Cpp1_9.html

<article>
    <h1>C++ I: Page 9 - OOP: Inheritance & Polymorphism</h1>

    <section>
        <h2>Reusability and Dynamic Dispatch</h2>
        <p>Inheritance allows you to create specialized classes from general ones, while Polymorphism (via <code>virtual</code> functions) allows you to treat different types through a common interface.</p>
        
        <h3>The Code implementation</h3>
        <pre><code class="language-cpp">
/*
 * File: inheritance.cpp
 * Demonstration of polymorphism, virtual functions, and final keyword
 */
#include &lt;iostream&gt;
#include &lt;vector&gt;
#include &lt;string&gt;

using namespace std;

// Base class
class Animal {
public:
    // Virtual destructor is crucial for base classes
    virtual ~Animal() { cout << "Animal destructor" << endl; }

    // Virtual function enables polymorphism
    virtual void speak() const {
        cout << "Some animal sound" << endl;
    }
};

// Derived class: final prevents further inheritance
class Dog final : public Animal {
public:
    void speak() const override { // Explicit override
        cout << "Woof!" << endl;
    }
};

// Derived class
class Cat : public Animal {
public:
    void speak() const override {
        cout << "Meow!" << endl;
    }
};

int main() {
    // Dynamic dispatch using pointers to base class
    vector&lt;Animal*&gt; zoo;
    zoo.push_back(new Dog());
    zoo.push_back(new Cat());

    cout << "--- Polymorphism in action ---" << endl;
    for (const auto& animal : zoo) {
        animal->speak(); // Correct version called at runtime
    }

    // Cleanup
    for (auto animal : zoo) {
        delete animal;
    }

    return 0;
}

/*
 * OOP Nuances:
 * 1. Virtual destructor: Ensures proper cleanup of derived objects 
 *    when deleted via base pointer.
 * 2. 'virtual' keyword: Instructs compiler to use dynamic dispatch (vtable).
 * 3. 'override': Strongly recommended to catch errors in signature mismatch.
 * 4. 'final': Prevents further derivation of a class or overriding of a method.
 * 5. Polymorphism enables flexible, extensible code architectures.
 * 6. Slicing: Be careful not to pass objects by value when polymorphism
 *    is expected; always use pointers or references.
 */
        </code></pre>
            <button class="sim-button" onclick="
                const out = document.getElementById('sim-output-cpp1_9');
                out.innerHTML = 'Animal* a = new Dog();<br>';
                setTimeout(() => out.innerHTML += '>> a->speak() calls Dog::speak()', 800);
            ">Run Simulation</button>
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