From 698f8c2f01ea549d77d7dc3338a12e04c11057b9 Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Wed, 17 Apr 2024 14:02:58 +0200
Subject: Adding upstream version 1.64.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
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 src/doc/book/redirects/trait-objects.md | 68 +++++++++++++++++++++++++++++++++
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+% Trait Objects
+
+<small>There is a new edition of the book and this is an old link.</small>
+
+> Trait objects combine the data made up of the pointer to a concrete object with the behavior of the methods defined in the trait.
+> A trait defines behavior that we need in a given situation.
+> We can then use a trait as a trait object in places where we would use a concrete type or a generic type.
+
+```rust,ignore
+pub struct InputBox {
+    pub label: String,
+}
+
+impl Draw for InputBox {
+    fn draw(&self) {
+        // Code to actually draw an input box
+    }
+}
+
+pub struct Button {
+    pub label: String,
+}
+
+impl Draw for Button {
+    fn draw(&self) {
+        // Code to actually draw a button
+    }
+}
+
+pub struct Screen<T: Draw> {
+    pub components: Vec<T>,
+}
+
+impl<T> Screen<T>
+    where T: Draw {
+    pub fn run(&self) {
+        for component in self.components.iter() {
+            component.draw();
+        }
+    }
+}
+
+fn main() {
+    let screen = Screen {
+        components: vec![
+            Box::new(InputBox {
+                label: String::from("OK"),
+            }),
+            Box::new(Button {
+                label: String::from("OK"),
+            }),
+        ],
+    };
+
+    screen.run();
+}
+```
+
+---
+
+Here are the relevant sections in the new and old books:
+
+* **[in the current edition: Ch 17.02 — Trait Objects][2]**
+* <small>[In the first edition: Ch 3.22 — Trait Objects][1]</small>
+
+
+[1]: https://doc.rust-lang.org/1.30.0/book/first-edition/trait-objects.html
+[2]: ch17-02-trait-objects.html
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