16. Python Class Inheritance with Examples (Video in Khmer)

Hello friend! 👋 Inheritance let one class use code from another class. The old class is called the parent. The new class is called the child.

In this post, I show you simple class and inheritance examples. 🐍

🔎 Useful Built-in Functions

Python has built-in functions to check an object and its class.

class Student:
    pass

student = Student()

print(type(student).__name__)   # Student
print(isinstance(student, Student))  # True

type() show the object's class. isinstance() check if an object belongs to a class.

🎥 Video: Built-in Functions for Class in Python (Khmer)

🎓 Student Class with Score

Use __init__ to set data when you make an object.

class Student:
    def __init__(self, name, score):
        self.name = name
        self.score = score

    def show_score(self):
        print(self.name, "score:", self.score)

student = Student("Dara", 95)
student.show_score()     # Dara score: 95

name and score are attributes. show_score() is a method.

🎥 Video: Student Class with Score Example (Khmer)

🧬 Make a Child Class

Put the parent class name in brackets to inherit its attributes and methods.

class Person:
    def __init__(self, name):
        self.name = name

    def say_hello(self):
        print("Hello, I am", self.name)

class Student(Person):
    def study(self):
        print(self.name, "is studying")

student = Student("Dara")
student.say_hello()      # Hello, I am Dara
student.study()          # Dara is studying

Student get the name attribute and say_hello() method from Person.

🎥 Video: How to Use Inheritance in Python (Khmer)

👤 Use `super()` with a Parent Class

Use super() to call the parent class setup code.

class Person:
    def __init__(self, name):
        self.name = name

class Student(Person):
    def __init__(self, name, school):
        super().__init__(name)
        self.school = school

student = Student("Dara", "Green School")
print(student.name)      # Dara
print(student.school)    # Green School

super().__init__(name) set the name from the parent class.

🎥 Video: More Inheritance with Person Class (Khmer)

❌ Common Error

Child class can use the parent setup only if you call it.

class Person:
    def __init__(self, name):
        self.name = name

class Student(Person):
    def __init__(self, name, school):
        super().__init__(name)
        self.school = school

If you make Student.__init__(), remember to call super().__init__(name) when you need the parent's data.

💡 Tips

A parent class has shared code. A child class inherits that code.
Use clear names, like Person and Student.
Use inheritance when classes have something in common.
Use super() to call a parent method or setup.
Use isinstance() to check an object's class.
Keep class code indented.

❓ Any Question?

Tell us in comment below! 👇

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