What is method overloading in python

What is method overloading in Python?

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Methods in Python can be called with zero, one, or more parameters. This process of calling the same method in different ways is called method overloading. It is one of the important concepts in OOP. Two methods cannot have the same name in Python; hence method overloading is a feature that allows the same operator to have different meanings.

Overloading is a method or operator that can do different functionalities with the same name.

#Program to illustrate method overloading
class edpresso:
 
def Hello(self, name=None):
 
if name is not None:
 
print('Hello ' + name)
 
else:
 
print('Hello ')
 
# Create an instance
obj = edpresso()
 
# Call the method
obj.Hello()
 
# Call the method with a parameter
obj.Hello('Kadambini')

In the code above, we are able to call the method Hello in two different ways with the help of method overloading .

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Method overloading

Several ways to call a method (method overloading)

In Python you can define a method in such a way that there are multiple ways to call it.

Given a single method or function, we can specify the number of parameters ourself.

Depending on the function definition, it can be called with zero, one, two or more parameters.

This is known as method overloading. Not all programming languages support method overloading, but Python does.

Method overloading example

We create a class with one method sayHello(). The first parameter of this method is set to None, this gives us the option to call it with or without a parameter.

An object is created based on the class, and we call its method using zero and one parameter.

#!/usr/bin/env python

class Human:

def sayHello(self, name=None):

if name is not None:
print(‘Hello ‘ + name)
else:
print(‘Hello ‘)

# Create instance
obj = Human()

# Call the method
obj.sayHello()

# Call the method with a parameter
obj.sayHello(‘Guido’)

To clarify method overloading, we can now call the method sayHello() in two ways:

obj.sayHello()
obj.sayHello(‘Guido’)

We created a method that can be called with fewer arguments than it is defined to allow.

We are not limited to two variables, your method could have more variables which are optional.

If you are new to Python programming, I highly recommend this book.

So to clarify, if no argument is given for the second parameter, the second parameter will be set to None?

Yes, if no parameter is given it will be set to None. There is no limit to the number of parameters you pass.
You could have a method that accepts multiple parameters:

#!/usr/bin/env python

class Human:

def sayHello(self, name=None, age=None):

if name is not None:
print ‘Hello ‘ + name
else:
print ‘Hello ‘

if age is not None:
print ‘Age = ‘ + str(age)

# Create instance
obj = Human()

# Call the method
obj.sayHello()

# Call the method with a parameter
obj.sayHello(‘Guido’)

# Call with two parameters
obj.sayHello(‘Guido’,18)

What abou situation: we have no first argument, and have the second?

Hi Andrew, you could pass the first parameter as None. An alternative would be to pass an instance of a class (an object) to a method, which is what I recommend if you want to pass a lot of variables.

Can you have other variables in overloading besides none? Such as def sayHello(self, name=’Default User’): ?

This seems to work. Usually constant variables are defined in the local scope of the function, you could use it as default value for a parameter.

Thank you. It looks easier)

Hello, how can i do that?(last command)

#!/usr/bin/env python

class Human:

def sayHello(self, name=None, age=None):

if name is not None and age is None:
print (‘Hello ‘ + name)

elif age is not None and age is not None:
print (‘Hello ‘ + name + ‘ your are ‘ + age + ‘ years old !’)
else:
print (‘Hello ‘)

# Create instance
obj = Human()

# Call the method
obj.sayHello()

# Call the method with a parameter
obj.sayHello( ‘Ad’, ’23’)

obj.sayHello(, ’23’)

Try None for the first argument.

it didn’t work for me by writing none for the first arguement !!

def sayHello(self, name=None, age=None):
if name is not None and age is None:
print (‘Hello ‘ + name)
elif name is not None and age is not None:
print (‘Hello ‘ + name + ‘ your are ‘ + str(age) + ‘ years old !’)
else:
print (‘Hello ‘)

Dear Frank,
i want some help in packages. i have not found any article related to packages on this website. sorry i am posting my question in this method overloading section. I have made three packages named Data, Student and postgraduate. postgraduate is subpackage of student package. there are files : biodata.py and _init_.py in student and subjects.py and_init_.py in postgraduate respectively.
code in biodata.py:

class Student_Info:

def personal_info(self,name,age,roll_no):
print(«age is»,self.name)
print(«name is»,self.age)
print(«roll no is»,self.roll_no)
class Info:

def display(self):
print(«the subjects are»)
print(«OOP»)
print(«DBMS»)

in package Data there are two files _init_.py and test.py
i want to access the methods of student_info and info into Data package. i mean by running Data package i could see output of these methods here. for this purpose i have written this code in test.py

import student.postgraduate
import student

class Data_display:

def method(self):
print(«this will display data»)

obj=Student_Info()
obj.personal_info(«sadia»,12,»Reg_09″)
obj2=Info()
obj2.display()

i am getting error on object creation. (obj=Student_Info() and obj2=Info() . please tell me what i am doing wrong in this program.
thank you

