why does the Director class make my global variables not visible to external modules in corona? - global-variables

Question

I'm doing basic stuff to understand using external classes/modules with global variables, and now I'm trying to add director. But when I added the director class, my global variables such as applyThrust then became not visible in the external class.
It worked fine before refactoring for Director. Before using director, I only had 2 files, rocket.lua and the mainScreen.lua file below was simply main.lua. I used the same globals, applyThrust and thrustForceY, and it worked.
By the way, the director functionality of switching screens appears to work fine, other than this odd side effect of making the global variables not visible.
I asked this on the corona director forums and got no response so I thought I'd try reliable STO.
Here's the files I'm using with the director stuff :
main.lua
display.setStatusBar (display.HiddenStatusBar)
local director = require ("director")
local mainGroup = display.newGroup()
local function main()
mainGroup:insert(director.directorView)
director:changeScene("menu")
return true
end
main()
menu.lua
module(..., package.seeall)
function new()
local localGroup = display.newGroup()
------------------------------------------------------------------------------
local playText = display.newText("Play",160, 100, "Arial", 32)
playText:setTextColor(0, 0, 255)
localGroup:insert(playText)
local function pressPlay (event)
if event.phase == "ended" then
director:changeScene ("mainScreen")
end
end
playText:addEventListener ("touch", pressPlay)
------------------------------------------------------------------------------
return localGroup
end
mainScreen.lua
local Rocket = require( "rocket" )
local physics = require( "physics" )
module(..., package.seeall)
function new()
local localGroup = display.newGroup()
------------------------------------------------------------------
score = 100
physics.start()
local ground = display.newRect( 60, 170, 60, 60 )
physics.addBody( ground, "static", { density=3.0, friction=0.5, bounce=0.2 } )
rocket = Rocket.new(80, 110)
local upText = display.newText("Up",160, 300, "Arial", 32)
upText:setTextColor(0, 0, 255)
------------- my global variables -----------
thrustForceY = -100
applyThrust = false
local function pressUp (event)
local t = event.target
local phase = event.phase
if( "began" == phase ) then
display.getCurrentStage():setFocus( t )
t.isFocus = true
if( not applyThrust ) then
rocket:addThrust()
end
rocket:applyForce(0, thrustForceY, rocket.x, rocket.y)
applyThrust = true
elseif "ended" == phase or "cancelled" == phase then
rocket:removeThrust()
display.getCurrentStage():setFocus( nil )
t.isFocus = false
applyThrust = false
end
return true
end
upText:addEventListener ("touch", pressUp)
----------------------------------------------
return localGroup
end
rocket.lua
module(..., package.seeall)
local physics = require( "physics" )
--constructor--------------------
function new(x, y)
rocket = display.newGroup()
local body = display.newRect( x, y, 25, 60 )
physics.addBody( body, { density=1.5, friction=0.5, bounce=0.2 } )
body.isFixedRotation = true
rocket:insert(body)
local thrust = {}
function rocket:addThrust()
thrust = display.newRect( body.x, body.y + (body.height / 2) , 10, 10 )
thrust.y = body.y + (body.height / 2) + (thrust.height / 2)
physics.addBody( thrust, { density=1.5, friction=0.5, bounce=0.2 } )
rocket:insert(thrust)
end
function rocket:removeThrust()
rocket:remove(thrust)
end
function rocket:applyForce( xForce, yForce, atPointX, atPointY )
body:applyForce( xForce, yForce, atPointX, atPointY )
end
----------------------------------------------------------------------
-- enterFrame listener for rocket
----------------------------------------------------------------------
function rocket:enterFrame (event)
if( applyThrust ) then
body:applyForce(0, thrustForceY, body.x, body.y)
thrust.y = body.y + (body.height / 2) + (thrust.height / 2)
thrust.x = body.x
else
print("applyThrust is nil")
end
end
Runtime:addEventListener("enterFrame", rocket)
return rocket
end

Answer 1

A global variable in Corona is as simple as using "_G." before your variable.
For example:
lives = 3
Would become:
_G.lives = 3
But Director already has functionality to pass parameters to another scene.... there is no need to use globals.
scene1.lua
local params = {
param1= "http://github.com/",
param2 = "bla-bla"
}
director:changeScene( params, "screen2", "moveFromRight" )
screen2.lua
new = function ( params )
local url = params.param1
local bla = params.param2
...
end

Answer 2

Good point.
Also, you can put all your variables in a file you created and access it from any module.