100 Days Of Python - Day 17
Day 17
Creating Classes
- Classes are blueprints for creating new objects.
- If the class name is has more than one word, it is written in
PascalCase
. - The syntax for creating a class is:
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class ClassName:
- If a class has no methods, it can be created with the
pass
keyword. This is useful when you want to create a class but donβt want to add any methods to it yet.
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class ClassName:
pass
Creating Objects
- Objects are instances of a class.
- If the object name is has more than one word, it is written in
snake_case
. - The syntax for creating an object is:
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object_name = ClassName()
Adding Attributes to Objects
- Attributes are variables that belong to an object.
- Attributes are added to an object using the dot notation.
- The syntax for adding an attribute to an object is:
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object_name.attribute_name = value
# Example
car.color = "red"
Adding Attributes to Classes
- Attributes can be added to a class using the
__init__()
method. - The
__init__()
method is called when an object is created. - It is also called the constructor method.
- The
__init__()
method is used to initialize the attributes of an object.
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class ClassName:
def __init__(self, attribute1, attribute2):
self.attribute1 = attribute1
self.attribute2 = attribute2
# Example
class Car:
def __init__(self, color, mileage):
self.color = color
self.mileage = mileage
car = Car("blue", 20000)
print(car.color)
print(car.mileage)
# Output:
# blue
# 20000
- The
self
keyword refers to the current object.
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class User:
def __init__(self, user_id, username):
self.id = user_id
self.username = username
user_1 = User("001", "Aretas")
print(user_1.id)
print(user_1.username)
# Output:
# 001
# Aretas
- defaulf values can be set for attributes in the
__init__()
method.
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class User:
def __init__(self, user_id, username, email):
self.id = user_id
self.username = username
self.email = email
self.followers = 0
self.following = 0
Adding Methods to Classes
- Methods are functions that belong to a class.
- Methods are added to a class using the dot notation.
- The syntax for adding a method to a class is:
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class ClassName:
def method_name(self):
# code goes here
# Example
class Car:
def __init__(self, color, mileage):
self.color = color
self.mileage = mileage
def drive(self, miles):
self.mileage += miles
car = Car("blue", 20000)
print(car.mileage)
car.drive(100)
print(car.mileage)
# Output:
# 20000
# 20100
- The
self
keyword refers to the current object.
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class User:
def __init__(self, user_id, username, email):
self.id = user_id
self.username = username
self.email = email
self.followers = 0
self.following = 0
def follow(self, user):
user.followers += 1
self.following += 1
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