Python Polymorphism: A Complete Tutorial with Examples
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Polymorphism is one of the core concepts of Object-Oriented Programming (OOP). It allows objects of different classes to be treated as objects of a common superclass. This means you can write code that works on the "interface" rather than the actual "implementation."
In this tutorial, you'll learn:
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What polymorphism is
-
How Python implements polymorphism
-
Real-world use cases
-
Tips and common pitfalls
-
A complete example at the end
✅ What is Polymorphism?
Polymorphism means "many forms." In Python, it refers to the ability of different objects to respond to the same method in different ways.
This allows functions, methods, or operators to process objects differently depending on their data type or class.
Types of Polymorphism in Python
Python supports two types of polymorphism:
-
Duck Typing (Dynamic Typing)
-
Method Overriding (Runtime Polymorphism)
Let’s understand both step by step.
1️⃣ Duck Typing (Informal Polymorphism)
Python follows "duck typing" — If it looks like a duck and quacks like a duck, it’s a duck.
You don’t care about the object’s type; you care whether it supports the desired behavior.
Example:
class Dog:
def speak(self):
return "Woof!"
class Cat:
def speak(self):
return "Meow!"
def animal_sound(animal):
print(animal.speak())
# Using different objects with the same interface
dog = Dog()
cat = Cat()
animal_sound(dog) # Output: Woof!
animal_sound(cat) # Output: Meow!
Here, both Dog and Cat have a speak() method, and we can pass either into animal_sound() — that's duck typing!
2️⃣ Method Overriding (Runtime Polymorphism)
When a subclass provides a specific implementation of a method defined in its superclass, it is method overriding.
Example:
class Animal:
def move(self):
print("The animal moves.")
class Bird(Animal):
def move(self):
print("The bird flies.")
class Fish(Animal):
def move(self):
print("The fish swims.")
def move_animal(animal):
animal.move()
# Different outputs based on object type
move_animal(Animal()) # Output: The animal moves.
move_animal(Bird()) # Output: The bird flies.
move_animal(Fish()) # Output: The fish swims.
Here, each subclass overrides the move() method in its own way — classic runtime polymorphism.
Operator Overloading (Bonus: Compile-time Polymorphism)
Although Python does not support traditional function overloading, it does support operator overloading.
Example:
print(10 + 5) # Output: 15 (int addition)
print("Hello " + "World") # Output: Hello World (string concatenation)
The + operator behaves differently based on the data type — a form of polymorphism!
Complete Code Example
Let’s put it all together with a practical example:
class Employee:
def work(self):
raise NotImplementedError("Subclasses must implement this method")
class Developer(Employee):
def work(self):
return "Writes code."
class Designer(Employee):
def work(self):
return "Designs user interfaces."
class Manager(Employee):
def work(self):
return "Manages team."
def perform_work(employee: Employee):
print(f"{employee.__class__.__name__}: {employee.work()}")
# Create a list of employees
team = [Developer(), Designer(), Manager()]
for member in team:
perform_work(member)
Output:
Developer: Writes code.
Designer: Designs user interfaces.
Manager: Manages team.
This is an example of polymorphism where each object behaves differently even though the interface (work) is the same.
Tips for Using Polymorphism in Python
-
Use abstract base classes to define expected interfaces using the
abcmodule. -
Prefer duck typing for flexible and concise code.
-
Use polymorphism to reduce
if-elseblocks that depend on object types. -
Document your methods well if relying on duck typing, since there's no type enforcement.
⚠️ Common Pitfalls
| Pitfall | Explanation |
|---|---|
❌ Relying too heavily on type() or isinstance() |
This defeats the purpose of polymorphism and makes your code rigid. |
| ❌ Forgetting to override base class methods | If you forget to override a method, Python won’t raise an error unless the method is actually called. |
| ❌ Missing default implementations | Always provide base class stubs (with raise NotImplementedError) for methods meant to be overridden. |
| ❌ Expecting compile-time polymorphism | Python does not support method overloading by default; last method defined with the same name wins. |
✅ Summary
| Concept | Description |
|---|---|
| Polymorphism | One interface, many implementations |
| Duck Typing | Behavior-based polymorphism without inheritance |
| Method Overriding | Subclass defines its own version of a method |
| Operator Overloading | Same operator, different behaviors depending on operand types |
Polymorphism in Python helps you write cleaner, more maintainable, and extensible code. Mastering it will make your object-oriented programs more elegant and powerful.
Tips and Tricks
What is pass in Python?
