Lua Arguments and Numbers - lua

Question

function OnChat(PlayerId, Type, Message)
if Message == "!usecarepackage" then
if ReadKS1 == "CP" or ReadKS2 == "CP" or ReadKS3 == "CP" then
InputConsole("msg %s has requested a care package!", Get_Player_Name_By_ID(pID))
local pos = Get_Position(Get_GameObj(pID))
pos:AssignY(pos:GetY()+1)
building = Create_Object("SignalFlare_Gold_Phys3", pos)
Attach_Script(building, "Test_Cinematic", "caredrop.txt")
if building == nil then
InputConsole("ppage %d Cannot spawn Care Package here.", pID)
elseif math.random(50, 64) == 50 then
Attach_Script(building, "z_Set_Team", Get_Team(pID))
Attach_Script(building, "M00_No_Falling_Damage_DME")
--Add in rest of numbers and corresponding streak, such as UAV if math.random = 50
end
elseif ReadKS1 ~= "CP" or ReadKS2 ~= "CP" or ReadKS3 ~= "CP" then
InputConsole("ppage %d You are not allowed to use that with your current streak selection", pID)
end
end
return 1
end
I know this is scruffy code, but I'm receiving a "Bad argument #2 to 'format' (number expected, got no value)". This relates to this piece of code which prefixes all other pieces:
function InputConsole(...)
Console_Input(string.format(unpack(arg)))
end
Finally, this is for the game Command and Conquer Renegade (should you wish to look up API etc). Any help in what I'm doing wrong would be much appreciated.

Answer 1

The likely problem with this code is the use of the deprecated arg feature in your function InputConsole(). Lua 5.0 used arg as a way to access the actual arguments to a function declared as variadic using the ... token in the argument list.
Edit: But likely doesn't mean correct.
The actual problem looks like the switch in idiom from PlayerId to pID. The former is the named parameter of the function OnChat(), while the latter is a global variable used in the function body without further initialization. Uninitialized globals are nil, so nil is passed to InputConsole() and the error message is telling you the truth.
Old answer that didn't solve it
Lua 5.1 deprecated that usage, and Lua 5.2 removed it entirely.
I'm not sure from the code fragments provided which version of Lua is actually used in this game, but the symptom is consistent with missing the automatically generated arg table.
I would write the function like this:
function InputConsole(...)
Console_Input(string.format(...))
end
But you could also add local arg = {...} as the first line of the function and get much the same effect as provided by Lua 5.0 at the expense of creating (and discarding) the temporary table. The differences are subtle, and mostly have to do with the treatment of nil in tables.
For clarity, I would prefer name the first argument, as it is not really optional.
function InputConsole(fmt, ...)
Console_Input(string.format(fmt, ...))
end
And if you can count on that argument being a string, that could be simplified further to
function InputConsole(fmt,...)
Console_Input(fmt:format(...))
end
If its stringiness is of concern, just say fmt = tostring(fmt) or possibly assert(type(fmt)=="string") before the call to Console_Input().