Bit of a wordy title but it is as it sounds. Allow the ability to pass in arguments to a listener from the main scope without the usage of upvaluing. Something like this:
local function Listener(EventArg, Arg2) -- Do something with this. end local Arg2 = "Arg2" engine:on("event", Listener, Arg2) --Arg2 would be passed to Listener as the second argument. The first would be whatever the connection passes.
Makes sense right?