Class Properties in Python

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Class Properties in Python

Properties are variables that store data inside a class or its objects.

Each object created from a class can have its own set of properties.

Defining Properties in a Class

Most properties are defined inside the __init__() method.

These are called instance properties because they belong to individual objects.

Example: Create a Class with Properties

class Employee: def __init__(self, emp_id, salary): self.emp_id = emp_id self.salary = salary e1 = Employee(101, 45000) print(e1.emp_id) print(e1.salary)

Output:

101
45000

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Accessing Object Properties

You can access properties using dot notation:

object_name.property_name

Example: Access Properties

class Phone: def __init__(self, brand, price): self.brand = brand self.price = price p1 = Phone("Samsung", 30000) print(p1.brand) print(p1.price)

Output:

Samsung
30000

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Modifying Properties

Object properties can be updated after the object is created.

Example: Update a Property Value

class User: def __init__(self, name, points): self.name = name self.points = points u1 = User("Amit", 80) print(u1.points) u1.points = 95 print(u1.points)

Output:

80
95

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Deleting Properties

You can remove a property from an object using the del keyword.

Example: Delete a Property

class Player: def __init__(self, username, level): self.username = username self.level = level p1 = Player("Neo", 7) del p1.level print(p1.username) try: print(p1.level) except AttributeError as e: print(f"Error: {e}")

Output:

Neo
Error: 'Player' object has no attribute 'level'

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Class Properties vs Instance Properties

Python supports two types of properties:

Instance Properties

• Defined inside __init__()
• Unique to each object

Class Properties

• Defined directly inside the class
• Shared by all objects

Example: Class vs Instance Property

class Animal: category = "Mammal" # Class property def __init__(self, name): self.name = name # Instance property a1 = Animal("Dog") a2 = Animal("Cat") print(a1.name) print(a2.name) print(a1.category) print(a2.category)

Output:

Dog
Cat
Mammal
Mammal

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Modifying Class Properties

When a class property is modified, the change affects all objects created from that class.

Example: Update a Class Property

class Company: country = "India" def __init__(self, name): self.name = name c1 = Company("TechSoft") c2 = Company("InnoLabs") Company.country = "USA" print(c1.country) print(c2.country)

Output:

USA
USA

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Adding New Properties to Objects

Python allows you to add new properties to objects dynamically, even after creation.

Example: Add Properties at Runtime

class Customer: def __init__(self, name): self.name = name c1 = Customer("Rahul") c1.email = "rahul@example.com" c1.balance = 1200 print(c1.name) print(c1.email) print(c1.balance)

Output:

Rahul
rahul@example.com
1200

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