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Object-Oriented-Programming-in-Python.html
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19 ноя 2025, 13:13
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<body>
    <div class="container">
        <header>
            <h1>Object-Oriented Programming in Python</h1>
            <p class="subtitle">Explained in Plain English</p>
            <!-- Removed Einstein quote -->
            <p>An interactive guide to understanding OOP concepts with Python examples</p>
        </header>

        <section class="section">
            <h2>What is OOP?</h2>
            <p>Object-oriented programming is a popular way to write computer programs that organizes code around objects rather than actions.</p>
            
            <img src="assets/image/OOP_Images/Image1.png" alt="Introduction to OOP" class="presentation-image">
            
            <div class="analogy">
                <h4>The House Building Analogy</h4>
                <p>Imagine you run a construction company building 100 houses. Instead of designing each house from scratch, you use the same blueprint for all houses.</p>
                <ul>
                    <li><strong>Blueprint</strong> = Class</li>
                    <li><strong>House</strong> = Instance of a class or object</li>
                    <li><strong>House-oriented building</strong> = Object-oriented programming</li>
                </ul>
            </div>
            
            <p>Just as house-oriented building is efficient for constructing homes, OOP is efficient for writing computer programs.</p>
        </section>

        <section class="section">
            <h2>The Four Pillars of OOP</h2>
            <img src="assets/image/OOP_Images/Image2.png" alt="Four Pillars of OOP" class="presentation-image">
            
            <div class="pillars">
                <div class="pillar">
                    <h4>Polymorphism</h4>
                    <p>Ability of an object to take many forms</p>
                    <p><em>Example: A house can have different types of roofs, windows, doors</em></p>
                </div>
                <div class="pillar">
                    <h4>Inheritance</h4>
                    <p>Child classes acquire properties from parent classes</p>
                    <p><em>Example: A house gaining a new feature like a garage</em></p>
                </div>
                <div class="pillar">
                    <h4>Encapsulation</h4>
                    <p>Protects data and methods from outside misuse</p>
                    <p><em>Example: Keeping kids out of the garage with a key</em></p>
                </div>
                <div class="pillar">
                    <h4>Abstraction</h4>
                    <p>Hides unnecessary details from the user</p>
                    <p><em>Example: Considering the final house, not construction materials</em></p>
                </div>
            </div>
        </section>

        <section class="section">
            <h2>Classes and Instances</h2>
            <p>A class is a blueprint that defines how an instance (object) will look and behave.</p>
            
            <img src="assets/image/OOP_Images/Image3.png" alt="Classes and Instances" class="presentation-image">
            
            <h3>Creating Classes Manually</h3>
            <div class="code-block">
                <span class="code-keyword">class</span> <span class="code-function">house</span>():<br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">pass</span><br>
                <br>
                house1 = house()<br>
                house2 = house()<br>
                <br>
                house1.address = 1234<br>
                house1.state = <span class="code-string">"california"</span><br>
                house1.Alarm = <span class="code-keyword">False</span><br>
                house1.price = 300000<br>
                <br>
                house2.address = 5678<br>
                house2.state = <span class="code-string">"texas"</span><br>
                house2.Alarm = <span class="code-keyword">True</span><br>
                house2.price = 100000<br>
                <br>
                <span class="code-function">print</span>(house1.state)<br>
                <span class="code-function">print</span>(house2.price)<br>
                <br>
                <span class="code-comment"># Output:</span><br>
                <span class="code-comment"># california</span><br>
                <span class="code-comment"># 100000</span>
            </div>
            
            <p>This approach works but is inefficient for creating many objects. Let's improve it with <code>__init__</code>.</p>
            
            <div class="exercise-container">
                <div class="exercise-header">Exercise 1: Creating a Simple Class</div>
                <div class="exercise-description">
                    Create a class called "Car" with attributes: brand, model, and year. Then create an instance of this class.
                </div>
                <textarea class="code-editor" id="exercise1-editor"># Write your code here
# 1. Create a Car class with __init__ method
# 2. Add brand, model, and year parameters
# 3. Create an instance of your Car class
# 4. Print the car's details

class Car:
    pass  # Replace this with your implementation

# Create an instance here</textarea>
                <div class="exercise-buttons">
                    <button class="exercise-btn" onclick="checkExercise1()">Check Answer</button>
                    <button class="exercise-btn" onclick="resetExercise1()">Reset</button>
                    <button class="exercise-btn" onclick="showSolution1()">Show Solution</button>
                </div>
                <div class="exercise-output" id="exercise1-output">Run your code to see output here...</div>
            </div>
        </section>

        <section class="section">
            <h2>Creating Classes with __init__</h2>
            <p>The <code>__init__</code> method is Python's constructor that initializes new objects.</p>
            
            <img src="assets/image/OOP_Images/Image4.png" alt="Creating Classes with __init__" class="presentation-image">
            
            <div class="code-block">
                <span class="code-keyword">class</span> <span class="code-function">house</span>():<br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">__init__</span>(<span class="code-var">self</span>, address, state, Alarm, price):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.address = address<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.state = state<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.Alarm = Alarm<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.price = price<br>
                <br>
                house1 = house(1234, <span class="code-string">"california"</span>, <span class="code-keyword">False</span>, 300000)<br>
                house2 = house(5678, <span class="code-string">"texas"</span>, <span class="code-keyword">True</span>, 100000)<br>
                <br>
                <span class="code-function">print</span>(house1.state)<br>
                <span class="code-function">print</span>(house2.price)<br>
                <br>
                <span class="code-comment"># Output:</span><br>
                <span class="code-comment"># california</span><br>
                <span class="code-comment"># 100000</span>
            </div>
            
            <h3>What is the self Keyword?</h3>
            <p><code>self</code> refers to the instance of the class. It allows you to access attributes and methods of the object.</p>
            
            <img src="assets/image/OOP_Images/Image5.png" alt="Understanding the self keyword" class="presentation-image">
            
            <div class="exercise-container">
                <div class="exercise-header">Exercise 2: Using __init__ method</div>
                <div class="exercise-description">
                    Improve your Car class by adding an __init__ method to initialize the attributes.
                </div>
                <textarea class="code-editor" id="exercise2-editor"># Write your code here
# 1. Create a Car class with __init__ method
# 2. Initialize brand, model, and year attributes
# 3. Create two instances with different values
# 4. Print details of both cars

class Car:
    pass  # Replace this with your implementation

# Create two instances here</textarea>
                <div class="exercise-buttons">
                    <button class="exercise-btn" onclick="checkExercise2()">Check Answer</button>
                    <button class="exercise-btn" onclick="resetExercise2()">Reset</button>
                </div>
                <div class="exercise-output" id="exercise2-output">Run your code to see output here...</div>
            </div>
            
            <div class="code-block">
                <span class="code-keyword">class</span> <span class="code-function">house</span>():<br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">__init__</span>(<span class="code-var">self</span>, address, street, state):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.address = address<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.street = street<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.state = state<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.completeAddress = <span class="code-function">str</span>(address) + <span class="code-string">" "</span> + state<br>
                <br>
                house = house(1234, <span class="code-string">"california"</span>, <span class="code-string">"awesome road"</span>)<br>
                <br>
                <span class="code-function">print</span>(house.completeAddress)<br>
                <br>
                <span class="code-comment"># Output:</span><br>
                <span class="code-comment"># 1234 awesome road</span>
            </div>
        </section>

