maid library

Classes

ControllerMaid<Box>: ControllerMaid wrap a _box and holding it. Provide a controller-like interface.
Maids
SingletonMaid: SingletonMaid.of with type parameter can easily create a VowedControllerMaid with singleton behavior. Which means you can not replace the box that Maid holding with another one.
VowedControllerMaid<Box>: A VowedControllerMaid is a ControllerMaid that vow to secure the box forever. The box will never be take by another box. Any trying will result a BreakingVowException without actually works.