Objects and Classes

• every object has a type, an internal data representation (a blueprint), a set of procedures for interacting with the object (method)
• An object is an instance of a particular type -e.g Type 1: Object 1, Object 2,...

Objects

1/ Types:

• using type() to find the type of an object

type(1)

int

type('kevin')

str

2/ Methods:

• for example: .sort(), .append(), .add()

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Classes

1/ Defining classes

• Class includes both Data attributes & Methods
• You can create classes, for examples:

1.1/ Class Car

-> Data attributes: brand, color

class Car: # define your class

    def __init__(self, brand, color): # self is self parameter
        # brand and color are parameters
        self.brand = brand
        self.color = color
# those are data attributes used to initialize each instance of the class

2/ Create an instance of a Class: Car

class Car(object): #(object) is optional, in Python 2 we don't need (object)
    def __init__(self, brand, color): 
        self.brand = brand
        self.color = color
    def drive(self):
        print(f"The {self.color} {self.brand} is driving")

VinFast = Car('VinFast', 'red') 

VinFast.drive()

The red VinFast is driving

# NO __init__
class ToanTinTCTA:
    pass
    # this class is completely empty, no automatically assign a value or anything

# So now, if we want to create 2 individuals:
person1 = ToanTinTCTA()
person2 = ToanTinTCTA()
# U have to manually assign values to them, cuz its not automatic
person1.name = "Hong Phuc"
person1.username = "kevinph4n"

person2.name = "Hung Dan"
person2.username = "hungdan"

print(person1.name)

Hong Phuc

# WITH __init__
class ToanTinTCTA:
    def __init__(self, name, username):
        self.name = name
        self.username = username

person1 = ToanTinTCTA("Hong Phuc", "kevinph4n")
person2 = ToanTinTCTA("Hung Dan", "hungdan")

print(person1.name)

Hong Phuc

More examples

# Class
class WorldCup:
    pass

# Object
class WorldCup:
    pass
Messi = WorldCup()

# Variables bound to an object
class WorldCup_0:
    def __init__(self, full_name, won_the_wc, has_a_wife):
        self.full_name = full_name
        self.won_the_wc = won_the_wc
        self.has_a_wife = has_a_wife
messi = WorldCup_0("Lionel Messi", "Yes", "1 Wife")
print(messi.full_name)
print(messi.won_the_wc)
print(messi.has_a_wife)

Lionel Messi Yes 1 Wife

class WorldCup_1:
    def trash_talk(self):# Method
        print("I have money!")

messi = Fighter()
messi.trash_talk()

I'm the best!

# Inheritance: Child class inherits from parent class

class Athlete:
    pass

class Fighter(Athlete):# Inheritance 
    pass

# Example using inheritance 

class WorldCup_2:

  def height(self, height):
      # Maps height to height class
      return "Short"  

# Footballer class inherits from WorldCup_2
class Footballer(WorldCup_2):

  def __init__(self, name):
    self.name = name
  
  def print_name(self):
    print(self.name)

footballer = Footballer("Messi")  
print(footballer.height(160)) 
footballer.print_name()

Short Messi

class student:
    def __init__ (self, name, age, GPA):
        self.GPA = GPA
        self.name = name
        self.age = age

HungDan = student("Hung Dan", 21, 4.0)
HongPhuc = student("Hong Phuc", 18, 4.0)

print("HongPhuc's age: ", HongPhuc.age)
print("HungDan's GPA: ", HungDan.GPA)

HongPhuc's age: 18 HungDan's GPA: 4.0