        <section class="section">
            <h2>Instance Variables vs Class Variables</h2>
            
            <img src="assets/image/OOP_Images/Image6.png" alt="Instance Variables vs Class Variables" class="presentation-image">
            
            <div class="comparison">
                <div class="comparison-item">
                    <h3>Instance Variables</h3>
                    <p>Unique to each instance of the class</p>
                    <ul>
                        <li>Address</li>
                        <li>State</li>
                        <li>Alarm status</li>
                        <li>Price</li>
                    </ul>
                    <p><em>Like the sofa in each house - can be different</em></p>
                </div>
                
                <div class="comparison-item">
                    <h3>Class Variables</h3>
                    <p>Shared by all instances of the class</p>
                    <ul>
                        <li>Company name</li>
                        <li>Common features (like a carpet)</li>
                    </ul>
                    <p><em>Like the company name - same for all houses</em></p>
                </div>
            </div>
            
            <div class="code-block">
                <span class="code-keyword">class</span> <span class="code-function">house</span>():<br>
                <br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-comment"># Class variable</span><br>
                &nbsp;&nbsp;&nbsp;&nbsp;company_name = <span class="code-string">"Awesome building company"</span><br>
                <br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">__init__</span>(<span class="code-var">self</span>, address, state, Alarm, price):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-comment"># Instance variables</span><br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.address = address<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.state = state<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.Alarm = Alarm<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.price = price<br>
                <br>
                house1 = house(1234, <span class="code-string">"california"</span>, <span class="code-keyword">False</span>, 300000)<br>
                house2 = house(5678, <span class="code-string">"texas"</span>, <span class="code-keyword">True</span>, 100000)<br>
                <br>
                <span class="code-comment"># Accessing class variable</span><br>
                <span class="code-function">print</span>(house1.company_name)<br>
                <span class="code-function">print</span>(house2.company_name)<br>
                <br>
                <span class="code-comment"># Output:</span><br>
                <span class="code-comment"># Awesome building company</span>
                <span class="code-comment"># Awesome building company</span>
            </div>
            
            <div class="exercise-container">
                <div class="exercise-header">Exercise 3: Instance vs Class Variables</div>
                <div class="exercise-description">
                    Create a Student class with both instance variables (name, grade) and class variables (school_name).
                </div>
                <textarea class="code-editor" id="exercise3-editor"># Write your code here
# 1. Create a Student class
# 2. Add a class variable school_name = "Tech High"
# 3. Add an __init__ method with name and grade parameters
# 4. Create two student instances
# 5. Print both instance data and the class variable

class Student:
    pass  # Replace with your implementation

# Create instances and print data</textarea>
                <div class="exercise-buttons">
                    <button class="exercise-btn" onclick="checkExercise3()">Check Answer</button>
                    <button class="exercise-btn" onclick="resetExercise3()">Reset</button>
                </div>
                <div class="exercise-output" id="exercise3-output">Run your code to see output here...</div>
            </div>
        </section>

        <section class="section">
            <h2>Methods in OOP</h2>
            <p>Methods are functions defined inside a class that define the behaviors of objects.</p>
            
            <img src="assets/image/OOP_Images/Image7.png" alt="Methods in OOP" class="presentation-image">
            
            <h3>Instance Method Example</h3>
            <p>Let's create a method to adjust house prices for inflation:</p>
            
            <div class="code-block">
                <span class="code-keyword">class</span> <span class="code-function">house</span>():<br>
                <br>
                &nbsp;&nbsp;&nbsp;&nbsp;company_name = <span class="code-string">"Awesome building company"</span><br>
                &nbsp;&nbsp;&nbsp;&nbsp;inflation_coefficient = 1.08<br>
                <br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">__init__</span>(<span class="code-var">self</span>, address, state, Alarm, price):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.address = address<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.state = state<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.Alarm = Alarm<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.price = price<br>
                <br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-comment"># Instance method</span><br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">correctPriceMethod</span>(<span class="code-var">self</span>):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.price = <span class="code-var">self</span>.price * <span class="code-var">self</span>.inflation_coefficient<br>
                <br>
                apartment1 = house(1234, <span class="code-string">"california"</span>, <span class="code-keyword">False</span>, 300000)<br>
                <br>
                <span class="code-function">print</span>(<span class="code-string">"Original price:"</span>, apartment1.price)<br>
                <br>
                apartment1.correctPriceMethod()<br>
                <br>
                <span class="code-function">print</span>(<span class="code-string">"Adjusted price:"</span>, apartment1.price)<br>
                <br>
                <span class="code-comment"># Output:</span><br>
                <span class="code-comment"># Original price: 300000</span><br>
                <span class="code-comment"># Adjusted price: 324000</span>
            </div>
            
            <div class="exercise-container">
                <div class="exercise-header">Exercise 4: Adding Methods to Classes</div>
                <div class="exercise-description">
                    Add a method to calculate the age of a car based on its year of manufacture.
                </div>
                <textarea class="code-editor" id="exercise4-editor"># Write your code here
# 1. Create a Car class with brand, model, and year attributes
# 2. Add a method get_car_age() that returns the car's age (2025 - year)
# 3. Create an instance and test your method

class Car:
    pass  # Replace with your implementation

# Create instance and test method</textarea>
                <div class="exercise-buttons">
                    <button class="exercise-btn" onclick="checkExercise4()">Check Answer</button>
                    <button class="exercise-btn" onclick="resetExercise4()">Reset</button>
                </div>
                <div class="exercise-output" id="exercise4-output">Run your code to see output here...</div>
            </div>
            
            <div class="interactive-demo">
                <h3>Try It Yourself: House Price Calculator</h3>
                <div class="demo-controls">
                    <button id="createHouse">Create a New House</button>
                    <button id="adjustPrice">Adjust Price for Inflation</button>
                    <button id="reset">Reset</button>
                </div>
                <div class="output" id="demoOutput">
                    Click "Create a New House" to start
                </div>
            </div>
        </section>

        <!-- New section on Encapsulation -->
        <section class="section">
            <h2>Encapsulation</h2>
            <p>Encapsulation is the process of preventing clients from accessing certain properties, which can only be accessed through specific methods.</p>
            
            <div class="key-concept">
                <h3>Key Concept</h3>
                <p>Private attributes are inaccessible attributes, and information hiding is the process of making particular attributes private. You use two underscores to declare private characteristics.</p>
            </div>
            
            <div class="code-block">
                <span class="code-keyword">class</span> <span class="code-function">Book</span>:<br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">__init__</span>(<span class="code-var">self</span>, title, quantity, author, price):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.title = title<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.quantity = quantity<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.author = author<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.price = price<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.__discount = 0.10&nbsp;&nbsp;<span class="code-comment"># Private attribute</span><br>
                <br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">__repr__</span>(<span class="code-var">self</span>):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">return</span> <span class="code-function">f</span><span class="code-string">"Book: {self.title}, Quantity: {self.quantity}, Author: {self.author}, Price: {self.price}"</span><br>
                <br>
                book1 = Book(<span class="code-string">'Book 1'</span>, 12, <span class="code-string">'Author 1'</span>, 120)<br>
                <br>
                <span class="code-function">print</span>(book1.title)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-comment"># Accessible</span><br>
                <span class="code-function">print</span>(book1.__discount)&nbsp;&nbsp;<span class="code-comment"># Not accessible - will cause an error</span>
            </div>
            
