Learn Ruby Metaprogramming for Great Good

[caption id="attachment_141384" align="alignnone" width="1912"] Ruby Metaprogramming can be a good thing.[/caption]

Recently, I was reviewing one of my student's code. He had a program with many methods that printed out various messages, for example:

class MyClass
  def calculate(a)
    result = a ** 2
    puts "The result is #{result}"
  end
end

class MyOtherClass
  def some_action(a, b)
    puts "The first value is #{a}, the second is #{b}"
  end

  def greet
    puts "Welcome!"
  end
end

I suggested that he store these messages in a separate file to simplify the process working with them. Then, I remembered how I18n translations are stored in Rails and got an idea. Why don't we create a YAML file (a so-called dictionary) with all the messages and a helper method to fetch them properly, all while supporting additional features like interpolation? This is totally possible with Ruby's metaprogramming!

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by Ilya Bodrov-Krukowski via SitePoint