Hi Sadia,you are missing some imports:

from biodata import Student_Info
from subject import Info

Presently an object of student_info is not given a name or age. We can set the object variables by using a constructor.
I’ve changed biodata.py (Student_Info) class:

class Student_Info:

name = «»
age = 0
roll_no = 0

def __init__(self,name,age,roll_no):
self.name = name
self.age = age
self.roll_no = roll_no

def personal_info(self):
print(«age is»,self.name)
print(«name is»,self.age)
print(«roll no is»,self.roll_no)
from biodata import Student_Info
from subject import Info

class Data_display:

def method(self):
print(«this will display data»)

obj=Student_Info(«sadia»,12,»Reg_09″)
obj.personal_info()

obj2=Info()
obj2.display()

try last function as following
obj.sayhello(age=23)

__author__ = ‘jatin’
try this i m getting output

class Human:
def sayHello(self, name=None, age=None):
if name is not None and age is None:
print (‘Hello ‘ + name)
elif age is not None and name is not None:
print (‘Hello ‘ + ‘ your are ‘ + age + ‘ years old !’)
else:
print (‘Hello ‘)

# Create instance
obj = Human()
# Call the method
obj.sayHello()
# Call the method with a parameter
obj.sayHello( ‘Ad’, ’23’)
obj.sayHello(age=23)

Just short notice about boolean condition. It could be shortened from the form:

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A Complete Guide To Method Overloading in Python (With examples)

Overloading is the ability of a function, method, or operator to work differently when you pass different parameters to the same. Method overloading or Function overloading in Python have commonly used terms. Some of the main advantages of overloading is that you can use one method in multiple ways, which helps you keep your code cleaner and removes complexity when working with a team.

What is Method Overloading?

In Object-Oriented Programming, Method Overloading is used in scenarios where, for a specific object, a particular method can be called in more than one way according to the project requirement.

Examples of Method Overloading in Python are discussed in detail later in the article.

What is Method Overriding?

Method Overriding in Python is similar to Method Overloading except for that method overriding occurs between a subclass and a superclass. It has the same parameters as to when the methods are called. Yet, they behave differently due to some of the functionality being overridden from the superclass.

Example of Method Overriding

print(‘I’m the first feature of class X’)

print(‘I’m the second feature of class X’)

print(‘I’m the modified first feature of class X in class Y’)

print(‘I’m a feature of class Y’)

I’m the modified first feature of class X in class Y

method1 was overridden by class Y.

Method Overloading in Python

The problem with method overloading in Python is that Python does not support it by default. However, there are workarounds to do the same.

The Problem

Let us consider the following code:

At first glance, the code looks good, but when you try to execute it with two arguments, Python will show you an error because in Python, when you have more than one method of the same name but a different number of arguments, only the latest defined method can be used.

There are two different ways we can overcome this problem of method overloading in Python.

1: Using the same methods differ according to the data type of the arguments

We can see an argument to know the data type, along with *args that allows passing a variable number of arguments to a method in Python. We can then use if statements to control how the method behaves according to the input.

This was the first workaround to implement method overloading in Python.

2: Using Multiple Dispatch Decorator (More efficient way)

Multiple Dispatch Decorator is less of a workaround and works exactly like it is supposed to. You can install it using pip3.

pip3 install multiple dispatches

from multiple dispatch import dispatch

@dispatch(int,int) # for 2 integer arguments

@dispatch(int,int,int) # for 3 integer arguments

@dispatch(float,float,float) # for float arguments

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When executing, the dispatcher makes a new object that stores different implementations of the method and decides the method to select depending on the type and number of arguments passed while calling the method. This way method of overloading in Python is more efficient.

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Conclusions

If you wish to enter the field of Data Science, Python is a good first step to take. To dive deep and study the topic further, you can check out advanced online certifications courses like the Executive Programme in Data Science by IIIT-Bangalore in association with upGrad . This program covers the important aspects of the subject and provides a lot of additional benefits like job assistance, 1:1 Mentorship, online support, live lectures, and optional additional modules for enthusiasts who want to upskill further.

Rohit Sharma

Rohit Sharma is the Program Director for the UpGrad-IIIT Bangalore, PG Diploma Data Analytics Program.

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Frequently Asked Questions (FAQs)

In Python, there are two kinds of functions: built-in functions and user-defined functions. print() and len() are examples of built-in functions. User-defined functions in python are functions that we can define ourselves to do a specific task more than once in a typical program. Method is just like a function except that methods belong to a class and can be called only on an object. (Syntax: obj.method())

Python and R are the two top languages used for Data Science. While what to use depends on several factors like the company you’re aiming for, the type of project, client requirements, etc., generally, if you are a beginner in programming, working in an engineering environment building large-scale applications, Python is a great choice. On the other hand, if you have prior programming experience and want to run data analysis tasks rapidly and visualise your data using beautiful graphics to make a better decision statistically, R is the way to go.

Everyone has their own learning pace. Although, for a beginner with no prior programming experience, it will take you close to 6-7 months to make your fundamentals strong. Post that, it again depends on how much you practice and the projects to work on. If you follow an online certification, you should be able to master it in around a year.

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