Instance Method

Creating an object, and calling instance method#

class Mail
  def self.send_message(message:)
    puts message
  end
    
  def second_send(message:)
    puts message
  end
end

mail = Mail.new
mail.second_send(message: "this is a test second message.")

# output:
$ruby main.rb
this is a test second message.

Class method cannot be called via the object:#

class Mail
    def self.send_message(message:)
        puts message
    end
    
    def second_send(message:)
        puts message
    end
    
end

mail = Mail.new
mail.send_message(message: "this is a test second message.")

# output:
$ruby main.rb
main.rb:13:in `<main>': undefined method `send_message' for #<Mail:0x0055c9ed73e008> (NoMethodError)