Add code to support cancelling jobs

mods/CORE/vl_scheduler/init.lua

@@ -220,20 +220,34 @@ local function queue_task(when, priority, task)
 end
 vl_scheduler.queue_task = queue_task
 
+local task_metatable = {
+	__index = {
+		cancel = function(self)
+			self.real_func = function() end
+		end,
+		func = function(self)
+			self.real_func(unpack(self.args))
+		end,
+	}
+}
+
 local function vl_scheduler_after(time, priority, func, ...)
 	local task = new_task()
 	task.args = {...}
 	task.next = nil
 	task.real_func = func
-	task.func = function(task) task.real_func(unpack(task.args)) end
+	setmetatable(task, task_metatable)
 	local timesteps = math.round(time / 0.05)
 	queue_task(timesteps, priority, task)
+
+	-- Return a job handle that can cancel
+	return task
 end
 vl_scheduler.after = vl_scheduler_after
 
 -- Hijack core.after and redirect to this scheduler
 function core.after(time, func, ...)
-	vl_scheduler_after(time, 2, func, ...)
+	return vl_scheduler_after(time, 2, func, ...)
 end
 
 return vl_scheduler

mods/CORE/vl_scheduler/unit-test.lua

@@ -201,5 +201,18 @@ describe('vl_scheduler',function()
 			call_globalstep(0.05)
 		end)
 	end)
+	it('can provide cancellable jobs from core.after()',function()
+		local after = _G.core.after
+		local ran = false
+		local job = after(1,function()
+			ran = true
+		end)
+		call_globalstep(0.5)
+		assert.no_error(function()
+			job:cancel()
+		end)
+		for i = 1,10 do call_globalstep(0.5) end
+		assert.is_false(ran)
+	end)
 end)