            <h3>Getter and Setter Methods</h3>
            <p>We use getter and setter methods to access private attributes.</p>
            
            <div class="code-block">
                <span class="code-keyword">class</span> <span class="code-function">Book</span>:<br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">__init__</span>(<span class="code-var">self</span>, title, quantity, author, price):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.title = title<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.quantity = quantity<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.author = author<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.__price = price&nbsp;&nbsp;<span class="code-comment"># Private attribute</span><br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.__discount = <span class="code-keyword">None</span><br>
                <br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">set_discount</span>(<span class="code-var">self</span>, discount):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.__discount = discount<br>
                <br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">get_price</span>(<span class="code-var">self</span>):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">if</span> <span class="code-var">self</span>.__discount:<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">return</span> <span class="code-var">self</span>.__price * (1-<span class="code-var">self</span>.__discount)<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">return</span> <span class="code-var">self</span>.__price<br>
                <br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">__repr__</span>(<span class="code-var">self</span>):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">return</span> <span class="code-function">f</span><span class="code-string">"Book: {self.title}, Quantity: {self.quantity}, Author: {self.author}, Price: {self.get_price()}"</span><br>
                <br>
                single_book = Book(<span class="code-string">'Two States'</span>, 1, <span class="code-string">'Chetan Bhagat'</span>, 200)<br>
                bulk_books = Book(<span class="code-string">'Two States'</span>, 25, <span class="code-string">'Chetan Bhagat'</span>, 200)<br>
                bulk_books.set_discount(0.20)&nbsp;&nbsp;<span class="code-comment"># 20% discount for bulk purchase</span><br>
                <br>
                <span class="code-function">print</span>(single_book.get_price())&nbsp;&nbsp;<span class="code-comment"># 200</span><br>
                <span class="code-function">print</span>(bulk_books.get_price())&nbsp;&nbsp;&nbsp;<span class="code-comment"># 160.0</span>
            </div>
            
            <div class="exercise-container">
                <div class="exercise-header">Exercise 5: Encapsulation with Bank Account</div>
                <div class="exercise-description">
                    Create a BankAccount class with a private balance attribute. Add methods to deposit, withdraw, and check balance.
                </div>
                <textarea class="code-editor" id="exercise5-editor"># Write your code here
# 1. Create a BankAccount class
# 2. Add __init__ method with account_holder parameter
# 3. Add a private __balance attribute, initialized to 0
# 4. Add deposit(amount) method to add to balance
# 5. Add withdraw(amount) method to subtract from balance (if sufficient funds)
# 6. Add get_balance() method to return current balance
# 7. Test your class with some transactions

class BankAccount:
    pass  # Replace with your implementation

# Test your implementation</textarea>
                <div class="exercise-buttons">
                    <button class="exercise-btn" onclick="checkExercise5()">Check Answer</button>
                    <button class="exercise-btn" onclick="resetExercise5()">Reset</button>
                    <button class="exercise-btn" onclick="showSolution5()">Show Solution</button>
                </div>
                <div class="exercise-output" id="exercise5-output">Run your code to see output here...</div>
            </div>
        </section>

        <!-- New section on Inheritance -->
        <section class="section">
            <h2>Inheritance</h2>
            <p>Inheritance is regarded as the most significant characteristics of OOP. A class's ability to inherit methods and/or characteristics from another class is known as inheritance.</p>
            
            <div class="key-concept">
                <h3>Key Concept</h3>
                <p>The subclass or child class is the class that inherits. The superclass or parent class is the class from which methods and/or attributes are inherited.</p>
            </div>
            
            <div class="code-block">
                <span class="code-keyword">class</span> <span class="code-function">Book</span>:<br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">__init__</span>(<span class="code-var">self</span>, title, quantity, author, price):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.title = title<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.quantity = quantity<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.author = author<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.__price = price<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.__discount = <span class="code-keyword">None</span><br>
                <br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">set_discount</span>(<span class="code-var">self</span>, discount):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.__discount = discount<br>
                <br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">get_price</span>(<span class="code-var">self</span>):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">if</span> <span class="code-var">self</span>.__discount:<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">return</span> <span class="code-var">self</span>.__price * (1-<span class="code-var">self</span>.__discount)<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">return</span> <span class="code-var">self</span>.__price<br>
                <br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">__repr__</span>(<span class="code-var">self</span>):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">return</span> <span class="code-function">f</span><span class="code-string">"Book: {self.title}, Quantity: {self.quantity}, Author: {self.author}, Price: {self.get_price()}"</span><br>
                <br>
                <span class="code-comment"># Novel class inheriting from Book</span><br>
                <span class="code-keyword">class</span> <span class="code-function">Novel</span>(Book):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">__init__</span>(<span class="code-var">self</span>, title, quantity, author, price, pages):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-function">super</span>().<span class="code-function">__init__</span>(title, quantity, author, price)&nbsp;&nbsp;<span class="code-comment"># Call parent constructor</span><br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.pages = pages<br>
                <br>
                <span class="code-comment"># Academic class inheriting from Book</span><br>
                <span class="code-keyword">class</span> <span class="code-function">Academic</span>(Book):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">__init__</span>(<span class="code-var">self</span>, title, quantity, author, price, branch):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-function">super</span>().<span class="code-function">__init__</span>(title, quantity, author, price)&nbsp;&nbsp;<span class="code-comment"># Call parent constructor</span><br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.branch = branch<br>
                <br>
                novel1 = Novel(<span class="code-string">'Two States'</span>, 20, <span class="code-string">'Chetan Bhagat'</span>, 200, 187)<br>
                novel1.set_discount(0.20)<br>
                <br>
                academic1 = Academic(<span class="code-string">'Python Foundations'</span>, 12, <span class="code-string">'PSF'</span>, 655, <span class="code-string">'IT'</span>)<br>
                <br>
                <span class="code-function">print</span>(novel1)<br>
                <span class="code-function">print</span>(academic1)
            </div>
            
            <div class="exercise-container">
                <div class="exercise-header">Exercise 6: Inheritance with Animals</div>
                <div class="exercise-description">
                    Create an Animal base class and Dog and Cat subclasses that inherit from it.
                </div>
                <textarea class="code-editor" id="exercise6-editor"># Write your code here
# 1. Create an Animal class with name and species attributes
# 2. Add a make_sound() method that prints a generic sound
# 3. Create Dog and Cat classes that inherit from Animal
# 4. Override make_sound() in each subclass to make animal-specific sounds
# 5. Add breed attribute to Dog and color attribute to Cat
# 6. Test your classes

class Animal:
    pass  # Replace with your implementation

class Dog:
    pass  # Replace with your implementation

class Cat:
    pass  # Replace with your implementation

# Test your implementation</textarea>
                <div class="exercise-buttons">
                    <button class="exercise-btn" onclick="checkExercise6()">Check Answer</button>
                    <button class="exercise-btn" onclick="resetExercise6()">Reset</button>
                    <button class="exercise-btn" onclick="showSolution6()">Show Solution</button>
                </div>
                <div class="exercise-output" id="exercise6-output">Run your code to see output here...</div>
            </div>
        </section>

        <!-- New section on Polymorphism -->
        <section class="section">
            <h2>Polymorphism</h2>
            <p>The term 'polymorphism' means 'something that takes on multiple forms.' In OOP, it refers to a subclass's ability to adapt a method that already exists in its superclass to meet its needs.</p>
            
