coupling cohesion before

Author: diego-bearing

better-rust/Cargo.lock

@@ -1,4 +1,4 @@
-workspace = { members = ["solid", "macros"] }
+workspace = { members = ["solid", "macros", "coupling_and_cohesion"] }
 [package]
 name = "better-rust"
 version = "0.1.0"

better-rust/Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "coupling_and_cohesion"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+rand = "0.8.5"

better-rust/coupling_and_cohesion/Cargo.toml

@@ -0,0 +1,71 @@
+use rand::{self, Rng};
+
+fn generate_random_string(length: usize, digits: bool) -> String {
+    rand::thread_rng()
+        .sample_iter(rand::distributions::Alphanumeric)
+        .map(char::from)
+        .filter(|c| if digits { c.is_digit(10) } else { !c.is_digit(10) })
+        .map(|c| c.to_ascii_uppercase())
+        .take(length)
+        .collect()
+}
+
+pub struct VehicleRegistry;
+
+impl VehicleRegistry {
+    pub fn generate_vehicle_id(&self, length: usize) -> String {
+        generate_random_string(length, false)
+    }
+
+    pub fn generate_vehicle_license(&self, id: &str) -> String {
+        let front = &id[0..2];
+        let middle = generate_random_string(2, true);
+        let last = generate_random_string(2, false);
+
+        format!("{front}-{middle}-{last}")
+    }
+}
+
+pub struct Application;
+
+impl Application {
+    pub fn register_vehicle(&self, brand: &str) {
+        // create a registry instance
+        let registry = VehicleRegistry;
+
+        // generate a vehicle id of length 12
+        let vehicle_id = registry.generate_vehicle_id(12);
+
+        // now generate a license plate for the vehicle
+        // using the first two characters of the vehicle id
+        let license_plate = registry.generate_vehicle_license(&vehicle_id);
+
+        // compute the catalogue price
+        let mut catalogue_price = 0;
+
+        if brand == "Tesla Model 3" {
+            catalogue_price = 60000;
+        } else if brand == "Volkswagen ID3" {
+            catalogue_price = 35000;
+        } else if brand == "BMW 5" {
+            catalogue_price = 45000;
+        }
+
+        // compute the tax percentage (default 5% of the catalogue price, except for electric cars where it is 2%)
+        let mut tax_percentage = 0.05;
+
+        if brand == "Tesla Model 3" || brand == "Volkswagen ID3" {
+            tax_percentage = 0.02;
+        }
+
+        // compute the payable tax
+        let payable_tax = tax_percentage * catalogue_price as f32;
+
+        // print out the vehicle registration information
+        println!("Registration complete. Vehicle information:");
+        println!("Brand: {brand}");
+        println!("Id: {vehicle_id}");
+        println!("License plate: {license_plate}");
+        println!("Payable tax: {payable_tax:?}");
+    }
+}

better-rust/coupling_and_cohesion/src/coupling_cohesion_after.rs

@@ -0,0 +1,71 @@
+use rand::{self, Rng};
+
+fn generate_random_string(length: usize, digits: bool) -> String {
+    rand::thread_rng()
+        .sample_iter(rand::distributions::Alphanumeric)
+        .map(char::from)
+        .filter(|c| if digits { c.is_digit(10) } else { !c.is_digit(10) })
+        .map(|c| c.to_ascii_uppercase())
+        .take(length)
+        .collect()
+}
+
+pub struct VehicleRegistry;
+
+impl VehicleRegistry {
+    pub fn generate_vehicle_id(&self, length: usize) -> String {
+        generate_random_string(length, false)
+    }
+
+    pub fn generate_vehicle_license(&self, id: &str) -> String {
+        let front = &id[0..2];
+        let middle = generate_random_string(2, true);
+        let last = generate_random_string(2, false);
+
+        format!("{front}-{middle}-{last}")
+    }
+}
+
+pub struct Application;
+
+impl Application {
+    pub fn register_vehicle(&self, brand: &str) {
+        // create a registry instance
+        let registry = VehicleRegistry;
+
+        // generate a vehicle id of length 12
+        let vehicle_id = registry.generate_vehicle_id(12);
+
+        // now generate a license plate for the vehicle
+        // using the first two characters of the vehicle id
+        let license_plate = registry.generate_vehicle_license(&vehicle_id);
+
+        // compute the catalogue price
+        let mut catalogue_price = 0;
+
+        if brand == "Tesla Model 3" {
+            catalogue_price = 60000;
+        } else if brand == "Volkswagen ID3" {
+            catalogue_price = 35000;
+        } else if brand == "BMW 5" {
+            catalogue_price = 45000;
+        }
+
+        // compute the tax percentage (default 5% of the catalogue price, except for electric cars where it is 2%)
+        let mut tax_percentage = 0.05;
+
+        if brand == "Tesla Model 3" || brand == "Volkswagen ID3" {
+            tax_percentage = 0.02;
+        }
+
+        // compute the payable tax
+        let payable_tax = tax_percentage * catalogue_price as f32;
+
+        // print out the vehicle registration information
+        println!("Registration complete. Vehicle information:");
+        println!("Brand: {brand}");
+        println!("Id: {vehicle_id}");
+        println!("License plate: {license_plate}");
+        println!("Payable tax: {payable_tax:?}");
+    }
+}

better-rust/coupling_and_cohesion/src/coupling_cohesion_before.rs

@@ -0,0 +1,7 @@
+mod coupling_cohesion_before;
+
+fn main() {
+    let app = coupling_cohesion_before::Application;
+
+    app.register_vehicle("Volkswagen ID3");
+}