Introduction to Attributes and Methods

Attributes and methods define the characteristics and behavior of objects in Object-Oriented Programming (OOP). Attributes store data, while methods perform actions.

In this lesson, you’ll learn how to define and use attributes and methods effectively in Python classes.

What Are Attributes?

Attributes are variables that belong to a class or an object. They are defined inside the class and describe the properties of an object:

# Defining attributes in a class
class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age

person1 = Person("Alice", 30)
print(person1.name, person1.age)

Instance Attributes

Instance attributes are specific to an object and are defined using the self keyword:

# Instance attributes in a class
class Car:
    def __init__(self, brand, model):
        self.brand = brand
        self.model = model

car1 = Car("Toyota", "Corolla")
print(car1.brand, car1.model)

What Are Methods?

Methods are functions defined inside a class. They define the actions that objects can perform:

# Defining a method in a class
class Person:
    def greet(self):
        print("Hello!")

person1 = Person()
person1.greet()

Instance Methods

Instance methods operate on instance attributes and require the self parameter:

# Instance methods in a class
class Person:
    def __init__(self, name):
        self.name = name

    def greet(self):
        print(f"Hello, {self.name}!")

person1 = Person("Alice")
person1.greet()

Using Parameters in Methods

Methods can accept parameters to customize their behavior:

# Methods with parameters
class Calculator:
    def add(self, a, b):
        return a + b

calc = Calculator()
print(calc.add(3, 5))

Updating Attributes

You can update attributes using methods:

# Updating attributes using a method
class Person:
    def __init__(self, name):
        self.name = name

    def update_name(self, new_name):
        self.name = new_name

person = Person("Alice")
person.update_name("Bob")
print(person.name)

Common Mistakes with Attributes and Methods

Here are some mistakes to avoid:

• Forgetting to use self in method definitions.
• Accessing undefined attributes.
• Not initializing attributes properly in the constructor.

What Did We Learn?

In this lesson, you learned:

• What attributes and methods are in Python classes.
• How to define and use attributes and methods.
• How to customize methods with parameters and update attributes.

Great job! Let’s move to the next topic.