            <div class="key-concept">
                <h3>Key Concept</h3>
                <p>A subclass can use a method from its superclass as is or modify it as needed. This allows objects of different types to be treated as instances of the same type through a common interface.</p>
            </div>
            
            <div class="code-block">
                <span class="code-keyword">class</span> <span class="code-function">Academic</span>(Book):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">__init__</span>(<span class="code-var">self</span>, title, quantity, author, price, branch):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-function">super</span>().<span class="code-function">__init__</span>(title, quantity, author, price)<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.branch = branch<br>
                <br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">__repr__</span>(<span class="code-var">self</span>):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">return</span> <span class="code-function">f</span><span class="code-string">"Book: {self.title}, Branch: {self.branch}, Quantity: {self.quantity}, Author: {self.author}, Price: {self.get_price()}"</span><br>
                <br>
                novel1 = Novel(<span class="code-string">'Two States'</span>, 20, <span class="code-string">'Chetan Bhagat'</span>, 200, 187)<br>
                novel1.set_discount(0.20)<br>
                <br>
                academic1 = Academic(<span class="code-string">'Python Foundations'</span>, 12, <span class="code-string">'PSF'</span>, 655, <span class="code-string">'IT'</span>)<br>
                <br>
                <span class="code-function">print</span>(novel1)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-comment"># Uses Book's __repr__ method</span><br>
                <span class="code-function">print</span>(academic1)&nbsp;&nbsp;&nbsp;<span class="code-comment"># Uses Academic's own __repr__ method</span>
            </div>
            
            <div class="exercise-container">
                <div class="exercise-header">Exercise 7: Polymorphism with Shapes</div>
                <div class="exercise-description">
                    Create a Shape base class and Circle and Rectangle subclasses. Implement area calculation with polymorphism.
                </div>
                <textarea class="code-editor" id="exercise7-editor"># Write your code here
# 1. Create a Shape class with an area() method that returns 0
# 2. Create Circle and Rectangle classes that inherit from Shape
# 3. Override area() in each subclass with appropriate calculations
# 4. Add necessary attributes in __init__ methods (radius for Circle, width/height for Rectangle)
# 5. Test your classes

class Shape:
    pass  # Replace with your implementation

class Circle:
    pass  # Replace with your implementation

class Rectangle:
    pass  # Replace with your implementation

# Test your implementation</textarea>
                <div class="exercise-buttons">
                    <button class="exercise-btn" onclick="checkExercise7()">Check Answer</button>
                    <button class="exercise-btn" onclick="resetExercise7()">Reset</button>
                    <button class="exercise-btn" onclick="showSolution7()">Show Solution</button>
                </div>
                <div class="exercise-output" id="exercise7-output">Run your code to see output here...</div>
            </div>
        </section>

        <!-- New section on Abstraction -->
        <section class="section">
            <h2>Abstraction</h2>
            <p>Abstraction isn't supported directly in Python, but calling a magic method allows for abstraction. If an abstract method is declared in a superclass, subclasses that inherit from the superclass must have their own implementation of the method.</p>
            
            <div class="key-concept">
                <h3>Key Concept</h3>
                <p>A superclass's abstract method will never be called by its subclasses. But the abstraction aids in the maintenance of a similar structure across all subclasses.</p>
            </div>
            
            <div class="code-block">
                <span class="code-keyword">from</span> abc <span class="code-keyword">import</span> ABC, abstractmethod<br>
                <br>
                <span class="code-keyword">class</span> <span class="code-function">Book</span>(ABC):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">__init__</span>(<span class="code-var">self</span>, title, quantity, author, price):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.title = title<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.quantity = quantity<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.author = author<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.__price = price<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.__discount = <span class="code-keyword">None</span><br>
                <br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">set_discount</span>(<span class="code-var">self</span>, discount):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.__discount = discount<br>
                <br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">get_price</span>(<span class="code-var">self</span>):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">if</span> <span class="code-var">self</span>.__discount:<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">return</span> <span class="code-var">self</span>.__price * (1-<span class="code-var">self</span>.__discount)<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">return</span> <span class="code-var">self</span>.__price<br>
                <br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-decorator">@abstractmethod</span><br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">__repr__</span>(<span class="code-var">self</span>):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">return</span> <span class="code-function">f</span><span class="code-string">"Book: {self.title}, Quantity: {self.quantity}, Author: {self.author}, Price: {self.get_price()}"</span><br>
                <br>
                <span class="code-keyword">class</span> <span class="code-function">Novel</span>(Book):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">__init__</span>(<span class="code-var">self</span>, title, quantity, author, price, pages):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-function">super</span>().<span class="code-function">__init__</span>(title, quantity, author, price)<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.pages = pages<br>
                <br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">__repr__</span>(<span class="code-var">self</span>):&nbsp;&nbsp;<span class="code-comment"># Must implement abstract method</span><br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">return</span> <span class="code-function">f</span><span class="code-string">"Book: {self.title}, Quantity: {self.quantity}, Author: {self.author}, Price: {self.get_price()}"</span><br>
                <br>
                <span class="code-keyword">class</span> <span class="code-function">Academic</span>(Book):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">__init__</span>(<span class="code-var">self</span>, title, quantity, author, price, branch):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-function">super</span>().<span class="code-function">__init__</span>(title, quantity, author, price)<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-var">self</span>.branch = branch<br>
                <br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">__repr__</span>(<span class="code-var">self</span>):&nbsp;&nbsp;<span class="code-comment"># Must implement abstract method</span><br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">return</span> <span class="code-function">f</span><span class="code-string">"Book: {self.title}, Branch: {self.branch}, Quantity: {self.quantity}, Author: {self.author}, Price: {self.get_price()}"</span><br>
                <br>
                novel1 = Novel(<span class="code-string">'Two States'</span>, 20, <span class="code-string">'Chetan Bhagat'</span>, 200, 187)<br>
                novel1.set_discount(0.20)<br>
                <br>
                academic1 = Academic(<span class="code-string">'Python Foundations'</span>, 12, <span class="code-string">'PSF'</span>, 655, <span class="code-string">'IT'</span>)<br>
                <br>
                <span class="code-function">print</span>(novel1)<br>
                <span class="code-function">print</span>(academic1)
            </div>
        </section>

        <!-- New section on Method Overloading -->
        <section class="section">
            <h2>Method Overloading</h2>
            <p>Method overloading refers to the use of many methods with the same name that take various numbers of arguments within a single class. Python doesn't support Method Overloading by default.</p>
            
            <div class="key-concept">
                <h3>Key Concept</h3>
                <p>Python only remembers the most recent definition of a method. When multiple methods with the same name are defined, the last one overwrites the previous ones.</p>
            </div>
            
            <div class="code-block">
                <span class="code-keyword">class</span> <span class="code-function">OverloadingDemo</span>:<br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">add</span>(<span class="code-var">self</span>, x, y):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-function">print</span>(x+y)<br>
                <br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">add</span>(<span class="code-var">self</span>, x, y, z):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-function">print</span>(x+y+z)<br>
                <br>
                obj = OverloadingDemo()<br>
                obj.add(2, 3)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-comment"># Error! Missing argument z</span>
            </div>
            
