encapsulation

src/advance/encapsulation.py

@@ -0,0 +1,60 @@
+class Car:
+    def __init__(self, brand, price):
+        self.brand = brand         # Public attribute
+        self._engine = "V8"        # Protected
+        self.__price = price       # Private
+
+    # Public method
+    def start(self):
+        print(f"{self.brand} started with {self._engine} engine.")
+
+    # Getter for private attribute
+    def get_price(self):
+        return self.__price
+
+    # Setter for private attribute
+    def set_price(self, new_price):
+        if new_price > 0:
+            self.__price = new_price
+        else:
+            print("Invalid price!")
+
+
+car = Car("BMW", 50000)
+
+print(car.brand)  # Public
+print(car._engine)    # Possible, but not recommended
+# print(car.__price)  #  AttributeError
+
+print(car.get_price())   # calling getter
+car.set_price(60000)
+print(car.get_price())
+
+
+# ------------------------------------------------------------
+# Encapsulation with @ property (Pythonic Way)
+
+class BankAccount:
+    def __init__(self, balance):
+        self.__balance = balance   # Private
+
+    @property
+    def balance(self):
+        return self.__balance
+
+    @balance.setter
+    def balance(self, new_amount):
+        if new_amount > 0:
+            self.__balance = new_amount
+        else:
+            print("Balance cannot be negative.")
+            raise ValueError("Balance cant be negative")
+
+
+acc = BankAccount(1000)
+print(acc.balance)
+
+acc.balance = 2000    # Calls setter
+print(acc.balance)
+
+# acc.balance = -500