How to integrate metaprogramming techniques into a custom class

Now that you have gone through the Metaprogramming introduction section, let's see how to integrate it into a custom class in Ruby.

To start, let's create an empty Baseball class:

class Baseball
end 

Now, we instantiate it and call a method using the following code:

p Baseball.new.swing 

You'll get an error, and this is good because we don't have a method called swing in the Baseball class.

In a later lesson, we'll walk through the process of creating methods on the fly, but right now, let's simply open the Baseball class and add the method manually:

class Baseball
end

class Baseball
  def swing
    "Homerun"
  end
end

p Baseball.new.swing 

If you run this program, it will return the "Homerun" message. This example shows the flexibility that Ruby offers when you want to reopen a class and make changes to it. Since this is a basic example, it doesn't make much of a difference. But if you have to do this in a large Ruby program with...