future if they are
// not `await`ed. You can save keystrokes by leaving out the `async move`

let act2 = Action::new(|n: &String| yell(n.to_owned()));
act2.dispatch(String::from("i'm in a doctest"));

// after it resolves
assert_eq!(act2.value().get(), Some("I'M IN A DOCTEST".to_string()));

async fn yell(n: String) -> String {
    n.to_uppercase()
}