require 'YAML'

# Retains as a constant
CONFIG = YAML.load_file('config.yml')

# or
# Retains as an instance variable.

class Config
  def initialize(name)
    @config = get_from_disk(name)
  end

  def get
    @config
  end
private
  def get_from_disk(name)
   YAML.load_file(name)
  end
end

config = Config.new('config.yml')
config.get