Classes in Ruby

Classes do not have to be in a separate file as you can see from the file below.

Let’s look at a class, then break it down.

class Student
  # Class variable to keep track of the total number of students
  @@total_students = 0

  # Constructor method (called when a new object is created)
  def initialize(name, age, grade)
    @name = name      # Instance variable for the student's name
    @gpa = gpa        # Instance variable for the student's gpa
    @major = major    # Instance variable for the student's major
    @@total_students += 1
  end

  # Method to display student details
  def display_info
    puts "Name: #{@name}"
    puts "GPA: #{@gpa}"
    puts "Major: #{@major}"
  end

  # Class method to access the total number of students
  def self.total_students
    @@total_students
  end
end

# Example usage:
student1 = Student.new("Alice", 3.25, "Business")
student2 = Student.new("Bob", 3.4, "Computer Science")

student1.display_info
student2.display_info

puts "Total students: #{Student.total_students}"

Class Definition

As with most languages, you use class to define your class definition, and class names typically start with a capital letter.

As with conditions, and other blocks, the class definition ends with end. This can be a little confusing since there are multiple ends associated with the internal methods. Therefore one might consider using a comment at the end of each end, to clearly delineate what it is in reference to.

Class Variables

Class level variables, if they exist in the class, are typically defined at the top of the class, shortly after defining the class.

  # Class variable to keep track of the total number of students
  @@total_students = 0

Constructor

Notice that you have a constructor, unlike Go. However, each language defines a constructor differently. Where Python uses init and C/C++ and Java use the class name, Ruby uses initialize. Like with Python, you use the def keyword to define a method name, including the constructor.

  # Constructor method (called when a new object is created)
  def initialize(name, gpa, major)
    @name = name      # Instance variable for the student's name
    @gpa = gpa        # Instance variable for the student's gpa
    @major = major    # Instance variable for the student's grade
    @@total_students += 1
  end

Not only do we define the constructor, but also the class properties.

Methods

Class methods are after the constructor. A def keyword is used to define them. Otherwise they are similar to any other function definition.

Classes in Ruby was originally found on Access 2 Learn