            <p>To achieve method overloading in Python, we can use default parameters:</p>
            
            <div class="code-block">
                <span class="code-keyword">class</span> <span class="code-function">Calculator</span>:<br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">add</span>(<span class="code-var">self</span>, x, y, z=0):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">return</span> x + y + z<br>
                <br>
                calc = Calculator()<br>
                <span class="code-function">print</span>(calc.add(2, 3))&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-comment"># 5</span><br>
                <span class="code-function">print</span>(calc.add(2, 3, 4))&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-comment"># 9</span>
            </div>
        </section>

        <!-- New section on Method Overriding -->
        <section class="section">
            <h2>Method Overriding</h2>
            <p>When a method with the same name and arguments is used in both a derived class and a base or super class, we say that the derived class method "overrides" the method provided in the base class.</p>
            
            <div class="key-concept">
                <h3>Key Concept</h3>
                <p>When the overridden method gets called, the derived class's method is always invoked. The method that was used in the base class is now hidden.</p>
            </div>
            
            <div class="code-block">
                <span class="code-keyword">class</span> <span class="code-function">ParentClass</span>:<br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">call_me</span>(<span class="code-var">self</span>):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-function">print</span>(<span class="code-string">"I am parent class"</span>)<br>
                <br>
                <span class="code-keyword">class</span> <span class="code-function">ChildClass</span>(ParentClass):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">call_me</span>(<span class="code-var">self</span>):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-function">print</span>(<span class="code-string">"I am child class"</span>)<br>
                <br>
                pobj = ParentClass()<br>
                pobj.call_me()&nbsp;&nbsp;<span class="code-comment"># Output: I am parent class</span><br>
                <br>
                cobj = ChildClass()<br>
                cobj.call_me()&nbsp;&nbsp;<span class="code-comment"># Output: I am child class</span>
            </div>
            
            <p>We can invoke the parent class's method from the child class using <code>super()</code>:</p>
            
            <div class="code-block">
                <span class="code-keyword">class</span> <span class="code-function">ParentClass</span>:<br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">call_me</span>(<span class="code-var">self</span>):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-function">print</span>(<span class="code-string">"I am parent class"</span>)<br>
                <br>
                <span class="code-keyword">class</span> <span class="code-function">ChildClass</span>(ParentClass):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;<span class="code-keyword">def</span> <span class="code-function">call_me</span>(<span class="code-var">self</span>):<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-function">print</span>(<span class="code-string">"I am child class"</span>)<br>
                &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<span class="code-function">super</span>().<span class="code-function">call_me</span>()&nbsp;&nbsp;<span class="code-comment"># Call parent method</span><br>
                <br>
                pobj = ParentClass()<br>
                pobj.call_me()&nbsp;&nbsp;<span class="code-comment"># Output: I am parent class</span><br>
                <br>
                cobj = ChildClass()<br>
                cobj.call_me()&nbsp;&nbsp;<span class="code-comment"># Output: I am child class \n I am parent class</span>
            </div>
            
            <div class="exercise-container">
                <div class="exercise-header">Exercise 8: Method Overriding</div>
                <div class="exercise-description">
                    Create a Vehicle class and a Car subclass that overrides a method from the parent class.
                </div>
                <textarea class="code-editor" id="exercise8-editor"># Write your code here
# 1. Create a Vehicle class with start_engine() method that prints "Vehicle engine started"
# 2. Create a Car class that inherits from Vehicle
# 3. Override start_engine() in Car to print "Car engine started"
# 4. Add a call to super().start_engine() in the Car's start_engine method
# 5. Test both classes

class Vehicle:
    pass  # Replace with your implementation

class Car:
    pass  # Replace with your implementation

# Test your implementation</textarea>
                <div class="exercise-buttons">
                    <button class="exercise-btn" onclick="checkExercise8()">Check Answer</button>
                    <button class="exercise-btn" onclick="resetExercise8()">Reset</button>
                    <button class="exercise-btn" onclick="showSolution8()">Show Solution</button>
                </div>
                <div class="exercise-output" id="exercise8-output">Run your code to see output here...</div>
            </div>
        </section>

        <section class="section">
            <h2>OOP in Different Languages</h2>
            
            <img src="assets/image/OOP_Images/Image9.png" alt="OOP in Different Languages" class="presentation-image">
            
            <div class="comparison">
                <div class="comparison-item">
                    <h3>Java</h3>
                    <p>Designed specifically for OOP. You create classes and objects to structure your code.</p>
                    <p><em>Like creating blueprints and then building with those blueprints.</em></p>
                </div>
                
                <div class="comparison-item">
                    <h3>C</h3>
                    <p>Works in a more procedural manner. Following a recipe step by step instead of using blueprints.</p>
                </div>
                
                <div class="comparison-item">
                    <h3>Python</h3>
                    <p>A flexible language that supports both OOP and procedural programming.</p>
                    <p>You can use classes for OOP or give straightforward instructions like a to-do list.</p>
                </div>
            </div>
        </section>

        <section class="section">
            <h2>Summary</h2>
            <p>Object-Oriented Programming is a powerful paradigm that helps you:</p>
            <ul>
                <li>Organize code in a logical way</li>
                <li>Reuse code through inheritance</li>
                <li>Protect data through encapsulation</li>
                <li>Create flexible code through polymorphism</li>
                <li>Manage complexity through abstraction</li>
            </ul>
            
            <p>In Python, you implement OOP using:</p>
            <ul>
                <li><strong>Classes</strong> as blueprints</li>
                <li><strong>Objects</strong> as instances of classes</li>
                <li><strong>__init__</strong> as the constructor method</li>
                <li><strong>self</strong> to refer to the current instance</li>
                <li><strong>Methods</strong> to define behaviors</li>
            </ul>
            
            <div class="quote">
                "Objects are like people. They're living, breathing things that have knowledge inside them about how to do things and have memory inside them so they can remember things." - Steve Jobs
            </div>
        </section>

        <footer>
            <p>Interactive OOP Presentation based on the article by Tiago Capelo Monteiro</p>
            <p>Created with HTML, CSS, and JavaScript</p>
        </footer>
    </div>

    <script>
        // Interactive demo functionality
        document.addEventListener('DOMContentLoaded', function() {
            let currentHouse = null;
            const output = document.getElementById('demoOutput');
            
            document.getElementById('createHouse').addEventListener('click', function() {
                const states = ['California', 'Texas', 'Florida', 'New York', 'Colorado'];
                const randomState = states[Math.floor(Math.random() * states.length)];
                const randomPrice = Math.floor(Math.random() * 400000) + 100000;
                const hasAlarm = Math.random() > 0.5;
                
                currentHouse = {
                    address: Math.floor(Math.random() * 9000) + 1000,
                    state: randomState,
                    alarm: hasAlarm,
                    price: randomPrice
                };
                
                output.innerHTML = `
                    <strong>New House Created!</strong><br>
                    Address: ${currentHouse.address}<br>
                    State: ${currentHouse.state}<br>
                    Alarm System: ${currentHouse.alarm ? 'Yes' : 'No'}<br>
                    Price: $${currentHouse.price.toLocaleString()}
                `;
            });
            
            document.getElementById('adjustPrice').addEventListener('click', function() {
                if (!currentHouse) {
                    output.innerHTML = 'Please create a house first!';
                    return;
                }
                
                const inflation = 1.08;
                const oldPrice = currentHouse.price;
                currentHouse.price = Math.round(currentHouse.price * inflation);
                
                output.innerHTML = `
                    <strong>Price Adjusted for Inflation (8%)</strong><br>
                    Address: ${currentHouse.address}<br>
                    State: ${currentHouse.state}<br>
                    Alarm System: ${currentHouse.alarm ? 'Yes' : 'No'}<br>
                    Old Price: $${oldPrice.toLocaleString()}<br>
                    <strong>New Price: $${currentHouse.price.toLocaleString()}</strong>
                `;
            });
            
            document.getElementById('reset').addEventListener('click', function() {
                currentHouse = null;
                output.innerHTML = 'Click "Create a New House" to start';
            });
        });
        
