button reference

rgame · June 24, 2013, 3:43pm

Good Morning (to those in an appropriate time zone),

I am creating a simple multi button scrolling menu (using widgets scrollView and button), however i’ve run into a snag involving references to my object

I am trying to create my scrollView and my buttons in a seperate file, while keeping the references for those widgets in another file so that i can destroy them at the end of a certain view.

I think the root of my problem is that my values are pass by value when i want them to be pass by reference.

Here is an example, lets make it a car one for fun, of whats causing the problem:

In one file

--main.lua &nbsp; require("displayManager.lua") require("listeners.lua") &nbsp; local displayObject = { &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ferrariManufacturerButton, &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;maseratiManufacturerButton, } &nbsp; function displayMenu() &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;local buttonFerrari = "Ferrari" &nbsp;&nbsp;&nbsp;&nbsp;local buttonFerrariLeft = display.viewableContentWidth/4 &nbsp;&nbsp;&nbsp;&nbsp;local buttonFerrariTop = display.viewableContentHeight/3 &nbsp;&nbsp;&nbsp;&nbsp;local buttonFerrariImage = "images/ManufacturerMenu/blueButton.jpg" &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;local buttonWidth = 8\*30 &nbsp;&nbsp;&nbsp;&nbsp;local buttonHeight = &nbsp;1 \* 30 &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;createButton(displayObject.ferrariManufacturerButton, buttonFerrari, buttonFerrariLeft,buttonFerrariTop,buttonWidth, &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;buttonHeight,buttonFerrariImage,manufacturerFerrariMenuListener) &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;print(displayObject.ferrariManufacturerButton) -- returns nil :( &nbsp;&nbsp;&nbsp;&nbsp; end &nbsp;

while in my other file :

&nbsp; --displayManager.lua &nbsp; function createButton(buttonObject,buttonName, topLeft, topRight, bWidth,bHeight, buttonImage, listenerThing) &nbsp;&nbsp;&nbsp;&nbsp;local widget = require "widget" &nbsp;&nbsp;&nbsp;&nbsp;buttonObject = widget.newButton &nbsp;&nbsp;&nbsp;&nbsp;{ &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;&nbsp;left = topLeft, &nbsp;&nbsp;&nbsp;&nbsp; &nbsp; &nbsp;top = &nbsp;topRight, &nbsp;&nbsp;&nbsp;&nbsp; &nbsp; &nbsp;width = bWidth, &nbsp;&nbsp;&nbsp;&nbsp; &nbsp; &nbsp;height = bHeight, &nbsp;&nbsp;&nbsp;&nbsp; &nbsp; &nbsp;defaultFile = buttonImage, -- both textures for how to button looks pressed and released&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; &nbsp; &nbsp;id = buttonName, &nbsp;&nbsp;&nbsp;&nbsp; &nbsp; &nbsp;onRelease = listenerThing &nbsp;&nbsp;&nbsp;&nbsp;} &nbsp; end

So unfortunately, my print statement in my main returns a value of nil. I dont like it to return a value of nil, because at some point when i call a new function to change the menu, i’d like to remove that object completely.

Though this example doesn’t show me creating a scrollView or placing the button in scrollView, the reason why i didn’t include it was because of a nil reference error i get to both my scrollView variable and my button variables because (of what I assume) is how i have my system currently set up

How should I proceed?

roaminggamer · June 24, 2013, 4:00pm

rgame,

Pass your displayObject table an and index instead, like this (code trimmed to important bits):

local displayObject = { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;ferrariManufacturerButton, &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;maseratiManufacturerButton, } ... &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; createButton(displayObject, 'ferrariManufacturerButton', ... &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; ... function createButton(buttonContainer, containerIndex, ... &nbsp; &nbsp;local widget = require "widget" &nbsp; &nbsp;local tmpButton = widget.newButton ... &nbsp; &nbsp; buttonContainer[containerIndex] = tmpButton ... end &nbsp;

Alternately, you could return the button reference and assign it after the call to createButton()

roaminggamer · June 24, 2013, 4:00pm

rgame,

Pass your displayObject table an and index instead, like this (code trimmed to important bits):

local displayObject = { &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;ferrariManufacturerButton, &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;maseratiManufacturerButton, } ... &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; createButton(displayObject, 'ferrariManufacturerButton', ... &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; ... function createButton(buttonContainer, containerIndex, ... &nbsp; &nbsp;local widget = require "widget" &nbsp; &nbsp;local tmpButton = widget.newButton ... &nbsp; &nbsp; buttonContainer[containerIndex] = tmpButton ... end &nbsp;

Alternately, you could return the button reference and assign it after the call to createButton()