**Course Title:** Ruby Programming: From Basics to Advanced Techniques **Section Title:** Object-Oriented Programming (OOP) in Ruby **Topic:** Introduction to classes and objects. **Introduction to Classes and Objects** ===================================== In this topic, we will introduce the fundamental concepts of Object-Oriented Programming (OOP) in Ruby, focusing on classes and objects. You will learn how to define and use classes to create objects, and understand the benefits of OOP in programming. **What are Classes and Objects?** ------------------------------- In OOP, a **class** is a blueprint or a template that defines the properties and behavior of an object. A **class** is essentially a design pattern or a template that defines the characteristics of an object. An **object**, on the other hand, is an instance of a class, and represents a real-world entity or concept. **Defining a Class in Ruby** ------------------------- In Ruby, a class is defined using the `class` keyword followed by the name of the class. The class definition is enclosed within the `class` and `end` keywords. ```ruby class MyClass # class definition end ``` **Class Name Convention** --------------------- In Ruby, class names should start with a capital letter and use CamelCase convention. **Creating an Object** --------------------- To create an object from a class, we use the `new` method. ```ruby class MyClass # class definition end my_object = MyClass.new ``` **Attributes and Instance Variables** ---------------------------------- In Ruby, attributes are represented by instance variables, which are variables defined inside a class. To create an instance variable, we use the `@` symbol followed by the name of the variable. ```ruby class MyClass def initialize(name) @name = name end end my_object = MyClass.new('John Doe') ``` In this example, `@name` is an instance variable that stores the name of the object. **Methods** --------- Methods are functions that belong to a class or object. In Ruby, methods are defined using the `def` keyword followed by the name of the method. ```ruby class MyClass def greet puts "Hello, my name is #{@name}." end end my_object = MyClass.new('John Doe') my_object.greet # Output: Hello, my name is John Doe. ``` In this example, `greet` is a method that belongs to the `MyClass` class. **Key Concepts** ---------------- * **Inheritance**: classes can inherit behavior from other classes. * **Polymorphism**: objects of different classes can respond to the same method name. * **Encapsulation**: objects hide their internal state and expose only necessary information through methods. **Best Practices** ----------------- * Use meaningful class and method names. * Keep classes and methods concise and focused on a single responsibility. * Use instance variables to store object state. **Conclusion** ---------- In this topic, we introduced the fundamental concepts of classes and objects in Ruby. We learned how to define classes, create objects, and use methods to interact with objects. Understanding classes and objects is crucial for building robust and maintainable software systems. **What's Next?** -------------- In the next topic, we will explore how to use attributes and methods to create getter and setter methods in Ruby. Do you have questions about classes and objects in Ruby? Please leave a comment below. Recommended Resources: * [Ruby Documentation on Classes and Objects](https://ruby-doc.org/core-2.7.1/Class.html) * [Codecademy's Ruby Course on Classes and Objects](https://www.codecademy.com/learn/learn-ruby/modules/learn-ruby-classes) Please ask if you have any questions after reading this tutorial.