That would be nice

config.as-is.rb

# what if…

class Config
  def initialize(path)
    @data = YAML.parse_file(path)
  end

  protected
  def root_path
    @root_path ||= @data['app']['root_path']
  end
end

config.nice.rb

# … could be written like this

class Config
  # "incoming" filters. Used when writing that attribute
  @data << YAML.parse_file

  # "outgoing" filters. Used when reading that attribute
  @root_path >> @data['app']['base_path']
  
  # Also: No extra lambda/Proc notation

  # One line method definitions
  def initialize(@data = path)
end