Python | Pass Statement
The pass statement is used as a placeholder for future code. It represents a null operation in Python. It is generally used for the purpose of filling up empty blocks of code which may execute during runtime but has yet to be written.
def myfunction():
pass
How can you generate random numbers?
Python | Generate random numbers
Python provides a module called random using which we can generate random numbers. e.g: print(random.random())
We have to import a random module and call the random() method as shown below:
import random
print(random.random())
The random() method generates float values lying between 0 and 1 randomly.
To generate customized random numbers between specified ranges, we can use the randrange() method
Syntax: randrange(beginning, end, step)
import random
print(random.randrange(5,100,2))
What is lambda in Python?
Python | Lambda function
A lambda function is a small anonymous function. This function can have any number of parameters but, can have just one statement.
Syntex:
lambda arguments : expression
a = lambda x,y : x+y
print(a(5, 6))
It also provides a nice way to write closures. With that power, you can do things like this.
def adder(x):
return lambda y: x + y
add5 = adder(5)
add5(1) #6
As you can see from the snippet of Python, the function adder takes in an argument x and returns an anonymous function, or lambda, that takes another argument y. That anonymous function allows you to create functions from functions. This is a simple example, but it should convey the power lambdas and closures have.
What is swapcase() function in the Python?
Python | swapcase() Function
It is a string's function that converts all uppercase characters into lowercase and vice versa. It automatically ignores all the non-alphabetic characters.
string = "IT IS IN LOWERCASE."
print(string.swapcase())
How to remove whitespaces from a string in Python?
Python | strip() Function | Remove whitespaces from a string
To remove the whitespaces and trailing spaces from the string, Python provides a strip([str]) built-in function. This function returns a copy of the string after removing whitespaces if present. Otherwise returns the original string.
string = " Python "
print(string.strip())
What is the usage of enumerate() function in Python?
Python | enumerate() Function
The enumerate() function is used to iterate through the sequence and retrieve the index position and its corresponding value at the same time.
lst = ["A","B","C"]
print (list(enumerate(lst)))
#[(0, 'A'), (1, 'B'), (2, 'C')]
Can you explain the filter(), map(), and reduce() functions?
Python | filter(), map(), and reduce() Functions
- filter() function accepts two arguments, a function and an iterable, where each element of the iterable is filtered through the function to test if the item is accepted or not.
>>> set(filter(lambda x:x>4, range(7))) # {5, 6}
-
map() function calls the specified function for each item of an iterable and returns a list of result
>>> set(map(lambda x:x**3, range(7))) # {0, 1, 64, 8, 216, 27, 125}
-
reduce() function reduces a sequence pair-wise, repeatedly until we arrive at a single value..
>>> reduce(lambda x,y:y-x, [1,2,3,4,5]) # 3Let’s understand this:
2-1=1
3-1=2
4-2=2
5-2=3Hence, 3.
What is a namedtuple?
Python | namedtuple
A namedtuple will let us access a tuple’s elements using a name/label. We use the function namedtuple() for this, and import it from collections.
>>> from collections import namedtuple
#format
>>> result=namedtuple('result','Physics Chemistry Maths')
#declaring the tuple
>>> Chris=result(Physics=86,Chemistry=92,Maths=80)
>>> Chris.Chemistry
# 92
Write a code to add the values of same keys in two different dictionaries and return a new dictionary.
We can use the Counter method from the collections module
from collections import Counter
dict1 = {'a': 5, 'b': 3, 'c': 2}
dict2 = {'a': 2, 'b': 4, 'c': 3}
new_dict = Counter(dict1) + Counter(dict2)
print(new_dict)
# Print: Counter({'a': 7, 'b': 7, 'c': 5})
Python In-place swapping of two numbers
Python | In-place swapping of two numbers
>>> a, b = 10, 20
>>> print(a, b)
10 20
>>> a, b = b, a
>>> print(a, b)
20 10
Reversing a String in Python
Python | Reversing a String
>>> x = 'PythonWorld'
>>> print(x[: : -1])
dlroWnohtyP
Python join all items of a list to convert into a single string
Python | Join all items of a list to convert into a single string
>>> x = ["Python", "Online", "Training"]
>>> print(" ".join(x))
Python Online Training
python return multiple values from functions
Python | Return multiple values from functions
>>> def A():
return 2, 3, 4
>>> a, b, c = A()
>>> print(a, b, c)
2 3 4
Python Print String N times
Python | Print String N times
>>> s = 'Python'
>>> n = 5
>>> print(s * n)
PythonPythonPythonPythonPython
Python check the memory usage of an object
Python | Check the memory usage of an object
>>> import sys
>>> x = 100
>>> print(sys.getsizeof(x))
28
