Procedural vs object-oriented approach in Python - Hands-On Comparison

Procedural vs Object-Oriented Approach in Python

📖 Scenario: You are building a simple program to manage a list of books in a library. Each book has a title and an author. You will first create the program using a procedural approach, then improve it using an object-oriented approach.

🎯 Goal: Build a program that stores book information and prints each book's details. First, use a procedural style with dictionaries and functions. Then, use an object-oriented style with a class and methods.

📋 What You'll Learn

Create a list of dictionaries to store books with exact titles and authors

Create a variable to count the number of books

Use a for loop to print each book's title and author

Define a Book class with title and author attributes

Create Book objects and store them in a list

Use a for loop to print each Book object's details using a method

💡 Why This Matters

🌍 Real World

Managing collections of items like books, movies, or products is common in software. Procedural code works for simple tasks, but object-oriented code helps organize complex data and behavior.

💼 Career

Understanding both procedural and object-oriented programming is important for software development jobs. Object-oriented programming is widely used in real-world applications for better code organization and reuse.

1

Create a list of books using dictionaries

Create a list called books with these exact dictionaries: {'title': '1984', 'author': 'George Orwell'}, {'title': 'To Kill a Mockingbird', 'author': 'Harper Lee'}, and {'title': 'The Great Gatsby', 'author': 'F. Scott Fitzgerald'}.

Python

# Create the list of books with dictionaries
# Your code here

Hint

Use square brackets [] to create a list. Each book is a dictionary with keys 'title' and 'author'.

2

Create a variable to count books

Create a variable called book_count and set it to the length of the books list using the len() function.

Python

books = [
    {'title': '1984', 'author': 'George Orwell'},
    {'title': 'To Kill a Mockingbird', 'author': 'Harper Lee'},
    {'title': 'The Great Gatsby', 'author': 'F. Scott Fitzgerald'}
]
# Create book_count variable with length of books
# Your code here

Hint

Use len(books) to get how many books are in the list.

3

Print each book's details using a for loop

Use a for loop with variable book to iterate over books. Inside the loop, print the book's title and author in this exact format: Title: 1984, Author: George Orwell.

Python

books = [
    {'title': '1984', 'author': 'George Orwell'},
    {'title': 'To Kill a Mockingbird', 'author': 'Harper Lee'},
    {'title': 'The Great Gatsby', 'author': 'F. Scott Fitzgerald'}
]
book_count = len(books)
# Use a for loop to print each book's title and author
# Your code here

Hint

Use for book in books: to loop. Use an f-string to print the title and author.

4

Create a Book class and print book details using objects

Define a class called Book with an __init__ method that takes title and author parameters and stores them as attributes. Add a method called display that prints the book's title and author in the format: Title: 1984, Author: George Orwell. Create a list called book_objects with three Book objects using the same titles and authors as before. Use a for loop with variable book to call the display method on each object.

Python

books = [
    {'title': '1984', 'author': 'George Orwell'},
    {'title': 'To Kill a Mockingbird', 'author': 'Harper Lee'},
    {'title': 'The Great Gatsby', 'author': 'F. Scott Fitzgerald'}
]
book_count = len(books)
for book in books:
    print(f"Title: {book['title']}, Author: {book['author']}")

# Define Book class and create book_objects list
# Your code here

Hint

Define a class with __init__ to set attributes. Add a method display to print details. Create objects and store in a list. Loop over the list and call display.

Practice

1. Which statement best describes the main difference between procedural and object-oriented programming in Python?

easy

A. Procedural programming is faster than object-oriented programming in all cases.

B. Procedural programming is only for small programs; object-oriented programming is for large programs.

C. Procedural programming cannot use variables; object-oriented programming can.

D. Procedural programming uses functions and step-by-step instructions; object-oriented programming uses classes and objects.

Solution

1. Step 1: Understand procedural programming basics

   Procedural programming organizes code as functions and instructions executed in order.

2. Step 2: Understand object-oriented programming basics

   Object-oriented programming organizes code using classes and objects that combine data and behavior.

