Function middleware_fn 

pub fn middleware_fn<T, F>(f: F) -> impl HandlerMiddleware<T>
where
    T: Send + Sync + 'static,
    F: Fn(Arc<dyn MessageHandler<T>>) -> Arc<dyn MessageHandler<T>> + Send + Sync + 'static,

Adapter that turns a closure into a HandlerMiddleware.

Useful for simple one-off middleware that do not need their own struct.

Example

use rskit_messaging::handler::middleware_fn;
use std::sync::Arc;

let mw = middleware_fn(|next| {
    // wrap next handler with custom behaviour
    next
});