Python Class Properties

🐍 Python Class Properties

In Python, class properties (also called attributes) allow you to define and control access to data inside a class.
Properties provide a clean interface for getting, setting, and deleting attribute values.

1️⃣ Basic Class Properties

self.name and self.age are instance properties.
Each object can have different values.

2️⃣ Class Variables vs Instance Variables

class Laptop:
brand = "Dell" # class property (shared by all objects)def __init__(self, ram):
self.ram = ram # instance property (unique per object)

l1 = Laptop("8GB")
l2 = Laptop("16GB")

print(l1.brand, l1.ram) # Dell 8GB
print(l2.brand, l2.ram) # Dell 16GB

class Laptop:

brand = "Dell" # class property (shared by all objects)def __init__(self, ram):

self.ram = ram # instance property (unique per object)

l1 = Laptop("8GB")

l2 = Laptop("16GB")

print(l1.brand, l1.ram) # Dell 8GB

print(l2.brand, l2.ram) # Dell 16GB

Class Property → shared across all instances
Instance Property → unique to each object

3️⃣ Using `@property` Decorator

The @property decorator allows you to access methods like attributes.
This is useful for computed properties.

class Circle:
def __init__(self, radius):
self._radius = radius # private variable by convention @property
def radius(self):
return self._radius

@property
def area(self):
return 3.14 * self._radius ** 2

c = Circle(5)
print(c.radius) # 5
print(c.area) # 78.5

class Circle:

def __init__(self, radius):

self._radius = radius # private variable by convention @property

def radius(self):

return self._radius

@property

def area(self):

return 3.14 * self._radius ** 2

c = Circle(5)

print(c.radius) # 5

print(c.area) # 78.5

Access c.area without parentheses
Makes your class interface clean and safe

4️⃣ Setter Method with `@property`

class Circle:
def __init__(self, radius):
self._radius = radius @property
def radius(self):
return self._radius

@radius.setter
def radius(self, value):
if value > 0:
self._radius = value
else:
print("Radius must be positive!")

c = Circle(5)
c.radius = 10
print(c.radius) # 10
c.radius = -3 # Radius must be positive!

class Circle:

def __init__(self, radius):

self._radius = radius @property

def radius(self):

return self._radius

@radius.setter

def radius(self, value):

if value > 0:

self._radius = value

else:

print("Radius must be positive!")

c = Circle(5)

c.radius = 10

print(c.radius) # 10

c.radius = -3 # Radius must be positive!

5️⃣ Deleter Method

class Person:
def __init__(self, name):
self._name = name @property
def name(self):
return self._name

@name.deleter
def name(self):
print("Deleting name...")
del self._name

p = Person("Vipul")
del p.name # Deleting name...

class Person:

def __init__(self, name):

self._name = name @property

def name(self):

return self._name

@name.deleter

def name(self):

print("Deleting name...")

del self._name

p = Person("Vipul")

del p.name # Deleting name...

6️⃣ Summary Table

Property Type	Usage
Instance Property	Unique per object (`self.var`)
Class Property	Shared by all objects (`Class.var`)
`@property`	Getter method, accessed like attribute
`@setter`	Update value safely
`@deleter`	Delete value safely

7️⃣ Example: Real-life Class with Properties

class Employee:
def __init__(self, name, salary):
self._name = name
self._salary = salary @property
def salary(self):
return self._salary

@salary.setter
def salary(self, value):
if value >= 0:
self._salary = value
else:
print("Salary cannot be negative!")

e = Employee("Raj", 50000)
print(e.salary) # 50000
e.salary = 60000
print(e.salary) # 60000
e.salary = -100 # Salary cannot be negative!

class Employee:

def __init__(self, name, salary):

self._name = name

self._salary = salary @property

def salary(self):

return self._salary

@salary.setter

def salary(self, value):

if value >= 0:

self._salary = value

else:

print("Salary cannot be negative!")

e = Employee("Raj", 50000)

print(e.salary) # 50000

e.salary = 60000

print(e.salary) # 60000

e.salary = -100 # Salary cannot be negative!

💡 Benefits of Class Properties

Protect data (encapsulation)
Control how attributes are accessed or modified
Clean & readable interface

Python Class Properties