Python self Parameter
The self Parameter
The self parameter is a reference to the current instance of the class.
It is used to access properties and methods that belong to the class.
Example
Use self to access class properties:
class Person:
def __init__(self, name, age):
self.name = name
self.age = age
def greet(self):
print("Hello, my name is " + self.name)
p1 = Person("Emil", 25)
p1.greet()
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Note: The self parameter must be the first parameter of any method in the class.
Why Use self?
Without self, Python would not know which object's properties you want to access:
Example
The self parameter links the method to the specific object:
class Person:
def __init__(self, name):
self.name = name
def printname(self):
print(self.name)
p1 = Person("Tobias")
p2 = Person("Linus")
p1.printname()
p2.printname()
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self Does Not Have to Be Named "self"
It does not have to be named self, you can call it whatever you like, but it has to be the first parameter of any method in the class:
Example
Use the words myobject and abc instead of self:
class Person:
def __init__(myobject, name, age):
myobject.name = name
myobject.age = age
def greet(abc):
print("Hello, my name is " + abc.name)
p1 = Person("Emil", 36)
p1.greet()
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Note: While you can use a different name, it is strongly recommended to use self as it is the convention in Python and makes your code more readable to others.
Accessing Properties with self
You can access any property of the class using self:
Example
Access multiple properties using self:
class Car:
def __init__(self, brand, model, year):
self.brand = brand
self.model = model
self.year = year
def display_info(self):
print(f"{self.year} {self.brand} {self.model}")
car1 = Car("Toyota", "Corolla", 2020)
car1.display_info()
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Calling Methods with self
You can also call other methods within the class using self:
Example
Call one method from another method using self:
class Person:
def __init__(self, name):
self.name = name
def greet(self):
return "Hello, " + self.name
def welcome(self):
message = self.greet()
print(message + "! Welcome to our website.")
p1 = Person("Tobias")
p1.welcome()
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