fix note about app_data

examples/application/src/mutable_state.rs

@@ -10,13 +10,14 @@ async fn index(data: web::Data<AppStateWithCounter>) -> String {
     let mut counter = data.counter.lock().unwrap(); // <- get counter's MutexGuard
     *counter += 1; // <- access counter inside MutexGuard
 
-    format!("Request number: {}", counter) // <- response with count
+    format!("Request number: {counter}") // <- response with count
 }
 // </setup_mutable>
 
 // <make_app_mutable>
 #[actix_web::main]
 async fn main() -> std::io::Result<()> {
+    // Note: web::Data created _outside_ HttpServer::new closure
     let counter = web::Data::new(AppStateWithCounter {
         counter: Mutex::new(0),
     });
@@ -24,7 +25,6 @@ async fn main() -> std::io::Result<()> {
     HttpServer::new(move || {
         // move counter into the closure
         App::new()
-            // Note: using app_data instead of data
             .app_data(counter.clone()) // <- register the created data
             .route("/", web::get().to(index))
     })

examples/application/src/state.rs

@@ -9,8 +9,7 @@ struct AppState {
 #[get("/")]
 async fn index(data: web::Data<AppState>) -> String {
     let app_name = &data.app_name; // <- get app_name
-
-    format!("Hello {}!", app_name) // <- response with app_name
+    format!("Hello {app_name}!") // <- response with app_name
 }
 // </setup>