Lua Callback Example

class 'B'

function B:InitCount()

    self.count = 1000

end

//this - optional paremeter (can be nil) which is a copy (i think reference) of the "self" of the class that set the callback.
function B:SetCallback(func, this)

    self.callBackFunction = func
    self.callBackSelf = this

end

function B:RunCallback()

    if self.callBackFunction then
        self.callBackFunction(self.callBackSelf)
    end

end

class 'A'

local bInstance = B()

function A:InitCount()

    self.count = 7

end

function A:Work()

    if not self.count then
        self.count = 1
    else
        self.count = self.count + 1
    end

    Print(self.count)

end

function A:SetCallback()

    bInstance:SetCallback(A.Work, self) //if A:Work() didn't rely on self then it could of been done like this: bInstance:SetCallback(A.Work)

end

local aInstance = A()
A:InitCount() // sets A's self.count to 7
B:InitCount() // sets B's self.count to 1000
aInstance:SetCallback() //tells the bInstance how to call the A:Work() function

bInstance:RunCallback() //runs A:Work() function, prints 8 to console
bInstance:RunCallback() //runs A:Work() function, prints 9 to console
bInstance:RunCallback() //runs A:Work() function, prints 10 to console