LUA error: attempt to call global 'function_name' (a nil value)

[rustam]

Hi there,

I'm trying to call the function 'Armrest_Toggle' with a button assigned through FSUIPC as follows:

if ipcPARAM == 0 then

	Armrest_Toggle()

end

local function Armrest_Toggle()
    ipc.writeLvar(nToggleVal(ipc.readLvar("L:Twot_Armrest"), 0, 1))
end

local function nToggleVal(nCurrVal, nVal1, nVal2)
	if nCurrVal == nVal1 then
		return nVal2
	else
		return nVal1
	end
end

I'm tracing the changes in LVars and when I press the assigned button, I get this error:

273111 *** LUA Error: ...Games\Microsoft Flight Simulator X\Modules\dhc-6.lua:26: attempt to call global 'Armrest_Toggle' (a nil value)

And here is the content of FSUIPC.ini, as relates to the particular aircraft I've loaded into the sim:

[JoyNames]
AutoAssignLetters=No
0=X52 Pro Flight Controller
0.GUID={A1946F60-C51A-11E6-8005-444553540000}

[Profile.DHC-6]
1=Aerosoft DHC-6

[Buttons.DHC-6]
0=P0,1,CL1:R,0 ; armrest toggle 	-{Lua dhc-6}-

[General]
ShortAircraftNameOk=Substring

[LuaFiles]
1=dhc-6
2=ipcReady
3=linda

 

I wonder what can cause this error? Thanks in advance!!!

FSUIPC4.log

[Thomas Richter]

Hi,

in C/C++ you need a forward declaration to have the definition below the actual call. So you write bottom up if you don't do this, means you might need to have the local function Armrest_Toggle()... above the calling part.

The error says you are looking for a global function, that means your actual function is not visible when you call it.

Thomas

[rustam]

Thank you, Thomas!!! Strange, I thought calling functions was just a matter of proper environment definition (local or global), but direction of declaration is smth new for me...

I'll try your suggestion and return to this thread.

And Happy New Year!!!

[rustam]

I tried this to no avail yet...

function nToggleVal(nCurrVal, nVal1, nVal2)
	if nCurrVal == nVal1 then
		return nVal2
	else
		return nVal1
	end
end

function Armrest_Toggle()
    ipc.writeLvar(nToggleVal(ipc.readLvar("L:Twot_Armrest"), 0, 1))
end

if ipcPARAM == 0 then

	Armrest_Toggle()
	
end

FSUIPC.ini is unchanged - FSUIPC recognizes the button OK. The problem is associated with function call I think. But I don't know why the above syntax doesn't work... :(

[Thomas Richter]

Hi,

looking at

function Armrest_Toggle()
    ipc.writeLvar(nToggleVal(ipc.readLvar("L:Twot_Armrest"), 0, 1))
end

the write should of course have the L:"LVariablename" you want to write to but you don't supply any, just the returned nVal1 !?

ipc.writeLvar(“name”, n)

Thomas

[rustam]

OMG, it was so obvious... This one works finally:

function Armrest_Toggle()
    ipc.writeLvar("L:Twot_Armrest", nToggleVal(ipc.readLvar("L:Twot_Armrest"), 0, 1))
end

Thank you VERY much for the hint, Thomas!!!