Scope problem?

Dafb

I am rewriting my code to implement scenemanager. Being just a hobby programmer, I ran in various expected scope problems. But this one really surprised me.

So my main.lua for now is

application:setBackgroundColor(0x000000)   print("Starting...")   --define scenes sceneManager = SceneManager.new({ --start scene ["start"] = start, ["level1"] = level1, ["gameover"] = GameOver })     --add manager to stage stage:addChild(sceneManager)   sceneManager:changeScene("level1")

My level1.lua starts with this line:

level1 = gideros.class(Sprite)

Somewhere, I have a

function level1:moveRedMotherShip(dt)

And its moveBlueMotherShip(dt) equivalent.
Finally, here is my onEnterFrame function:

function level1:onEnterFrame(e)   local dt = e.deltaTime   local numSprite = stage:getNumChildren()   level1:moveRedMotherShip(dt) -- move red ship level1:moveBlueMotherShip(dt) end

Everything works here. What does not work is when I change

local numSprite = stage:getNumChildren()

into

local numSprite = level1:getNumChildren()

It spits "index '__userdata' cannot be found"

Yet,

level1:moveBlueMotherShip(dt)

works.
Why the latter works and not level1:getNumSprite() ? I thought that "level1" being a sprite could call any sprite method. Please enlight me. There is something here I need to understand.

MoKaLux

Dafb said:

level1 = gideros.class(Sprite)

change it to Core.class(Sprite), it's better.

Dafb said:

local numSprite = stage:getNumChildren()

into

You need to call:

local numSprite = self:getNumChildren()

Dafb said:

Why the latter works and not level1:getNumSprite() ? I thought that "level1" being a sprite could call any sprite method. Please enlight me. There is something here I need to understand.

I can't really explain why but I think level1 is a class and self is a sprite.

rrraptor

Dafb said:

Why the latter works and not level1:getNumSprite() ? I thought that "level1" being a sprite could call any sprite method. Please enlight me. There is something here I need to understand.

MoKaLux said:

I can't really explain why but I think level1 is a class and self is a sprite.

"level1" is a class. And "self" refers to object instance. In your case instance is created by sceneManger.

@Dafb
You can read about "self" here: http://www.lua.org/pil/16.html

Also "level1:getNumSprite()" can be used as "level1.getNumSprite(self)"

Dafb

Thanks to you guys, I fixed the problem.

I believe the main issue was I forgot to add

require ("scenemanager")

in main.lua.

Silly stuff! I also use now as advised

Core.class instead of gideros.class

Everything works now and I will read the provided link.

Thank you again.