Purpose of polymorphism in Python - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Polymorphism Purpose

What is the main purpose of polymorphism in programming?

A To allow objects of different classes to be treated as objects of a common superclass

B To increase the speed of program execution by using multiple processors

C To store multiple values in a single variable

D To prevent any changes to the data once it is set

💡 Hint

Think about how different objects can share the same interface or method names.

Polymorphism allows different classes to be accessed through the same interface, enabling flexible and reusable code.

❓ Predict Output

intermediate

Output of Polymorphism Example

What is the output of this Python code demonstrating polymorphism?

Python

class Animal:
    def sound(self):
        return "Some sound"

class Dog(Animal):
    def sound(self):
        return "Bark"

class Cat(Animal):
    def sound(self):
        return "Meow"

animals = [Dog(), Cat(), Animal()]
for animal in animals:
    print(animal.sound())

A

Some sound
Some sound
Some sound

B

Bark
Bark
Bark

C

Bark
Meow
Some sound

D

Meow
Bark
Some sound

💡 Hint

Each subclass overrides the sound method.

The Dog and Cat classes override the sound method of Animal. When called, the method of the actual object type runs.

🔧 Debug

advanced

Identify the Polymorphism Error

What error will this code produce related to polymorphism?

Python

class Bird:
    def fly(self):
        print("Flying")

class Penguin(Bird):
    pass

p = Penguin()
p.fly()

A No error, prints 'Flying'

B TypeError: Cannot call fly on Penguin

C AttributeError: 'Penguin' object has no attribute 'fly'

D NameError: Bird is not defined

💡 Hint

Check if Penguin inherits the method from Bird.

Penguin inherits from Bird, so it has the fly method. Calling p.fly() prints 'Flying' without error.

📝 Syntax

advanced

Correct Polymorphic Method Syntax

Which option correctly defines a polymorphic method area in two classes?

Python

class Shape:
    def area(self):
        pass

class Square(Shape):
    def __init__(self, side):
        self.side = side

    # Define area method here

class Circle(Shape):
    def __init__(self, radius):
        self.radius = radius

    # Define area method here

A

Square: def area(self): return self.side + self.side
Circle: def area(self): return 3.14 * self.radius

B

Square: def area(): return side * side
Circle: def area(): return 3.14 * radius ** 2

C

Square: def area(self): return side * side
Circle: def area(self): return 3.14 * radius ** 2

D

Square: def area(self): return self.side * self.side
Circle: def area(self): return 3.14 * self.radius ** 2

💡 Hint

Remember to use self to access instance variables.

Methods must include self and use it to access instance variables. The formulas must be correct for area.

🚀 Application

expert

Polymorphism in Function Arguments

What will be the output of this code that uses polymorphism in function arguments?

Python

class Printer:
    def print_message(self):
        print("Generic message")

class EmailPrinter(Printer):
    def print_message(self):
        print("Email message")

class SMSPrinter(Printer):
    def print_message(self):
        print("SMS message")

def send_notification(printer: Printer):
    printer.print_message()

send_notification(EmailPrinter())
send_notification(SMSPrinter())
send_notification(Printer())

A

SMS message
Email message
Generic message

B

Email message
SMS message
Generic message

C

Email message
Email message
Email message

D

Generic message
Generic message
Generic message

💡 Hint

Each subclass overrides print_message. The function calls the method on the passed object.

The function send_notification calls print_message on the object passed. Polymorphism ensures the correct method runs based on the object's class.

Practice

1. What is the main purpose of polymorphism in Python programming?

easy

A. To allow one function or method to work in different ways depending on the object

B. To make the program run faster by using multiple processors

C. To store multiple values in a single variable

D. To create a new data type from existing types

Solution

1. Step 1: Understand the meaning of polymorphism

   Polymorphism means one action can behave differently depending on the object it is acting on.

2. Step 2: Match the purpose with the options

   To allow one function or method to work in different ways depending on the object correctly describes this behavior, while others describe unrelated concepts.

