# metaprogramming to the rescue!

class Numeric
  @@currencies = {'yen' => 0.013, 'euro' => 1.292, 'rupee' => 0.019, 'auksinas' => 10.09 }
  def method_missing(method_id, *args, &block)  # capture all args in case have to call super
    singular_currency = method_id.to_s.gsub( /s$/, '')
    singular_currency_s = method_id.to_s.gsub( /es$/, '')
    if @@currencies.has_key?(method_id)
      self * @@currencies[method_id]
    elsif @@currencies.has_key?(singular_currency)
      self * @@currencies[singular_currency]
    elsif @@currencies.has_key?(singular_currency_s)
      self * @@currencies[singular_currency_s]
    else
      super
    end
  end
end