Fundamental Differences Between Python Functions and Object Methods

In Python, both functions and object methods are used to organize and reuse code, but they have different purposes. To understand which is more fundamental requires understanding how each one works and their roles in Python programming.

A function in Python is a block of reusable code that performs a specific task. A method is a function that is associated with an object, meaning it belongs to a class or an instance. While both functions and methods can be used to perform operations, functions are more fundamental in the Python language.

Why Functions Are More Fundamental in Python

Functions are considered more fundamental than object methods in Python because -

• Functions are the building blocks: Python itself is built around the concept of functions. Even methods are implemented using functions behind the scenes.
• Functions exist outside classes: Functions can be defined and used independently of any class or object. Methods, on the other hand, are tied to objects.
• Methods are special types of functions: In Python, a method is a function that is defined inside a class and takes the instance (usually named self) as its first argument.

What Are Functions in Python?

Functions are defined using the def keyword and are used to execute a set of statements. They can be called independently without needing an object.

Example

The following is a simple example of a function that adds two numbers -

# A simple function
def add(a, b):
   return a + b

result = add(4, 5)
print(result)

The output of the above code is -

9

What Are Object-Methods in Python?

Object methods are functions defined inside a class. They are called on instances of the class and can access or modify the object's internal state using self.

Example

In the following example, greet is a method because it is defined within a class and operates on the instance.

class Person:
   def __init__(self, name):
      self.name = name

   def greet(self):
      return "Hello " + self.name

p = Person("Rohan")
print(p.greet())

The output will be -

Hello Rohan

Methods Are Functions Inside Classes

In Python, methods are technically functions defined inside a class. When you access a method from an instance, Python automatically passes the instance as the first argument (usually called self).

Example

The method below is internally just a function that takes self as the first parameter -

class Sample:
   def show(self):
      print("This is a method")

# Calling it from the object
obj = Sample()
obj.show()

The output of this method call is -

This is a method

Using Functions vs Using Methods

You can use functions when -

• You need a reusable block of code that is not tied to any object.
• Your logic is general-purpose and doesn't depend on object state.

You can use methods when -

• You are working with classes and want behavior attached to objects.
• You need to manipulate or access internal object data (using self).