Teaching Kids Programming – Introduction to Object Oriented Programming


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Object Oriented Programming (OOP) is an important programming design paradigm. We model data in classes and objects. Class is the object template where object is the instance of a Class. In this tutorial, we are going to look at using Python to create a Class Person, and a Class Car. And then, we are going to create two Persons: Eric and Ryan, also a car object Audi.

We can invoke the methods on objects using the dot operator. We use the __init__ to define a constructor which is used when creating/initialising the object. The first parameter needs to be self so that we know it belongs to the object.

We can use self.name in a constructor to declare the attributes of a class/object. We use function isinstance(a, b) to check if Object a is an instance of Class b.

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class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age
           
    def sayHello(self, msg):
        print(self.name + " says: " + msg)
        
    def howOld(self):
        print(self.name + " is " + str(self.age))
            
class Car:
    def __init__(self, brand, speed):
        self.brand = brand
        self.speed = speed
        
    def speed(self):
        return self.speed
            
Eric = Person("Eric", 8)
Ryan = Person("Ryan", 6)
 
Eric.sayHello("Hello")
Eric.howOld()
 
Ryan.sayHello("Hello")
Ryan.howOld()
 
Audi = Car("Audi", 100)
 
print(isinstance(Eric, Person))
print(isinstance(Audi, Person))
class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age
           
    def sayHello(self, msg):
        print(self.name + " says: " + msg)
        
    def howOld(self):
        print(self.name + " is " + str(self.age))
            
class Car:
    def __init__(self, brand, speed):
        self.brand = brand
        self.speed = speed
        
    def speed(self):
        return self.speed
            
Eric = Person("Eric", 8)
Ryan = Person("Ryan", 6)

Eric.sayHello("Hello")
Eric.howOld()

Ryan.sayHello("Hello")
Ryan.howOld()

Audi = Car("Audi", 100)

print(isinstance(Eric, Person))
print(isinstance(Audi, Person))

This prints the following:

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Eric says: Hello
Eric is 8
Ryan says: Hello
Ryan is 6
True
False
Eric says: Hello
Eric is 8
Ryan says: Hello
Ryan is 6
True
False

–EOF (The Ultimate Computing & Technology Blog) —

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