        // Exercise checking functions
        function evaluateCode(code) {
            try {
                // Create a safe evaluation context
                const consoleOutput = [];
                const mockConsole = {
                    log: (...args) => {
                        consoleOutput.push(args.join(' '));
                    },
                    error: (...args) => {
                        consoleOutput.push("ERROR: " + args.join(' '));
                    }
                };
                
                // Create a function with limited scope
                const func = new Function('console', code);
                func(mockConsole);
                
                return {
                    success: true,
                    output: consoleOutput.join('\n')
                };
            } catch (error) {
                return {
                    success: false,
                    output: "Error: " + error.message
                };
            }
        }
        
        // Exercise 1: Creating a simple class
        function checkExercise1() {
            const code = document.getElementById('exercise1-editor').value;
            const outputElement = document.getElementById('exercise1-output');
            
            if (code.trim() === '' || code.includes('pass  # Replace this with your implementation')) {
                outputElement.innerHTML = '<span class="error-message">Please write your code first!</span>';
                return;
            }
            
            const result = evaluateCode(code);
            
            if (result.success) {
                outputElement.innerHTML = `<span class="success-message">Great job! Your code ran successfully.\n\nOutput:\n${result.output}</span>`;
            } else {
                outputElement.innerHTML = `<span class="error-message">${result.output}</span>`;
            }
        }
        
        function resetExercise1() {
            document.getElementById('exercise1-editor').value = `# Write your code here
# 1. Create a Car class with __init__ method
# 2. Add brand, model, and year parameters
# 3. Create an instance of your Car class
# 4. Print the car's details

class Car:
    pass  # Replace this with your implementation

# Create an instance here`;
            document.getElementById('exercise1-output').innerHTML = 'Run your code to see output here...';
        }
        
        // Exercise 2: Using __init__ method
        function checkExercise2() {
            const code = document.getElementById('exercise2-editor').value;
            const outputElement = document.getElementById('exercise2-output');
            
            if (code.trim() === '' || code.includes('pass  # Replace this with your implementation')) {
                outputElement.innerHTML = '<span class="error-message">Please write your code first!</span>';
                return;
            }
            
            const result = evaluateCode(code);
            
            if (result.success) {
                outputElement.innerHTML = `<span class="success-message">Well done! Your code executed correctly.\n\nOutput:\n${result.output}</span>`;
            } else {
                outputElement.innerHTML = `<span class="error-message">${result.output}</span>`;
            }
        }
        
        function resetExercise2() {
            document.getElementById('exercise2-editor').value = `# Write your code here
# 1. Create a Car class with __init__ method
# 2. Initialize brand, model, and year attributes
# 3. Create two instances with different values
# 4. Print details of both cars

class Car:
    pass  # Replace this with your implementation

# Create two instances here`;
            document.getElementById('exercise2-output').innerHTML = 'Run your code to see output here...';
        }
        
        // Exercise 3: Instance vs Class Variables
        function checkExercise3() {
            const code = document.getElementById('exercise3-editor').value;
            const outputElement = document.getElementById('exercise3-output');
            
            if (code.trim() === '' || code.includes('pass  # Replace with your implementation')) {
                outputElement.innerHTML = '<span class="error-message">Please write your code first!</span>';
                return;
            }
            
            const result = evaluateCode(code);
            
            if (result.success) {
                outputElement.innerHTML = `<span class="success-message">Excellent! Your implementation is correct.\n\nOutput:\n${result.output}</span>`;
            } else {
                outputElement.innerHTML = `<span class="error-message">${result.output}</span>`;
            }
        }
        
        function resetExercise3() {
            document.getElementById('exercise3-editor').value = `# Write your code here
# 1. Create a Student class
# 2. Add a class variable school_name = "Tech High"
# 3. Add an __init__ method with name and grade parameters
# 4. Create two student instances
# 5. Print both instance data and the class variable

class Student:
    pass  # Replace with your implementation

# Create instances and print data`;
            document.getElementById('exercise3-output').innerHTML = 'Run your code to see output here...';
        }
        
        // Exercise 4: Creating Methods
        function checkExercise4() {
            const code = document.getElementById('exercise4-editor').value;
            const outputElement = document.getElementById('exercise4-output');
            
            if (code.trim() === '' || code.includes('pass  # Replace with your implementation')) {
                outputElement.innerHTML = '<span class="error-message">Please write your code first!</span>';
                return;
            }
            
            const result = evaluateCode(code);
            
            if (result.success) {
                outputElement.innerHTML = `<span class="success-message">Perfect! Your method works correctly.\n\nOutput:\n${result.output}</span>`;
            } else {
                outputElement.innerHTML = `<span class="error-message">${result.output}</span>`;
            }
        }
        
        function resetExercise4() {
            document.getElementById('exercise4-editor').value = `# Write your code here
# 1. Create a Car class with brand, model, and year attributes
# 2. Add a method get_car_age() that returns the car's age (2025 - year)
# 3. Create an instance and test your method

class Car:
    pass  # Replace with your implementation

# Create instance and test method`;
            document.getElementById('exercise4-output').innerHTML = 'Run your code to see output here...';
        }
        
        // Solution functions
        function showSolution1() {
            document.getElementById('exercise1-editor').value = "# Sample solution for Exercise 1\\n" +
                "class Car:\\n" +
                "    def __init__(self, brand, model, year):\\n" +
                "        self.brand = brand\\n" +
                "        self.model = model\\n" +
                "        self.year = year\\n\\n" +
                "# Create an instance\\n" +
                "my_car = Car(\\"Toyota\\", \\"Camry\\", 2020)\\n" +
                "print(f\\"I have a {my_car.year} {my_car.brand} {my_car.model}\\")";
        }
        
        function showSolution2() {
            document.getElementById('exercise2-editor').value = "# Sample solution for Exercise 2\\n" +
                "class Car:\\n" +
                "    def __init__(self, brand, model, year):\\n" +
                "        self.brand = brand\\n" +
                "        self.model = model\\n" +
                "        self.year = year\\n\\n" +
                "# Create two instances\\n" +
                "car1 = Car(\\"Toyota\\", \\"Camry\\", 2020)\\n" +
                "car2 = Car(\\"Honda\\", \\"Civic\\", 2018)\\n\\n" +
                "print(f\\"Car 1: {car1.year} {car1.brand} {car1.model}\\")\\n" +
                "print(f\\"Car 2: {car2.year} {car2.brand} {car2.model}\\")";
        }
        
