add reject() method to State trait

Author: polyactis

c17_state_pattern/src/lib.rs

@@ -20,6 +20,7 @@ impl Post {
     }
 
     pub fn request_review(&mut self) {
+        //self.state = Some(self.state.take().expect("Valid state").request_review());
         if let Some(s) = self.state.take() {
             self.state = Some(s.request_review())
         }
@@ -29,11 +30,31 @@ impl Post {
             self.state = Some(s.approve())
         }
     }
+
+    pub fn reject(&mut self) {
+        if let Some(s) = self.state.take() {
+            self.state = Some(s.reject())
+        }
+    }
 }
 
+
+/* 
+Note the capitalized "self" in Box<Self>.
+
+self is a keyword used within methods to represent the instance of the struct or enum on which the method is called.
+- It is similar to this in other languages.
+- It is a reference to the instance of the struct or enum on which the method is invoked.
+
+Self is a special type in Rust that represents the type of the implementing struct or enum itself. 
+- It is often used in trait definitions to refer to the type that is implementing the trait.
+- It is useful when you want to write generic code using traits and refer to the implementing type within the trait definition.
+*/
+
 trait State {
     fn request_review(self: Box<Self>) -> Box<dyn State>;
     fn approve(self: Box<Self>) -> Box<dyn State>;
+    fn reject(self: Box<Self>) -> Box<dyn State>;
     fn content<'a>(&self, _post: &'a Post) -> &'a str{
         ""
     }
@@ -49,6 +70,10 @@ impl State for Draft {
     fn approve(self: Box<Self>) -> Box<dyn State> {
         self
     }
+
+    fn reject(self: Box<Self>) -> Box<dyn State>{
+        self
+    }
 }
 
 struct PendingReview {}
@@ -60,6 +85,11 @@ impl State for PendingReview {
     fn approve(self: Box<Self>) -> Box<dyn State> {
         Box::new(Published {})
     }
+    fn reject(self: Box<Self>) -> Box<dyn State>{
+        Box::new(Draft{})
+
+    }
+
 }
 
 struct Published{}
@@ -75,4 +105,8 @@ impl State for Published {
     fn content<'a>(&self, post: &'a Post) -> &'a str {
         &post.content
     }
+
+    fn reject(self: Box<Self>) -> Box<dyn State>{
+        self
+    }
 }

c17_state_pattern/src/main.rs

@@ -5,10 +5,21 @@ fn main() {
 
     post.add_text("I ate a salad for lunch today");
     println!("Added text to the post.");
+    println!("Post content: {}", post.content());
     assert_eq!("", post.content());
 
     post.request_review();
     println!("Post review requested.");
+    println!("Post content: {}", post.content());
+    assert_eq!("", post.content());
+
+    post.reject();
+    println!("Post review rejected.");
+    println!("Post content: {}", post.content());
+
+    post.request_review();
+    println!("Post review requested.");
+    println!("Post content: {}", post.content());
     assert_eq!("", post.content());
 
     post.approve();