Datum Component System (DCS)
Loosely adapted from /vg/. This is an entity component system for adding behaviours to datums when inheritance doesn't quite cut it. By using signals and events instead of direct inheritance, you can inject behaviours without hacky overloads. It requires a different method of thinking, but is not hard to use correctly. If a behaviour can have application across more than one thing. Make it generic, make it a component. Atom/mob/obj event? Give it a signal, and forward it's arguments with a
See this thread for an introduction to the system as a whole.
See/Define signals and their arguments in __DEFINES\dcs\signals.dm