        function showSolution3() {
            document.getElementById('exercise3-editor').value = "# Sample solution for Exercise 3\\n" +
                "class Student:\\n" +
                "    school_name = \\"Tech High\\"  # Class variable\\n\\n" +
                "    def __init__(self, name, grade):\\n" +
                "        self.name = name       # Instance variables\\n" +
                "        self.grade = grade\\n\\n" +
                "# Create instances\\n" +
                "student1 = Student(\\"Alice\\", \\"A\\")\\n" +
                "student2 = Student(\\"Bob\\", \\"B\\")\\n\\n" +
                "# Print data\\n" +
                "print(f\\"{student1.name} from {Student.school_name} got grade {student1.grade}\\")\\n" +
                "print(f\\"{student2.name} from {Student.school_name} got grade {student2.grade}\\")";
        }
        
        function showSolution4() {
            document.getElementById('exercise4-editor').value = "# Sample solution for Exercise 4\\n" +
                "class Car:\\n" +
                "    def __init__(self, brand, model, year):\\n" +
                "        self.brand = brand\\n" +
                "        self.model = model\\n" +
                "        self.year = year\\n\\n" +
                "    def get_car_age(self):\\n" +
                "        current_year = 2025\\n" +
                "        return current_year - self.year\\n\\n" +
                "# Create instance and test method\\n" +
                "my_car = Car(\\"Toyota\\", \\"Camry\\", 2020)\\n" +
                "print(f\\"My car is {my_car.get_car_age()} years old\\")";
        }
        
        function resetExercise4() {
            document.getElementById('exercise4-editor').value = `# Write your code here
# 1. Create a Car class with brand, model, and year attributes
# 2. Add a method get_car_age() that returns the car's age (2025 - year)
# 3. Create an instance and test your method

class Car:
    pass  # Replace with your implementation

# Create instance and test method`;
            document.getElementById('exercise4-output').innerHTML = 'Run your code to see output here...';
        }
        
        // Exercise 5: Encapsulation with Bank Account
        // Solution functions
        function showSolution1() {
            document.getElementById('exercise1-editor').value = "# Sample solution for Exercise 1\\n" +
                "class Car:\\n" +
                "    def __init__(self, brand, model, year):\\n" +
                "        self.brand = brand\\n" +
                "        self.model = model\\n" +
                "        self.year = year\\n\\n" +
                "# Create an instance\\n" +
                "my_car = Car(\\"Toyota\\", \\"Camry\\", 2020)\\n" +
                "print(f\\"I have a {my_car.year} {my_car.brand} {my_car.model}\\")";
        }
        
        function showSolution2() {
            document.getElementById('exercise2-editor').value = "# Sample solution for Exercise 2\\n" +
                "class Car:\\n" +
                "    def __init__(self, brand, model, year):\\n" +
                "        self.brand = brand\\n" +
                "        self.model = model\\n" +
                "        self.year = year\\n\\n" +
                "# Create two instances\\n" +
                "car1 = Car(\\"Toyota\\", \\"Camry\\", 2020)\\n" +
                "car2 = Car(\\"Honda\\", \\"Civic\\", 2018)\\n\\n" +
                "print(f\\"Car 1: {car1.year} {car1.brand} {car1.model}\\")\\n" +
                "print(f\\"Car 2: {car2.year} {car2.brand} {car2.model}\\")";
        }
        
        function showSolution3() {
            document.getElementById('exercise3-editor').value = "# Sample solution for Exercise 3\\n" +
                "class Student:\\n" +
                "    school_name = \\"Tech High\\"  # Class variable\\n\\n" +
                "    def __init__(self, name, grade):\\n" +
                "        self.name = name       # Instance variables\\n" +
                "        self.grade = grade\\n\\n" +
                "# Create instances\\n" +
                "student1 = Student(\\"Alice\\", \\"A\\")\\n" +
                "student2 = Student(\\"Bob\\", \\"B\\")\\n\\n" +
                "# Print data\\n" +
                "print(f\\"{student1.name} from {Student.school_name} got grade {student1.grade}\\")\\n" +
                "print(f\\"{student2.name} from {Student.school_name} got grade {student2.grade}\\")";
        }
        
        function showSolution4() {
            document.getElementById('exercise4-editor').value = "# Sample solution for Exercise 4\\n" +
                "class Car:\\n" +
                "    def __init__(self, brand, model, year):\\n" +
                "        self.brand = brand\\n" +
                "        self.model = model\\n" +
                "        self.year = year\\n\\n" +
                "    def get_car_age(self):\\n" +
                "        current_year = 2025\\n" +
                "        return current_year - self.year\\n\\n" +
                "# Create instance and test method\\n" +
                "my_car = Car(\\"Toyota\\", \\"Camry\\", 2020)\\n" +
                "print(f\\"My car is {my_car.get_car_age()} years old\\")";
        }
        
        // Exercise 5: Encapsulation with Bank Account
        function checkExercise5() {
            const code = document.getElementById('exercise5-editor').value;
            const outputElement = document.getElementById('exercise5-output');
            
            if (code.trim() === '' || code.includes('pass  # Replace with your implementation')) {
                outputElement.innerHTML = '<span class="error-message">Please write your code first!</span>';
                return;
            }
            
            const result = evaluateCode(code);
            
            if (result.success) {
                outputElement.innerHTML = `<span class="success-message">Great job! Your encapsulation implementation is working.\\n\\nOutput:\\n${result.output}</span>`;
            } else {
                outputElement.innerHTML = `<span class="error-message">${result.output}</span>`;
            }
        }
        
        function resetExercise5() {
            document.getElementById('exercise5-editor').value = `# Write your code here
# 1. Create a BankAccount class
# 2. Add __init__ method with account_holder parameter
# 3. Add a private __balance attribute, initialized to 0
# 4. Add deposit(amount) method to add to balance
# 5. Add withdraw(amount) method to subtract from balance (if sufficient funds)
# 6. Add get_balance() method to return current balance
# 7. Test your class with some transactions

class BankAccount:
    pass  # Replace with your implementation

# Test your implementation`;
            document.getElementById('exercise5-output').innerHTML = 'Run your code to see output here...';
        }
        
        // Exercise 6: Inheritance with Animals
        function checkExercise6() {
            const code = document.getElementById('exercise6-editor').value;
            const outputElement = document.getElementById('exercise6-output');
            
            if (code.trim() === '' || code.includes('pass  # Replace with your implementation')) {
                outputElement.innerHTML = '<span class="error-message">Please write your code first!</span>';
                return;
            }
            
            const result = evaluateCode(code);
            
            if (result.success) {
                outputElement.innerHTML = `<span class="success-message">Excellent! Your inheritance implementation is correct.\\n\\nOutput:\\n${result.output}</span>`;
            } else {
                outputElement.innerHTML = `<span class="error-message">${result.output}</span>`;
            }
        }
        
        function resetExercise6() {
            document.getElementById('exercise6-editor').value = `# Write your code here
# 1. Create an Animal class with name and species attributes
# 2. Add a make_sound() method that prints a generic sound
# 3. Create Dog and Cat classes that inherit from Animal
# 4. Override make_sound() in each subclass to make animal-specific sounds
# 5. Add breed attribute to Dog and color attribute to Cat
# 6. Test your classes

class Animal:
    pass  # Replace with your implementation

class Dog:
    pass  # Replace with your implementation

class Cat:
    pass  # Replace with your implementation

# Test your implementation`;
            document.getElementById('exercise6-output').innerHTML = 'Run your code to see output here...';
        }
        
