4 files changed, 111 insertions, 0 deletions
diff --git a/src/doc/book/listings/ch17-oop/listing-17-16/Cargo.lock b/src/doc/book/listings/ch17-oop/listing-17-16/Cargo.lock
new file mode 100644
index 000000000..b6f4232c6
--- /dev/null
+++ b/src/doc/book/listings/ch17-oop/listing-17-16/Cargo.lock
@@ -0,0 +1,6 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+[[package]]
+name = "blog"
+version = "0.1.0"
+
diff --git a/src/doc/book/listings/ch17-oop/listing-17-16/Cargo.toml b/src/doc/book/listings/ch17-oop/listing-17-16/Cargo.toml
new file mode 100644
index 000000000..1619af5c6
--- /dev/null
+++ b/src/doc/book/listings/ch17-oop/listing-17-16/Cargo.toml
@@ -0,0 +1,6 @@
+[package]
+name = "blog"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
diff --git a/src/doc/book/listings/ch17-oop/listing-17-16/src/lib.rs b/src/doc/book/listings/ch17-oop/listing-17-16/src/lib.rs
new file mode 100644
index 000000000..92cb29813
--- /dev/null
+++ b/src/doc/book/listings/ch17-oop/listing-17-16/src/lib.rs
@@ -0,0 +1,85 @@
+pub struct Post {
+    state: Option<Box<dyn State>>,
+    content: String,
+}
+
+// ANCHOR: here
+impl Post {
+    // --snip--
+    // ANCHOR_END: here
+    pub fn new() -> Post {
+        Post {
+            state: Some(Box::new(Draft {})),
+            content: String::new(),
+        }
+    }
+
+    pub fn add_text(&mut self, text: &str) {
+        self.content.push_str(text);
+    }
+
+    pub fn content(&self) -> &str {
+        ""
+    }
+
+    pub fn request_review(&mut self) {
+        if let Some(s) = self.state.take() {
+            self.state = Some(s.request_review())
+        }
+    }
+
+    // ANCHOR: here
+    pub fn approve(&mut self) {
+        if let Some(s) = self.state.take() {
+            self.state = Some(s.approve())
+        }
+    }
+}
+
+trait State {
+    fn request_review(self: Box<Self>) -> Box<dyn State>;
+    fn approve(self: Box<Self>) -> Box<dyn State>;
+}
+
+struct Draft {}
+
+impl State for Draft {
+    // --snip--
+    // ANCHOR_END: here
+    fn request_review(self: Box<Self>) -> Box<dyn State> {
+        Box::new(PendingReview {})
+    }
+
+    // ANCHOR: here
+    fn approve(self: Box<Self>) -> Box<dyn State> {
+        self
+    }
+}
+
+struct PendingReview {}
+
+impl State for PendingReview {
+    // --snip--
+    // ANCHOR_END: here
+    fn request_review(self: Box<Self>) -> Box<dyn State> {
+        self
+    }
+
+    // ANCHOR: here
+    fn approve(self: Box<Self>) -> Box<dyn State> {
+        Box::new(Published {})
+    }
+}
+
+struct Published {}
+
+impl State for Published {
+    fn request_review(self: Box<Self>) -> Box<dyn State> {
+        self
+    }
+
+    fn approve(self: Box<Self>) -> Box<dyn State> {
+        self
+    }
+}
+// ANCHOR_END: here
diff --git a/src/doc/book/listings/ch17-oop/listing-17-16/src/main.rs b/src/doc/book/listings/ch17-oop/listing-17-16/src/main.rs
new file mode 100644
index 000000000..14b4c0824
--- /dev/null
+++ b/src/doc/book/listings/ch17-oop/listing-17-16/src/main.rs
@@ -0,0 +1,14 @@
+use blog::Post;
+
+fn main() {
+    let mut post = Post::new();
+
+    post.add_text("I ate a salad for lunch today");
+    assert_eq!("", post.content());
+
+    post.request_review();
+    assert_eq!("", post.content());
+
+    post.approve();
+    assert_eq!("I ate a salad for lunch today", post.content());
+}