/datum
	var/gc_destroyed //Time when this object was destroyed.
	var/list/active_timers  //for SStimer
	var/list/datum_components //for /datum/components
	var/list/status_traits
	var/list/comp_lookup //it used to be for looking up components which had registered a signal but now anything can register
	var/list/signal_procs
	var/signal_enabled = FALSE
	var/datum_flags = NONE
	var/datum/weakref/weak_reference

#ifdef TESTING
	var/running_find_references
	var/last_find_references = 0
#endif

#ifdef DATUMVAR_DEBUGGING_MODE
	var/list/cached_vars
#endif

// Default implementation of clean-up code.
// This should be overridden to remove all references pointing to the object being destroyed.
// Return the appropriate QDEL_HINT; in most cases this is QDEL_HINT_QUEUE.
/datum/proc/Destroy(force=FALSE, ...)
	tag = null
	datum_flags &= ~DF_USE_TAG //In case something tries to REF us
	weak_reference = null	//ensure prompt GCing of weakref.

	var/list/timers = active_timers
	active_timers = null
	for(var/thing in timers)
		var/datum/timedevent/timer = thing
		if (timer.spent)
			continue
		qdel(timer)

	//BEGIN: ECS SHIT
	signal_enabled = FALSE

	var/list/dc = datum_components
	if(dc)
		var/all_components = dc[/datum/component]
		if(length(all_components))
			for(var/I in all_components)
				var/datum/component/C = I
				qdel(C, FALSE, TRUE)
		else
			var/datum/component/C = all_components
			qdel(C, FALSE, TRUE)
		dc.Cut()

	var/list/lookup = comp_lookup
	if(lookup)
		for(var/sig in lookup)
			var/list/comps = lookup[sig]
			if(length(comps))
				for(var/i in comps)
					var/datum/component/comp = i
					comp.UnregisterSignal(src, sig)
			else
				var/datum/component/comp = comps
				comp.UnregisterSignal(src, sig)
		comp_lookup = lookup = null

	for(var/target in signal_procs)
		UnregisterSignal(target, signal_procs[target])
	//END: ECS SHIT

	return QDEL_HINT_QUEUE

#ifdef DATUMVAR_DEBUGGING_MODE
/datum/proc/save_vars()
	cached_vars = list()
	for(var/i in vars)
		if(i == "cached_vars")
			continue
		cached_vars[i] = vars[i]

/datum/proc/check_changed_vars()
	. = list()
	for(var/i in vars)
		if(i == "cached_vars")
			continue
		if(cached_vars[i] != vars[i])
			.[i] = list(cached_vars[i], vars[i])

/datum/proc/txt_changed_vars()
	var/list/l = check_changed_vars()
	var/t = "[src]([REF(src)]) changed vars:"
	for(var/i in l)
		t += "\"[i]\" \[[l[i][1]]\] --> \[[l[i][2]]\] "
	t += "."

/datum/proc/to_chat_check_changed_vars(target = world)
	to_chat(target, txt_changed_vars())
#endif

//Return a LIST for serialize_datum to encode! Not the actual json!
/datum/proc/serialize_list(list/options)
	CRASH("Attempted to serialize datum [src] of type [type] without serialize_list being implemented!")

//Accepts a LIST from deserialize_datum. Should return src or another datum.
/datum/proc/deserialize_list(json, list/options)
	CRASH("Attempted to deserialize datum [src] of type [type] without deserialize_list being implemented!")

//Serializes into JSON. Does not encode type.
/datum/proc/serialize_json(list/options)
	. = serialize_list(options)
	if(!islist(.))
		. = null
	else
		. = json_encode(.)

//Deserializes from JSON. Does not parse type.
/datum/proc/deserialize_json(list/input, list/options)
	var/list/jsonlist = json_decode(input)
	. = deserialize_list(jsonlist)
	if(!istype(., /datum))
		. = null

/proc/json_serialize_datum(datum/D, list/options)
	if(!istype(D))
		return
	var/list/jsonlist = D.serialize_list(options)
	if(islist(jsonlist))
		jsonlist["DATUM_TYPE"] = D.type
	return json_encode(jsonlist)

/proc/json_deserialize_datum(list/jsonlist, list/options, target_type, strict_target_type = FALSE)
	if(!islist(jsonlist))
		if(!istext(jsonlist))
			CRASH("Invalid JSON")
			return
		jsonlist = json_decode(jsonlist)
		if(!islist(jsonlist))
			CRASH("Invalid JSON")
			return
	if(!jsonlist["DATUM_TYPE"])
		return
	if(!ispath(jsonlist["DATUM_TYPE"]))
		if(!istext(jsonlist["DATUM_TYPE"]))
			return
		jsonlist["DATUM_TYPE"] = text2path(jsonlist["DATUM_TYPE"])
		if(!ispath(jsonlist["DATUM_TYPE"]))
			return
	if(target_type)
		if(!ispath(target_type))
			return
		if(strict_target_type)
			if(target_type != jsonlist["DATUM_TYPE"])
				return
		else if(!ispath(jsonlist["DATUM_TYPE"], target_type))
			return
	var/typeofdatum = jsonlist["DATUM_TYPE"]			//BYOND won't directly read if this is just put in the line below, and will instead runtime because it thinks you're trying to make a new list?
	var/datum/D = new typeofdatum
	var/datum/returned = D.deserialize_list(jsonlist, options)
	if(!istype(returned, /datum))
		qdel(D)
	else
		return returned