-// Rust-101, Part 11: Trait Objects, Box, Rc, Lifetime bounds
-// ==========================================================
+// Rust-101, Part 11: Trait Objects, Box, Lifetime bounds
+// ======================================================
-mod callbacks {
- // For now, we just decide that the callbacks have an argument of type `i32`.
- struct CallbacksV1<F: FnMut(i32)> {
- callbacks: Vec<F>,
- }
-
- /* struct CallbacksV2 {
- callbacks: Vec<FnMut(i32)>,
- } */
- pub struct Callbacks {
- callbacks: Vec<Box<FnMut(i32)>>,
- }
+// For now, we just decide that the callbacks have an argument of type `i32`.
+struct CallbacksV1<F: FnMut(i32)> {
+ callbacks: Vec<F>,
+}
- impl Callbacks {
- // Now we can provide some functions. The constructor should be straight-forward.
- pub fn new() -> Self {
- unimplemented!()
- }
+/* struct CallbacksV2 {
+ callbacks: Vec<FnMut(i32)>,
+} */
- // Registration simply stores the callback.
- pub fn register(&mut self, callback: Box<FnMut(i32)>) {
- unimplemented!()
- }
+pub struct Callbacks {
+ callbacks: Vec<Box<FnMut(i32)>>,
+}
- // And here we call all the stored callbacks.
- pub fn call(&mut self, val: i32) {
- // Since they are of type `FnMut`, we need to mutably iterate. Notice that boxes dereference implicitly.
- for callback in self.callbacks.iter_mut() {
- unimplemented!()
- }
- }
+impl Callbacks {
+ // Now we can provide some functions. The constructor should be straight-forward.
+ pub fn new() -> Self {
+ unimplemented!()
}
- // Now we are ready for the demo.
- pub fn demo(c: &mut Callbacks) {
- c.register(Box::new(|val| println!("Callback 1: {}", val)));
- c.call(0);
-
- let mut count: usize = 0;
- c.register(Box::new(move |val| {
- count = count+1;
- println!("Callback 2, {}. time: {}", count, val);
- } ));
- c.call(1); c.call(2);
+ // Registration simply stores the callback.
+ pub fn register(&mut self, callback: Box<FnMut(i32)>) {
+ self.callbacks.push(callback);
}
-}
-// Remember to edit `main.rs` to run the demo.
-pub fn main() {
- let mut c = callbacks::Callbacks::new();
- callbacks::demo(&mut c);
-}
-
-mod callbacks_clone {
-
- use std::rc::Rc;
-
- #[derive(Clone)]
- pub struct Callbacks {
- callbacks: Vec<Rc<Fn(i32)>>,
+ // We can also write a generic version of `register`, such that it will be instantiated with some concrete closure type `F`
+ // and do the creation of the `Box` and the conversion from `F` to `FnMut(i32)` itself.
+
+ pub fn register_generic<F: FnMut(i32)+'static>(&mut self, callback: F) {
+ unimplemented!()
}
- impl Callbacks {
- pub fn new() -> Self {
- unimplemented!()
- }
-
- // For the `register` function, we don't actually have to use trait objects in the argument.
-
- pub fn register<F: Fn(i32)+'static>(&mut self, callback: F) {
+ // And here we call all the stored callbacks.
+ pub fn call(&mut self, val: i32) {
+ // Since they are of type `FnMut`, we need to mutably iterate.
+ for callback in self.callbacks.iter_mut() {
unimplemented!()
}
-
- pub fn call(&mut self, val: i32) {
- // We only need a shared iterator here. `Rc` also implicitly dereferences, so we can simply call the callback.
- for callback in self.callbacks.iter() {
- unimplemented!()
- }
- }
}
+}
+
+// Now we are ready for the demo. Remember to edit `main.rs` to run it.
+pub fn main() {
+ let mut c = Callbacks::new();
+ c.register(Box::new(|val| println!("Callback 1: {}", val)));
+ c.call(0);
- // The demo works just as above. Our counting callback doesn't work anymore though, because we are using `Fn` now.
- fn demo(c: &mut Callbacks) {
- c.register(|val| println!("Callback 1: {}", val));
- c.call(0); c.call(1);
+ {
+ let mut count: usize = 0;
+ c.register_generic(move |val| {
+ count = count+1;
+ println!("Callback 2: {} ({}. time)", val, count);
+ } );
}
+ c.call(1); c.call(2);
}
+
// **Exercise 11.1**: We made the arbitrary choice of using `i32` for the arguments. Generalize the data-structures above
// to work with an arbitrary type `T` that's passed to the callbacks. Since you need to call multiple callbacks with the
// same `t: T`, you will either have to restrict `T` to `Copy` types, or pass a borrow.
-
projects / rust-101.git / blobdiff