Refactor example (Before / After) for Predicate method magic in a class I made for the link_shrink gem.

predicate_magic.rb

# Old:
module LinkShrink
  class Options < Hash
    def initialize(*args)
      super(*args)
      self.merge!(self.default)
    end
    
    def qr_code?
      self.fetch(:qr_code, false)
    end
    
    def json?
      self.fetch(:json, false)
    end
    
    def image_size?
      self.fetch(:image_size, '150x150')
    end
  end
end

# Refactor:

module LinkShrink
  class Options < Hash
    def initialize(*args)
      super(*args)
      self.merge!(self.default)
    end

    returns = { qr_code: false, json: false, image_size: '150x150' }

    returns.map do |method, default_value|
      define_method "#{method}?" do
        self.fetch(method, default_value)
      end
    end
  end
end