comparision between coupling and cohesion

dependency-injection/betterpython/coupling_cohesion_after.py

@@ -0,0 +1,76 @@
+
+
+import string
+import random
+
+class VehicleInfo:
+
+    def __init__(self,brand, electric, catalogue_price) -> None:
+        self.brand = brand
+        self.electric = electric
+        self.catalogue_price = catalogue_price
+
+    def compute_tax(self):
+        tax_percentage = 0.05
+        if self.electric:
+            tax_percentage = 0.02
+        return tax_percentage
+
+    def print(self):
+        print("Registration complete. Vehicle information:")
+        print(f"Brand : {self.brand}")
+        print(f"Payable tax: {self.payable_tax}")
+
+class Vehicle:
+
+    def __init__(self,id, license_plate, info:VehicleInfo) -> None:
+        self.id = id
+        self.license_plate = license_plate
+        self.info = info
+
+    def print(self):
+        print(f"Id : {self.id}")
+        print(f"License plate: {self.license_plate}")
+        self.info.print()
+
+class VehicleRegistry:
+
+    def __init__(self):
+        self.vehicle_info = {}
+        self.add_vehicle_info("Tesla Model 3", True, 60000)
+        self.add_vehicle_info("Volkswagen ID3", True, 35000)
+        self.add_vehicle_info("BMW 5", False, 45000)
+        self.add_vehicle_info("Tesla Model Y", True, 75000)
+
+
+    def add_vehicle_info(self, brand, electric, catalogue_price):
+        self.vehicle_info[brand] = VehicleInfo(brand, electric, catalogue_price)
+
+    def generate_vehicle_id(self, length):
+        return ''.join(random.choices(string.ascii_uppercase, k=length))
+
+    def generate_vehicle_license(self, id):
+        return f"{id[:2]}-{''.join(random.choices(string.digits, k=2))}-{''.join(random.choices(string.ascii_uppercase, k=2))}"
+
+    def create_vehicle(self, brand):
+        id = self.generate_vehicle_id(12)
+        license_plate = self.generate_vehicle_license(id)
+        return Vehicle(id, license_plate, self.vehicle_info[brand])
+
+
+class Application:
+
+    def register_vehicle(self,brand:string):
+
+        # create a registry instance
+        registry = VehicleRegistry()
+
+        vehicle = registry.create_vehicle(brand)
+
+        # print out the vehicle information
+        vehicle.print()
+
+
+app = Application()
+app.register_vehicle('BMW 5')
+

dependency-injection/betterpython/coupling_cohesion_before.py

@@ -0,0 +1,59 @@
+
+
+import string
+import random
+
+
+class VehicleRegistry:
+
+    def generate_vehicle_id(self,length):
+        return ''.join(random.choices(string.ascii_uppercase, k=length))
+
+    def generate_vehicle_license(self,id):
+        return f"{id[:2]}-{''.join(random.choices(string.digits,k=2))}-{''.join(random.choices(string.ascii_uppercase,k=2))}"
+
+
+
+class Application:
+
+    def register_vehicle(self,brand:string):
+
+        # create a resistry instance    
+        registry = VehicleRegistry()
+
+        # generate a vehicle id of length of 12
+        vehicle_id = registry.generate_vehicle_id(12)
+
+        # now generate a license plate for the vehicle
+        # using the first two characters of the vehicle id
+        license_plate = registry.generate_vehicle_license(vehicle_id)
+
+        # compute the catalogue price
+        catalogue_price =0
+
+        if brand == 'Tesla' :
+            catalogue_price = 6000
+        elif brand == 'Volkswagen':
+            catalogue_price = 3500
+        elif brand == 'BMW':
+            catalogue_price = 4500
+
+        # compute the tax percentage (default 5% of the catalogue price, except for electric cars where it is 2%)
+        tax_percentage = 0.05
+        if brand == 'Tesla' or brand == 'Volkswagen':
+            tax_percentage = 0.02
+
+
+        #compute the payable tax 
+        payable_tax = tax_percentage * catalogue_price
+
+        #print out the vehicle registration information
+        print("Registration complete. Vehicle information:")
+        print(f"Brand : {brand}")
+        print(f"Id : {vehicle_id}")
+        print(f"License plate: {license_plate}")
+        print(f"Payable tax: {payable_tax}")
+
+app = Application()
+app.register_vehicle('Tesla')
+