Adding Chapter 3 files

Chapter3/classes/carexample1.py

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+#carexample1.py
+class Car:
+    pass
+
+if __name__ == "__main__":
+    car = Car ()
+    car.color = "blue"
+    car.miles = 1000
+    print (car.color)
+    print (car.miles)

Chapter3/classes/carexample2.py

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+#carexample2.py
+class Car:
+    c_mileage_units = "Mi"
+    def __init__(self, color, miles):
+        self.i_color = color
+        self.i_mileage = miles
+
+if __name__ == "__main__":
+    car = Car ("blue", 1000)
+    print (car.i_color)
+    print (car.i_mileage)
+    print (car.c_mileage_units)
+    print (Car.c_mileage_units)

Chapter3/classes/carexample3.py

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+#carexample3.py
+class Car:
+    c_mileage_units = "Mi"
+    def __init__(self, color, miles):
+        self.i_color = color
+        self.i_mileage = miles
+
+if __name__ == "__main__":
+    car1 = Car ("blue", 1000)
+    car2 = Car("red", 2000)
+
+    print("using car1: " + car1.c_mileage_units)
+    print("using car2: " + car2.c_mileage_units)
+    print("using Class: " + Car.c_mileage_units)
+
+    car1.c_mileage_units = "km"
+
+    print("using car1: " + car1.c_mileage_units)
+    print("using car2: " + car2.c_mileage_units)
+    print("using Class: " + Car.c_mileage_units)
+
+    Car.c_mileage_units = "NP"
+    print("using car1: " + car1.c_mileage_units)
+    print("using car2: " + car2.c_mileage_units)
+    print("using Class: " + Car.c_mileage_units)

Chapter3/classes/carexample4.py

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+#carexampl4.py
+class Car:
+    c_mileage_units = "Mi"
+    def __init__(self, color, miles):
+        self.i_color = color
+        self.i_mileage = miles
+
+    def __str__(self):
+        return f"car with color {self.i_color} and mileage {self.i_mileage}"
+
+if __name__ == "__main__":
+    car1 = Car ("blue", 1000)
+    print (str(car1))
+    print(repr(car1))
+    print(dir(car1))

Chapter3/classes/carexample5.py

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+#carexample5.py
+class Car:
+    c_mileage_units = "Mi"
+    __max_speed = 200
+
+    def __init__(self, color, miles, model):
+        self.i_color = color
+        self.i_mileage = miles
+        self.__no_doors = 4
+        self._model = model
+
+    def __str__(self):
+        return f"car with color {self.i_color}, mileage {self.i_mileage}, model {self._model} and doors {self.__doors()}"
+
+    def __doors(self):
+        return self.__no_doors
+
+if __name__ == "__main__":
+    car = Car ("blue", 1000, "Camry")
+    print (car)
+
+    """These lines are only for illustration and not best practice"""
+    print(Car._Car__max_speed)
+    print (car._Car__doors())
+    print (car._model)         #possible but against the protected definition

Chapter3/classes/carexample6.py

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+#carexample6.py
+class Car:
+    __mileage_units = "Mi"
+    def __init__(self, col, mil):
+        self.__color = col
+        self.__mileage = mil
+
+    def __str__(self):
+        return f"car with color {self.get_color()} and mileage {self.get_mileage()}"
+
+    def get_color(self):
+        return self.__color
+
+    def get_mileage(self):
+        return self.__mileage
+
+    def set_mileage (self, new_mil):
+            self.__mileage = new_mil
+
+
+if __name__ == "__main__":
+    car = Car ("blue", 1000)
+
+    print (car)
+    print (car.get_color())
+    print(car.get_mileage())
+    car.set_mileage(2000)
+    print (car.get_color())
+    print(car.get_mileage())
+

Chapter3/classes/carexample7.py

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+#carexample7.py
+class Car:
+    __mileage_units = "Mi"
+    def __init__(self, col, mil):
+        self.__color = col
+        self.__mileage = mil
+
+    def __str__(self):
+        return f"car with color {self.color} and mileage {self.mileage}"
+
+    @property
+    def color(self):
+        return self.__color
+
+    @property
+    def mileage(self):
+        return self.__mileage
+
+    @mileage.setter
+    def mileage (self, new_mil):
+            self.__mileage = new_mil
+
+
+if __name__ == "__main__":
+    car = Car ("blue", 1000)
+
+    print (car)
+    print (car.color)
+    print(car.mileage)
+    car.mileage = 2000
+    print (car.color)
+    print(car.mileage)

Chapter3/classes/carwithInnerexample1.py

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+#carwithinnerexample1.py
+class Car:
+    """outer class"""
+    c_mileage_units = "Mi"
+    def __init__(self, color, miles, eng_size):
+        self.i_color = color
+        self.i_mileage = miles
+        self.i_engine = self.Engine(eng_size)
+
+    def __str__(self):
+        return f"car with color {self.i_color}, mileage {self.i_mileage} and engine of {self.i_engine}"
+
+    class Engine:
+        """inner class"""
+        def __init__(self, size):
+            self.i_size = size
+
+        def __str__(self):
+            return self.i_size
+
+
+if __name__ == "__main__":
+    car = Car ("blue", 1000, "2.5L")
+    print (car)
+    print (car.i_engine.i_size)

Chapter3/classes/methodsexample1.py

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+#methodsexample1.py
+class Car:
+    c_mileage_unit = "Mi"
+
+    def __init__(self, color, miles):
+        self.i_color = color
+        self.i_mileage = miles
+
+    def print_color (self):
+        print (f"Color of the car is {self.i_color}")
+
+    @classmethod
+    def print_units(cls):
+        print (f"mileage unit are {cls.c_mileage_unit}")
+        print(f"class name is {cls.__name__}")
+
+    @staticmethod
+    def print_hello():
+        print ("Hello from a static method")
+
+
+if __name__ == "__main__":
+    car = Car ("blue", 1000)
+    car.print_color()
+    car.print_units()
+    car.print_hello()
+
+    Car.print_color(car);
+    Car.print_units();
+    Car.print_hello()

Chapter3/classes/snippets.py

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+#snippet.py
+class Name:
+    def __init__(self):
+        self.first = "John"
+
+class Name:
+    #class attributes
+    c_name_length = 80
+
+    #constructor
+    def __init__(self, first, last):
+        self.i_first = first    #i_first is an instance attribute
+        self.i_last = last      #i_last is an instance attribute