Updated 'src/oop/implementing.md'.

projects/blog/src/lib.rs

@@ -1,74 +1,43 @@
 pub struct Post {
-    state: Option<Box<dyn State>>,
+    content: String,
+}
+
+pub struct DraftPost {
     content: String,
 }
 
 impl Post {
-    pub fn new() -> Post {
-        Post {
-            state: Some(Box::new(Draft {})),
+    pub fn new() -> DraftPost {
+        DraftPost {
             content: String::new(),
         }
     }
 
+    pub fn content(&self) -> &str {
+        &self.content
+    }
+}
+
+impl DraftPost {
     pub fn add_text(&mut self, text: &str) {
         self.content.push_str(text);
     }
 
-    pub fn content(&self) -> &str {
-        self.state.as_ref().unwrap().content(self)
-    }
-
-    pub fn request_review(&mut self) {
-        if let Some(s) = self.state.take() {
-            self.state = Some(s.request_review())
-        }
-
-        pub fn approve(&mut self) {
-            if let Some(s) = self.state.take() {
-                self.state = Some(s.approve())
-            }
+    pub fn request_review(self) -> PendingReviewPost {
+        PendingReviewPost {
+            content: self.content,
         }
     }
-
-    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 {
-    fn request_review(self: Box<Self>) -> Box<dyn State> {
-        Box::new(PendingReview {})
-    }
-
-    fn approve(self: Box<Self>) -> Box<dyn State> {
-        self
-    }
+pub struct PendingReviewPost {
+    content: String,
 }
 
-struct PendingReview {}
-
-impl State for PendingReview {
-    fn request_review(self: Box<Self>) -> Box<dyn State> {
-        self
-    }
-
-    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
+impl PendingReviewPost {
+    pub fn approve(self) -> Post {
+        Post {
+            content: self.content,
+        }
     }
 }

projects/blog/src/main.rs

@@ -0,0 +1,21 @@
+use blog::Post;
+use std::any::type_name;
+
+fn main() {
+    let mut post = Post::new();
+    println! ("{}", type_name_of_val(&post));
+
+    post.add_text("今天午饭我吃了沙拉。");
+
+    let post = post.request_review();
+    println! ("{}", type_name_of_val(&post));
+
+    let post = post.approve();
+    println! ("{}", type_name_of_val(&post));
+
+    assert_eq! ("今天午饭我吃了沙拉。", post.content());
+}
+
+fn type_name_of_val<T>(_: &T) -> &'static str {
+    type_name::<T>()
+}

projects/neo_simple_blog/Cargo.toml

@@ -1,8 +0,0 @@
-[package]
-name = "neo_simple_blog"
-version = "0.1.0"
-edition = "2021"
-
-# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
-
-[dependencies]

projects/neo_simple_blog/src/lib.rs

@@ -1,43 +0,0 @@
-pub struct Post {
-    content: String,
-}
-
-pub struct DraftPost {
-    content: String,
-}
-
-impl Post {
-    pub fn new() -> DraftPost {
-        DraftPost {
-            content: String::new(),
-        }
-    }
-
-    pub fn content(&self) -> &str {
-        &self.content
-    }
-}
-
-impl DraftPost {
-    pub fn add_text(&mut self, text: &str) {
-        self.content.push_str(text);
-    }
-
-    pub fn request_review(self) -> PendingReviewPost {
-        PendingReviewPost {
-            content: self.content,
-        }
-    }
-}
-
-pub struct PendingReviewPost {
-    content: String,
-}
-
-impl PendingReviewPost {
-    pub fn approve(self) -> Post {
-        Post {
-            content: self.content,
-        }
-    }
-}

projects/neo_simple_blog/src/main.rs

@@ -1,15 +0,0 @@
-#![allow(dead_code)]
-#![allow(unused_variables)]
-
-use neo_simple_blog::Post;
-
-fn main() {
-    let mut post = Post::new();
-
-    post.add_text("这是一个博客帖子。");
-
-    let post = post.request_review();
-    let post = post.approve();
-
-    assert_eq! ("这是一个博客帖子。", post.content());
-}