3. Final Answer:

   Procedural programming uses functions and step-by-step instructions; object-oriented programming uses classes and objects. -> Option D

4. Quick Check:

   Procedural = functions, OOP = classes/objects [OK]

Hint: Procedural = steps; OOP = objects/classes [OK]

Common Mistakes:

• Thinking procedural can't use variables
• Believing OOP is always slower
• Confusing program size with programming style

2. Which of the following is the correct way to define a class in Python?

easy

A. def MyClass(): pass

B. class MyClass(): pass

C. function MyClass() {}

D. class MyClass[]: pass

Solution

1. Step 1: Recall Python class syntax

   In Python, classes are defined using the keyword class followed by the class name and parentheses.

2. Step 2: Check each option

   class MyClass(): pass uses correct Python syntax. def MyClass(): pass uses def which defines a function, not a class. function MyClass() {} uses JavaScript syntax. class MyClass[]: pass uses invalid brackets.

3. Final Answer:

   class MyClass(): pass -> Option B

4. Quick Check:

   Python classes start with 'class' keyword [OK]

Hint: Classes start with 'class' keyword in Python [OK]

Common Mistakes:

• Using def instead of class
• Using wrong brackets [] instead of ()
• Confusing Python with other languages syntax

3. What will be the output of this Python code?

def greet(name):
    return f"Hello, {name}!"

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

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

medium

A. TypeError

B. Hello, name!

C. Hello, Anna!

D. AttributeError

Solution

1. Step 1: Understand the procedural function greet

   The function greet(name) returns the string "Hello, {name}!" with the given name.

2. Step 2: Understand the Person class and method call

   The Person class stores the name and its greet method calls the procedural greet function with self.name. Creating p with name "Anna" and calling p.greet() returns "Hello, Anna!".

3. Final Answer:

   Hello, Anna! -> Option C

4. Quick Check:

   Class method calls procedural function correctly [OK]

Hint: Class method calls function with self.name [OK]

Common Mistakes:

• Confusing variable name with string 'name'
• Expecting error due to mixing styles
• Forgetting to use self.name

4. Identify the error in this code that mixes procedural and object-oriented styles:

class Calculator:
    def add(self, a, b):
        return a + b

result = Calculator.add(3, 4)
print(result)

medium

A. Missing self argument when calling add method

B. Class Calculator is not defined

C. add method should not return a value

D. print statement syntax error

Solution

1. Step 1: Understand method call on class vs instance

   The add method is an instance method requiring a self parameter. Calling Calculator.add(3, 4) misses the self argument.

2. Step 2: Correct usage

   To fix, create an instance: calc = Calculator() then call calc.add(3, 4). This passes self automatically.

3. Final Answer:

   Missing self argument when calling add method -> Option A

4. Quick Check:

   Instance methods need self, call via instance [OK]

Hint: Call instance methods on object, not class [OK]

Common Mistakes:

• Calling instance method directly on class
• Ignoring self parameter
• Assuming methods are static by default

5. You want to convert this procedural code into an object-oriented style. Which class design correctly encapsulates the data and behavior?

# Procedural code
def area_rectangle(width, height):
    return width * height

w = 5
h = 3
print(area_rectangle(w, h))

hard

A. class Rectangle:
def __init__(self, width, height):
self.width = width
self.height = height
def area(self):
return self.width * self.height

B. class Rectangle:
def area(width, height):
return width * height

C. class Rectangle:
def __init__(self):
pass
def area(self):
return width * height

D. class Rectangle:
def __init__(self, width, height):
return width * height

Solution

1. Step 1: Identify data and behavior to encapsulate

   The procedural code uses width and height as data and area_rectangle as behavior. In OOP, these should be inside a class.

2. Step 2: Check class options for correct encapsulation

   class Rectangle: def __init__(self, width, height): self.width = width self.height = height def area(self): return self.width * self.height stores width and height as instance variables and defines area() method using them. Other options either miss self, lack data storage, or misuse return in constructor.

3. Final Answer:

   class Rectangle with __init__ storing width and height, and area method using them -> Option A

4. Quick Check:

   OOP encapsulates data and behavior in class [OK]

Hint: Store data in __init__, use methods for behavior [OK]

Common Mistakes:

• Not using self for instance variables
• Returning values from __init__
• Defining methods without self parameter