        // Exercise 7: Polymorphism with Shapes
        function checkExercise7() {
            const code = document.getElementById('exercise7-editor').value;
            const outputElement = document.getElementById('exercise7-output');
            
            if (code.trim() === '' || code.includes('pass  # Replace with your implementation')) {
                outputElement.innerHTML = '<span class="error-message">Please write your code first!</span>';
                return;
            }
            
            const result = evaluateCode(code);
            
            if (result.success) {
                outputElement.innerHTML = `<span class="success-message">Perfect! Your polymorphism implementation works correctly.\\n\\nOutput:\\n${result.output}</span>`;
            } else {
                outputElement.innerHTML = `<span class="error-message">${result.output}</span>`;
            }
        }
        
        function resetExercise7() {
            document.getElementById('exercise7-editor').value = `# Write your code here
# 1. Create a Shape class with an area() method that returns 0
# 2. Create Circle and Rectangle classes that inherit from Shape
# 3. Override area() in each subclass with appropriate calculations
# 4. Add necessary attributes in __init__ methods (radius for Circle, width/height for Rectangle)
# 5. Test your classes

class Shape:
    pass  # Replace with your implementation

class Circle:
    pass  # Replace with your implementation

class Rectangle:
    pass  # Replace with your implementation

# Test your implementation`;
            document.getElementById('exercise7-output').innerHTML = 'Run your code to see output here...';
        }
        
        // Exercise 8: Method Overriding
        function checkExercise8() {
            const code = document.getElementById('exercise8-editor').value;
            const outputElement = document.getElementById('exercise8-output');
            
            if (code.trim() === '' || code.includes('pass  # Replace with your implementation')) {
                outputElement.innerHTML = '<span class="error-message">Please write your code first!</span>';
                return;
            }
            
            const result = evaluateCode(code);
            
            if (result.success) {
                outputElement.innerHTML = `<span class="success-message">Well done! Your method overriding implementation is correct.\\n\\nOutput:\\n${result.output}</span>`;
            } else {
                outputElement.innerHTML = `<span class="error-message">${result.output}</span>`;
            }
        }
        
        function resetExercise8() {
            document.getElementById('exercise8-editor').value = `# Write your code here
# 1. Create a Vehicle class with start_engine() method that prints "Vehicle engine started"
# 2. Create a Car class that inherits from Vehicle
# 3. Override start_engine() in Car to print "Car engine started"
# 4. Add a call to super().start_engine() in the Car's start_engine method
# 5. Test both classes

class Vehicle:
    pass  # Replace with your implementation

class Car:
    pass  # Replace with your implementation

# Test your implementation`;
            document.getElementById('exercise8-output').innerHTML = 'Run your code to see output here...';
        }
        
        // Solution functions for new exercises
        function showSolution5() {
            document.getElementById('exercise5-editor').value = "# Sample solution for Exercise 5\\n" +
                "class BankAccount:\\n" +
                "    def __init__(self, account_holder):\\n" +
                "        self.account_holder = account_holder\\n" +
                "        self.__balance = 0  # Private attribute\\n\\n" +
                "    def deposit(self, amount):\\n" +
                "        if amount > 0:\\n" +
                "            self.__balance += amount\\n" +
                "            print(f\\"Deposited ${amount}. New balance: ${self.__balance}\\")\\n" +
                "        else:\\n" +
                "            print(\\"Deposit amount must be positive\\")\\n\\n" +
                "    def withdraw(self, amount):\\n" +
                "        if amount > 0 and amount <= self.__balance:\\n" +
                "            self.__balance -= amount\\n" +
                "            print(f\\"Withdrew ${amount}. New balance: ${self.__balance}\\")\\n" +
                "        else:\\n" +
                "            print(\\"Invalid withdrawal amount\\")\\n\\n" +
                "    def get_balance(self):\\n" +
                "        return self.__balance\\n\\n" +
                "# Test the implementation\\n" +
                "account = BankAccount(\\"John Doe\\")\\n" +
                "account.deposit(100)\\n" +
                "account.withdraw(50)\\n" +
                "print(f\\"Final balance: ${account.get_balance()}\\")";
        }
        
        function showSolution6() {
            document.getElementById('exercise6-editor').value = "# Sample solution for Exercise 6\\n" +
                "class Animal:\\n" +
                "    def __init__(self, name, species):\\n" +
                "        self.name = name\\n" +
                "        self.species = species\\n\\n" +
                "    def make_sound(self):\\n" +
                "        print(\\"Some generic animal sound\\")\\n\\n" +
                "class Dog(Animal):\\n" +
                "    def __init__(self, name, breed):\\n" +
                "        super().__init__(name, \\"Dog\\")\\n" +
                "        self.breed = breed\\n\\n" +
                "    def make_sound(self):\\n" +
                "        print(\\"Woof! Woof!\\")\\n\\n" +
                "class Cat(Animal):\\n" +
                "    def __init__(self, name, color):\\n" +
                "        super().__init__(name, \\"Cat\\")\\n" +
                "        self.color = color\\n\\n" +
                "    def make_sound(self):\\n" +
                "        print(\\"Meow!\\")\\n\\n" +
                "# Test the implementation\\n" +
                "dog = Dog(\\"Buddy\\", \\"Golden Retriever\\")\\n" +
                "cat = Cat(\\"Whiskers\\", \\"Orange\\")\\n\\n" +
                "print(f\\"{dog.name} is a {dog.breed} {dog.species}\\")\\n" +
                "dog.make_sound()\\n\\n" +
                "print(f\\"{cat.name} is a {cat.color} {cat.species}\\")\\n" +
                "cat.make_sound()";
        }
        
        function showSolution7() {
            document.getElementById('exercise7-editor').value = "# Sample solution for Exercise 7\\n" +
                "import math\\n\\n" +
                "class Shape:\\n" +
                "    def area(self):\\n" +
                "        return 0\\n\\n" +
                "class Circle(Shape):\\n" +
                "    def __init__(self, radius):\\n" +
                "        self.radius = radius\\n\\n" +
                "    def area(self):\\n" +
                "        return math.pi * self.radius ** 2\\n\\n" +
                "class Rectangle(Shape):\\n" +
                "    def __init__(self, width, height):\\n" +
                "        self.width = width\\n" +
                "        self.height = height\\n\\n" +
                "    def area(self):\\n" +
                "        return self.width * self.height\\n\\n" +
                "# Test the implementation\\n" +
                "circle = Circle(5)\\n" +
                "rectangle = Rectangle(4, 6)\\n\\n" +
                "print(f\\"Circle area: {circle.area():.2f}\\")\\n" +
                "print(f\\"Rectangle area: {rectangle.area()}\\")";
        }
        
        function showSolution8() {
            document.getElementById('exercise8-editor').value = "# Sample solution for Exercise 8\\n" +
                "class Vehicle:\\n" +
                "    def start_engine(self):\\n" +
                "        print(\\"Vehicle engine started\\")\\n\\n" +
                "class Car(Vehicle):\\n" +
                "    def start_engine(self):\\n" +
                "        print(\\"Car engine started\\")\\n" +
                "        super().start_engine()  # Call parent method\\n\\n" +
                "# Test the implementation\\n" +
                "vehicle = Vehicle()\\n" +
                "car = Car()\\n\\n" +
                "print(\\"Starting vehicle engine:\\")\\n" +
                "vehicle.start_engine()\\n\\n" +
                "print(\\"Starting car engine:\\")\\n" +
                "car.start_engine()";
        }
        
    </script>
</body>
</html>