The case for named arguments in Ruby

gistfile1.rb

# Usage:
#
# def foo(opts = {})
#  opts.require_keys!(:bar)
#  puts 'yay'
# end
#
# foo()
# => MissingRequiredHashKeyError: Hash key ':bar' missing
#
# foo(:bar)
# => yay

class MissingRequiredHashKeyError < StandardError; end

class Hash
  def require_keys!(*required_keys)
    required_keys.flatten.each do |required_key|
      if !self.keys.include?(required_key)
        key_string = (required_key.is_a?(Symbol) ? ":#{required_key}" : required_key )
        raise MissingRequiredHashKeyError, "Hash key '#{key_string}' missing"
      end
    end
    true
  end
end