is this valid code?

Getting Started Newbie Questions
#1

Hi

I want to cycle through an array table and display some of the contents (it’s actually a page of scores).

This is the gist of what I have:

for i = 1, #myTable do         local myText = display.newText(myGroup, myTable[i].myField, 100, 100 \* i, FONT\_NAME, 30 )  ... end

and then later in another function:

myGroup:removeSelf() 

The question I have around this is that I wind up with 8 text objects on the screen, but there has only ever been one variable name. It works just fine on my test devices (iOS 7 iPads and Asus tablet) and the simulator but I’m wondering whether it’s sloppy code. Should I be dynamically generating a new variable name each time through the loop, based on the value of “i” ?

          

thanks,

David

#2

This is one of those areas that creates some memory management confusion.  If you were not inserting them into the group, then you would certainly be creating a memory leak since you’re overwriting the pointer to the previous display object.

But since you’re inserting it into a group, the group is holding a reference to each display.newText object and when the you do the removeSelf() on the group, it cleans up it’s children for you, so you’re not leaking memory. 

Personally I would put them in an array, though in this case, you would actually end up using a little more Lua memory than the way you’re doing it.

Rob

#3

Nothing sloppy about using a temp variable to load an array of objects in a loop - it’s actually very efficient / clean. But, if you’re looking for some criticism on sloppiness / neatness, I’d change basically all of your variable names.

The variable “i” might be renamed numRadarBlips… The var myText might be renamed blipLabel, myGroup --> radarGroup, FONT_NAME --> radarFont, etc etc

Of course the naming depends on how the vars are actually used. But naming then closer to what the objects are / do will greatly help other coders pick up your code (or you, a year or two later).

#4

Hi

Thanks for the tips. I actually just used those variable names for simplicity’s sake in this example. In my code I use very descriptive (and consequently sometimes very long) names for my functions and variables.

cheers,

david

#5

This is one of those areas that creates some memory management confusion.  If you were not inserting them into the group, then you would certainly be creating a memory leak since you’re overwriting the pointer to the previous display object.

But since you’re inserting it into a group, the group is holding a reference to each display.newText object and when the you do the removeSelf() on the group, it cleans up it’s children for you, so you’re not leaking memory. 

Personally I would put them in an array, though in this case, you would actually end up using a little more Lua memory than the way you’re doing it.

Rob

#6

Nothing sloppy about using a temp variable to load an array of objects in a loop - it’s actually very efficient / clean. But, if you’re looking for some criticism on sloppiness / neatness, I’d change basically all of your variable names.

The variable “i” might be renamed numRadarBlips… The var myText might be renamed blipLabel, myGroup --> radarGroup, FONT_NAME --> radarFont, etc etc

Of course the naming depends on how the vars are actually used. But naming then closer to what the objects are / do will greatly help other coders pick up your code (or you, a year or two later).

#7

Hi

Thanks for the tips. I actually just used those variable names for simplicity’s sake in this example. In my code I use very descriptive (and consequently sometimes very long) names for my functions and variables.

cheers,

david