Unintuitive scripting behavior: source variable in Lua becomes nil if any time passes during event handler

[Lucas7yoshi]

When a server event handler is being run, the source variable thats inherently provided becomes nil if any time passes i.e Wait()'ing

This is confusing behavior and presumably not intended

it can be worked around by simply defining a second variable and setting it to the value of source at the beginning but is obviously not ideal

Repro code:

CLIENT:

RegisterCommand("sourcerepro", function(source, args, raw)
    TriggerServerEvent("reproevent")
end)

SERVER:

RegisterNetEvent("reproevent")
AddEventHandler("reproevent", function()
    print(source)
    Wait(0)
    print(source)
end)

[maicek]

It's not bug, the source variable is defined in scheduler.lua as global variable

fivem/data/shared/citizen/scripting/lua/scheduler.lua

Lines 156 to 159 in 71a593b

	Citizen.SetEventRoutine(function(eventName, eventPayload, eventSource)
	-- set the event source
	local lastSource = _G.source
	_G.source = eventSource

So, you can simply use:

local src = source

at top of event handler to use event source after wait

[Lucas7yoshi]

It's not bug, the source variable is defined in scheduler.lua as global variable

fivem/data/shared/citizen/scripting/lua/scheduler.lua

Lines 156 to 159 in 71a593b

	Citizen.SetEventRoutine(function(eventName, eventPayload, eventSource)
	-- set the event source
	local lastSource = _G.source
	_G.source = eventSource

So, you can simply use:

local src = source

at top of event handler to use event source after wait

Noted, i figured this was some weird behavior but seeing how that works now makes sense and any alternative would not be within the realm of easy fixing. Closing

[blattersturm]

This is still somewhat illogical behavior, but somehow dynamically adding upvalues for a handler sounds like a potential mess (and requiring the lexer/parser to be aware of this beforehand, even).

A similar alternative could be something like the .NET SynchronizationContext where state like 'source' is saved and restored when yielding with such set.