Accessing parent class

aukStudios · August 27, 2013, 6:13pm

Well, the following works fine for me:

[lua]

local char = {}

char.who = “hero”

char.displayHero = {}

char.displayHero.parent = char

print (char.displayHero.parent) – table : 00ED7A70

local test = char.displayHero.parent

print (test.who) – hero

print (char.who) – hero

[/lua]

The last five lines are your lines exactly, except that all three prints work. The first three lines are just me constructing a simple object.

So, it seems like it must have to do with your constructor. Can you post your full constructor code?

Andrew

travaildereligion · August 27, 2013, 6:44pm

This is the constructor from my hero.lua file

function hero.new(startingTile)&nbsp;&nbsp; &nbsp;-- constructor local newhero = { &nbsp;&nbsp; &nbsp;who = "hero", &nbsp;&nbsp; &nbsp;frameNumber = 1, &nbsp;&nbsp; &nbsp;displayHero = nil, &nbsp;&nbsp; &nbsp;lastIdlePos = "idleUp", &nbsp;&nbsp; &nbsp;pos = startingTile, &nbsp;&nbsp; &nbsp;heroSequenceData = &nbsp;&nbsp; &nbsp;{ &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;{ name="idleUp", start=3, count=1, time=3000 } , &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;{ name="idleDown", start=6, count=1, time=3000 } , &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;{ name="idleRight", start=9, count=1, time=3000 } , &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;{ name="idleLeft", start=12, count=1, time=3000 } , &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;{ name="runUp", start=3, count=3, time=400 } , &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;{ name="runDown", start=6, count=3, time=400 } , &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;{ name="runRight", start=9, count=3, time=400 } , &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;{ name="runLeft", start=12, count=3, time=400 } , &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;{ name="random", frames={ 3, 9, 6, 12 }, time=300 } &nbsp;&nbsp; &nbsp;} } return setmetatable( newhero, hero\_mt ) end &nbsp;

Here’s the code from my other lua file :

&nbsp;&nbsp;&nbsp; char = hero.new(1) &nbsp;&nbsp; &nbsp;char.displayHero =&nbsp; display.newSprite( heroSheet, char.heroSequenceData ) &nbsp;&nbsp; &nbsp;char.displayHero.xScale = tileDimension / tileDefaultSize &nbsp;&nbsp; &nbsp;char.displayHero.yScale = tileDimension / tileDefaultSize &nbsp;&nbsp; &nbsp;char.displayHero.x = tileArray[1].displayTile.x &nbsp;&nbsp; &nbsp;char.displayHero.y = tileArray[1].displayTile.y &nbsp;&nbsp; &nbsp;char.displayHero:setSequence(char.lastIdlePos) &nbsp;&nbsp; &nbsp;char.displayHero:play() &nbsp;&nbsp; &nbsp; &nbsp;&nbsp; &nbsp;char.displayHero.parent = char &nbsp;&nbsp; &nbsp;print (char.displayHero.parent)&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;--&nbsp; table : 00ED7A70 &nbsp;&nbsp; &nbsp;local test = char.displayHero.parent &nbsp;&nbsp; &nbsp;print (test.who)&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;nil &nbsp;&nbsp; &nbsp;print (char.who)&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; hero &nbsp;

aukStudios · August 27, 2013, 7:11pm

Nothing is jumping out at me that looks wrong. It might have something to do with your metatable.

What happens if you just print(test), print(char), and print(char.displayHero.parent). Do they all print out the same table reference?

Andrew

travaildereligion · August 27, 2013, 7:37pm

&nbsp;&nbsp;&nbsp; print (test)&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;-- table : 00E4E180 &nbsp;&nbsp; &nbsp;print (char)&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;-- table : 0A1646B8 &nbsp;&nbsp; &nbsp;print (char.displayHero.parent)&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;-- table : 00E4E180 &nbsp;

hmm… char is supposed to be different I think, the other two are the same table

aukStudios · August 27, 2013, 7:44pm

I now more strongly suspect that it’s something funky going on with your metatable. Can you post the metatable code?

If I run the following code, all three prints print the same table reference, as expected:

[lua]

local char = {}

char.who = “hero”

char.displayHero = {}

char.displayHero.parent = char

local test = char.displayHero.parent

print(char)

print(test)

print(char.displayHero.parent)

[/lua]

Andrew

travaildereligion · August 27, 2013, 8:17pm

I’ll be honest… I don’t think I know what the metatable code is and I probably don’t have any… :ph34r:

Here’s my whole file :

------------------------------------------------- -- -- hero.lua -- ------------------------------------------------- local hero = {} local hero\_mt = { \_\_index = hero }&nbsp;&nbsp; &nbsp;-- metatable &nbsp; ------------------------------------------------- -- PRIVATE FUNCTIONS ------------------------------------------------- &nbsp; &nbsp; local function Set (list) &nbsp; local set = {} &nbsp; for \_, l in ipairs(list) do set[l] = true end &nbsp; return set end ------------------------------------------------- -- PUBLIC FUNCTIONS ------------------------------------------------- &nbsp; &nbsp; &nbsp; &nbsp; --------------------------------- -- -- who&nbsp;&nbsp; &nbsp;&nbsp; : string --&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;type of character -- --------------------------------- &nbsp; function hero.new(startingTile)&nbsp;&nbsp; &nbsp;-- constructor local newhero = { &nbsp;&nbsp; &nbsp;who = "hero", &nbsp;&nbsp; &nbsp;frameNumber = 1, &nbsp;&nbsp; &nbsp;displayHero = nil, &nbsp;&nbsp; &nbsp;lastIdlePos = "idleUp", &nbsp;&nbsp; &nbsp;pos = startingTile, &nbsp;&nbsp; &nbsp;heroSequenceData = &nbsp;&nbsp; &nbsp;{ &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;{ name="idleUp", start=3, count=1, time=3000 } , &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;{ name="idleDown", start=6, count=1, time=3000 } , &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;{ name="idleRight", start=9, count=1, time=3000 } , &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;{ name="idleLeft", start=12, count=1, time=3000 } , &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;{ name="runUp", start=3, count=3, time=400 } , &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;{ name="runDown", start=6, count=3, time=400 } , &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;{ name="runRight", start=9, count=3, time=400 } , &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;{ name="runLeft", start=12, count=3, time=400 } , &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;{ name="random", frames={ 3, 9, 6, 12 }, time=300 } &nbsp;&nbsp; &nbsp;} } return setmetatable( newhero, hero\_mt ) end &nbsp; ------------------------------------------------- &nbsp; ------------------------------------------------- &nbsp; &nbsp; ------------------------------------------------- &nbsp; ------------------------------------------------- &nbsp; &nbsp; ------------------------------------------------- &nbsp; return hero &nbsp;

aukStudios · August 27, 2013, 8:33pm

Hmm. You’re metatable doesn’t seem to be doing anything significant here. But just in case, try replacing the line “return setmetatable( newhero, hero_mt )” with simply “return newhero” and see if that makes a difference.

Andrew

travaildereligion · August 27, 2013, 8:38pm

hmm, I still have the same problem despite the change.

aukStudios · August 27, 2013, 8:47pm

OK, then you can put that line back to the way it was.

It’s possible that ‘parent’ is a field that’s already used by the sprite object. Try changing ‘parent’ to ‘myParent’ and see if that makes a difference.

Andrew

travaildereligion · August 27, 2013, 10:00pm

Ah yes that was it, I thought I already tested that though … must have made a mistake.

Thanks for putting up with my problem Andrew!

aukStudios · August 28, 2013, 3:43am

Cool, glad you got it working! - Andrew