Ruby dynamically resolve names from a hash

methodmissinghash.rb

def respond_to? method_sym, include_private = false
  if @a.has_key? method_sym
    true
  else
    super method_sym, include_private
  end
end

def method_missing method_sym, *arguments, &block
  if @a.has_key? method_sym
    @a[method_sym]
  else
    super method_sym, *arguments, &block
  end
end