feat: ✨ enforce rules by defining restrictive custom types

25-validation_types/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "validation_types"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

25-validation_types/src/lib.rs

@@ -0,0 +1,41 @@
+// This is our type to enforce some rules
+// Since struct itself is public and word inside of it private
+// we're able to create TahinliWord everywhere but
+// can't modify it's value (word) outside of this module
+// This will allow us to apply some rules
+pub struct TahinliWord {
+    word: String,
+}
+
+impl TahinliWord {
+    // This's basically a validator that enforces TahinliWord rules
+    // Since this is private I'm only using it in this module for clean code
+    fn validator(word: &String) -> bool {
+        match word.as_str() {
+            "Tahinli" | "tahinli" | "TAHINLI" => true,
+            _ => false,
+        }
+    }
+
+    // This is one and only function that allow user to create new TahinliWord
+    // Thanks to this situation we're able to check whatever we want
+    pub fn new(word: String) -> Self {
+        TahinliWord::validator(&word);
+        TahinliWord { word }
+    }
+
+    // This is a getter method that only exposes it's value
+    pub fn get(&self) -> &String {
+        &self.word
+    }
+
+    // This is a setter method that's the only way to edit existing TahinliWord
+    // This gives us power to do whatever check we want
+    pub fn set(&mut self, word: String) {
+        if TahinliWord::validator(&word) {
+            self.word = word;
+        } else {
+            panic!("\"{}\" is not a Tahinli Word", word);
+        }
+    }
+}

25-validation_types/src/main.rs

@@ -0,0 +1,19 @@
+use validation_types::TahinliWord;
+
+fn main() {
+    println!("Hello, world!");
+
+    // This will create new TahinliWord type
+    let mut tahinli_word = TahinliWord::new("Tahinli".to_string());
+    // This will print like normal string
+    println!("{}", tahinli_word.get());
+
+    // Borrow checker not allow to manipulate it
+    // It's read only value
+    // let mut try_to_manipulate = tahinli_word.get();
+    // try_to_manipulate.clear();
+
+    // This will try to bypass Tahinli Word rules and panic
+    tahinli_word.set("This is not a Tahinli Word".to_string());
+    println!("Code won't run this line :/");
+}