3. Final Answer:

   To allow one function or method to work in different ways depending on the object -> Option A

4. Quick Check:

   Polymorphism = One action, many behaviors [OK]

Hint: Polymorphism means same name, different actions [OK]

Common Mistakes:

• Confusing polymorphism with speed optimization
• Thinking polymorphism is about storing multiple values
• Mixing polymorphism with data type creation

2. Which of the following is the correct way to demonstrate polymorphism with methods in Python?

easy

A. Define multiple methods with different names in the same class

B. Define methods with the same name in different classes and call them on their objects

C. Use only one method in one class without overriding

D. Use global variables to change method behavior

Solution

1. Step 1: Recall how polymorphism works with methods

   Polymorphism allows methods with the same name to behave differently in different classes.

2. Step 2: Check which option matches this behavior

   Define methods with the same name in different classes and call them on their objects correctly describes defining same-named methods in different classes and calling them on their objects.

3. Final Answer:

   Define methods with the same name in different classes and call them on their objects -> Option B

4. Quick Check:

   Same method name, different classes = polymorphism [OK]

Hint: Same method name in different classes shows polymorphism [OK]

Common Mistakes:

• Thinking polymorphism means different method names
• Ignoring method overriding in subclasses
• Using global variables to control method behavior

3. What will be the output of the following code?

class Dog:
    def sound(self):
        return "Bark"

class Cat:
    def sound(self):
        return "Meow"

animals = [Dog(), Cat()]
for animal in animals:
    print(animal.sound())

medium

A. Meow
Bark

B. Bark
Bark

C. Error: sound method not found

D. Bark
Meow

Solution

1. Step 1: Understand the classes and their methods

   Dog and Cat classes both have a method named sound that returns different strings.

2. Step 2: Trace the loop calling sound on each object

   The loop calls sound() on Dog instance (returns "Bark") and Cat instance (returns "Meow"), printing each.

3. Final Answer:

   Bark Meow -> Option D

4. Quick Check:

   Different classes, same method name, different outputs [OK]

Hint: Same method name, different classes, different outputs [OK]

Common Mistakes:

• Assuming both calls return the same string
• Expecting a runtime error due to method name
• Mixing the order of outputs

4. Find the error in this code that tries to use polymorphism:

class Bird:
    def fly(self):
        print("Flying")

class Penguin(Bird):
    def fly(self):
        print("Cannot fly")

p = Penguin()
p.fly()

medium

A. No error; code correctly uses polymorphism

B. Penguin class must call super().fly() inside fly

C. Method fly must return a value

D. Penguin class should not override fly method

Solution

1. Step 1: Check method overriding in subclass

   Penguin overrides fly method to print "Cannot fly", which is valid polymorphism.

2. Step 2: Verify code execution

   Creating Penguin object and calling fly prints "Cannot fly" without error.

3. Final Answer:

   No error; code correctly uses polymorphism -> Option A

4. Quick Check:

   Overriding method in subclass is correct polymorphism [OK]

Hint: Overriding method in subclass is allowed [OK]

Common Mistakes:

• Thinking overriding is an error
• Expecting method must return a value
• Believing super() call is mandatory

5. You want to write a function that accepts any object and calls its draw() method, regardless of the object's class. Which concept does this best illustrate?

hard

A. Inheritance

B. Encapsulation

C. Polymorphism

D. Abstraction

Solution

1. Step 1: Understand the function requirement

   The function calls draw() on any object without knowing its class.

2. Step 2: Identify the concept allowing this behavior

   Polymorphism allows different objects to respond to the same method call appropriately.

3. Final Answer:

   Polymorphism -> Option C

4. Quick Check:

   Same method call, different objects = polymorphism [OK]

Hint: Calling same method on any object shows polymorphism [OK]

Common Mistakes:

• Confusing with inheritance which is about class hierarchy
• Mixing with encapsulation which hides data
• Thinking abstraction means calling any method