classes_in_ruby.md

In Ruby, you define a class like this:

class Dog

end

You build an instance of a Dog class like this:

rufus = Dog.new

You can add a method for Dog class, this method will be available for all instances of Dog you have been created

class Dog
  def bark
    puts 'Ruff! Ruff!' 
  end
end

Now, Rufus can bark

rufus.bark  #Ruff! Ruff!

But if I would to know how old is Rufus, I can create an atribute @age and implement a constructor method to set his age, by default this methis is called initialize

class Dog

  def initialize(age)
     @age = age
  end
  
  def bark
    puts 'Ruff! Ruff!' 
  end
  
  def how_old_are_you?
    return "I'm #{age} years old"
  end
  
end

And you can ask for his age like this

rufus = Dog.new(4)
rufus.how_old_are_you? # I'm 4 year old