# Init option `helptext`, `default_value` and `names`.
	#
	# Also set current `value` to `default`.
	fun init_opt(help: String, default: VALUE, names: nullable Array[String])
	do
		if names == null then
			self.names = new Array[String]
		else
			self.names = names.to_a
		end
		helptext = help
		default_value = default
		value = default
	end