Q:

attempt to perform arithmetic on a table value: Lua error message

stage:addEventListener(Event.ENTER_FRAME, 
function()
Graphic:setRotation(Graphic:getRotation()+ (Timer.delayedCall(math.random(4, 8) , 
function () speed = math.random(1, 30) 
return speed
end)
))
end)

Basicallu, what I am trying to do is, change the speed of rotation randomly, but since I do not want it to change at every second, I tried using Timer.delayedCall in Gideros, but it gives an error that says attempt to perform arithmetic on a table value: Lua error message. How can I fix this?

A:

According to Gideros documentation, Timer.delayedCall returns a 'Timer' object, which should be the table the error message is referring to. 
http://docs.giderosmobile.com/reference/gideros/Timer/delayedCall
I'm not intimately familiar with Gideros but I believe you would want something closer to this:
stage:addEventListener(Event.ENTER_FRAME, 
    function()
        Timer.delayedCall(math.random(4,8), 
            function()
                Graphic:setRotation( Graphic:getRotation() + math.random(1,30) )
            end)
    end)

However, this will presumably still fire with every ENTER_FRAME event, just that each change will be delayed randomly. You may want to use a control variable so that only one Timer can be pending:
local timerPending=false
stage:addEventListener(Event.ENTER_FRAME, 
    function()
        if timerPending then return end
        timerPending=true
        Timer.delayedCall(math.random(4,8), 
            function()
                Graphic:setRotation( Graphic:getRotation() + math.random(1,30) )
                timerPending=false
            end)
    end)

