Create_Class_v2.py

# Create a class with attributes
class Car1:
    max_speed = 300
    mileage = 20

# Create a class with instance attributes
class Car2:
    def __init__(self, max_speed, mileage):
        self.max_speed = max_speed
        self.mileage = mileage

m1 = Car1()
m2 = Car2(300, 20)

m1.max_speed
# 300
m2.max_speed
# 300

# Create a class with no attributes and methods
class Car3:
    pass

# Create a child class that will inherit all of the attributes and methods of the parent class
class Car:
    def __init__(self, brand, max_speed, mileage):
        self.brand, self.max_speed, self.mileage  = brand, max_speed, mileage

class Tesla(Car): # An empty class inheritated from Car
    pass
    
m4 = Tesla("Tesla", 360, 30)
print ("Car brand: {}, Maximum speed: {}, Mileage: {}.".format(m4.brand, m4.max_speed, m4.mileage))

isinstance(m4, Tesla) # True
isinstance(m4, Car) # True
# isinstance() is a built-in Python function that checks if an object is of a certain type (or a subclass).
# isinstance(object, Class) returns True or False.
a = 1
isinstance(a, int)
# True

# Create a class with attributes and method 
class Car:
    def __init__(self, brand, max_speed, mileage):
        self.brand = brand
        self.max_speed = max_speed
        self.mileage = mileage
    
    def seat_capacity(self, capacity):
        return "The seating capacity of a {} is {} passengers".format(self.brand, capacity)
m5 = Car("Audi", 350, 30)
m5.seat_capacity(5)
# 'The seating capacity of a Audi is 5 passengers'

# Create a child class that will inherit all of the attributes and methods (default value of capacity: 3) of the parent class
class MINI(Car):
    def seat_capacity(self, capacity=3):
        return super().seat_capacity(capacity=3) # super() access methods of the base class
m5 = MINI("MINI", 250, 15)
m5.seat_capacity()

# Instance variable vs class variable
class Car:
    def __init__(self, brand, max_speed, mileage, color = "White"):
        self.brand = brand
        self.max_speed = max_speed
        self.mileage = mileage
        self.color = color

class Tesla(Car):
    pass

m6 = Tesla("Tesla Model Y", 155, 330)
m6_2 = Tesla("Tesla Model S", 200, 405)
m6.color
m6_2.color
# Variables created in .__init__() are called instance variables. 
# # An instance variable’s value is specific to a particular instance of the class. 
# For example, all car objects have a name and a max_speed, but the name and max_speed variables’ values will vary depending on the car instance.

# Define a color attribute that must have the same value for every class instance
class Car:
    color = "White"
    def __init__(self, brand, max_speed, mileage):
        self.brand = brand
        self.max_speed = max_speed
        self.mileage = mileage

class Tesla(Car):
    pass

m7 = Tesla("Tesla Model Y", 155, 330)
m7.color
# The class variable is shared between all class instances. 
# We can define a class attribute by assigning a value to a variable name outside of .__init__().

# Create a Porsche child class that inherits from the Car class. 
# The default fare charge of any car is seating capacity * 100. 
# If Car is a Porsche instance, we need to add an extra 6% on full fare as a maintenance charge. 
# Hence, the total fare for a Porsche instance is final amount = total fare + 6% of the total fare.
class Car:
    color = "Black"
    def __init__(self, brand, max_speed, mileage, capacity):
        self.brand = brand
        self.max_speed = max_speed
        self.mileage = mileage
        self.capacity = capacity
    
    def fare(self):
        return self.capacity * 100

class Porsche(Car):
    def fare(self):
        return self.capacity * 100 * (1  + 0.06) 
    
m8 = Porsche("Porsche 911", 182, "18 mpg city", 2)
m8.fare()

# Another variant
class Porsche(Car):
    def fare(self):
        total_amount = super().fare()
        total_amount += total_amount * 6 / 100
        return total_amount
    
m8_2 = Porsche("Porsche 911", 182, "18 mpg city", 2)
m8_2.fare()

# Check type of a Porsche object
type(m8)   
# <class '__main__.Porsche'>

# Check if m8 is also an instance of the Car class
print(isinstance(m8, Car))
# True