Visibility control in Ruby (public, private, and protected)

Public (Public Methods)

class MyClass
  def public_method_name
    # This method is public by default
  end

  public :public_method_name  # Explicitly declaring it as public, but it's not necessary
end

class MyClass
  def public_method_name
    # This method is public by default
  end
end

Private (Private Methods)

class MyClass
  private # all methods that follow this line are private

  def private_method_name
    # This method is private
  end
end

Protected (Protected Methods)

class MyClass
  protected # all methods that follow this line are protected

  def protected_method
    # This method is protected
  end
end

Exercise to Learn Public, Private, and Protected Methods

• Create a User class with the following properties: name and age.
• All properties should be private.

• Add a greet method that outputs the message: "Hello, how are you?"
• Add an access_age method that returns the user's age.

• Make the greet method public.
• Make the access_age method protected.

• Create a subclass Admin that inherits from the User class.

• Create an object of the User class and an object of the Admin class.
• Call the greet method on the objects of both classes.
• Try to access the age using the access_age method on the User class object and try the same on the Admin class object.

• Note which methods you successfully called and which resulted in an error.
• Determine which methods can be called from outside the class and which cannot.

• Organize the code
• Change method names to more understandable ones (access_age -> age)

class User
  def initialize(name, age)
    @name = name
    @age = age
  end

  def greet
    puts "Hello, how are you?"
  end

  def access_age
    @age
  end

  private

  def private_method
    puts "This is a private method"
  end

  protected

  def protected_method
    puts "This is a protected method"
  end
end

class Admin < User
  # Admin inherits all properties and methods from User
end

# Creating objects
user = User.new("User", 25)
admin = Admin.new("Admin", 30)

# Calling the public method
user.greet
admin.greet

# Trying to call the protected method
# user.protected_method  # Will result in an error

# Trying to call the private method
# user.private_method  # Will result in an error

# Output age
puts "User's age: #{user.access_age}"
puts "Admin's age: #{admin.access_age}"