Class Properties
Properties are variables that belong to a class. They store data for each object created from the class.
Example
class Person:
def __init__(self, name, age):
self.name = name
self.age = age
p1 = Person("Emil", 36)
print(p1.name)
print(p1.age)
Access Properties
You can access object properties using dot notation:
Example
class Car:
def __init__(self, brand, model):
self.brand = brand
self.model = model
car1 = Car("Toyota", "Corolla")
print(car1.brand)
print(car1.model)
Modify Properties
You can modify the value of properties on objects:
Example
class Person:
def __init__(self, name, age):
self.name = name
self.age = age
p1 = Person("Tobias", 25)
print(p1.age)
p1.age = 26
print(p1.age)
Delete Properties
You can delete properties from objects using the del keyword:
Example
class Person:
def __init__(self, name, age):
self.name = name
self.age = age
p1 = Person("Linus", 30)
del p1.age
print(p1.name) # This works
# print(p1.age) # This would cause an error
Class Properties vs Object Properties
Properties defined inside __init__() belong to each object (instance properties).
Properties defined outside methods belong to the class itself (class properties) and are shared by all objects:
Example
class Person:
species = "Human" # Class property
def __init__(self, name):
self.name = name # Instance property
p1 = Person("Emil")
p2 = Person("Tobias")
print(p1.name)
print(p2.name)
print(p1.species)
print(p2.species)
Modifying Class Properties
When you modify a class property, it affects all objects:
Example
class Person:
lastname = ""
def __init__(self, name):
self.name = name
p1 = Person("Linus")
p2 = Person("Emil")
Person.lastname = "Refsnes"
print(p1.lastname)
print(p2.lastname)
Add New Properties
You can add new properties to existing objects:
Example
class Person:
def __init__(self, name):
self.name = name
p1 = Person("Tobias")
p1.age = 25
p1.city = "Oslo"
print(p1.name)
print(p1.age)
print(p1.city)
Note: Adding properties this way only adds them to that specific object, not to all objects of the class.