Roku Developer Program

[squirreltown]

Just bumped into the variable limit. Manged to do what i needed but I'm within 3-4 of it.
What is the limit, and is it global per channel or per .brs file or per function?
Thanks.

[TheEndless]

In the debugger, you can type "stats" to get a list of all of the limits. Variables is 255, which I believe is per function, but I'm not positive.

[squirreltown]

Thank you Endless.

[Komag]

Is this confirmed in anyone's experience, that it's per function, and that it's 255?

So if I want to set a bunch of sound variables, I can just do something like this:

' within Main()
sounds = getSounds()

FUNCTION getSounds() ' trig by Main(1) near top
	hitMon = CreateObject("roAudioResource", "pkg:/sounds/hitMon.wav")
	missMon = CreateObject("roAudioResource", "pkg:/sounds/missMon.wav")
	hitPlayer = CreateObject("roAudioResource", "pkg:/sounds/hitPlayer.wav")
	missPlayer = CreateObject("roAudioResource", "pkg:/sounds/missPlayer.wav")
	deathMon = CreateObject("roAudioResource", "pkg:/sounds/deathMon.wav")
	sounds = {hitMon: hitMon, missMon: missMon, hitPlayer: hitPlayer, missPlayer: missPlayer, deathMon: deathMon} ' I don't think this is best way to do it
	RETURN sounds
END FUNCTION

That way Main() is only adding one more variable, an AA with all the sounds.
(Would this be the right approach?)

[Rek]

"Komag" wrote:
Is this confirmed in anyone's experience, that it's per function, and that it's 255?

So if I want to set a bunch of sound variables, I can just do something like this:

' within Main()
sounds = getSounds()

FUNCTION getSounds() ' trig by Main(1) near top
	hitMon = CreateObject("roAudioResource", "pkg:/sounds/hitMon.wav")
	missMon = CreateObject("roAudioResource", "pkg:/sounds/missMon.wav")
	hitPlayer = CreateObject("roAudioResource", "pkg:/sounds/hitPlayer.wav")
	missPlayer = CreateObject("roAudioResource", "pkg:/sounds/missPlayer.wav")
	deathMon = CreateObject("roAudioResource", "pkg:/sounds/deathMon.wav")
	sounds = {hitMon: hitMon, missMon: missMon, hitPlayer: hitPlayer, missPlayer: missPlayer, deathMon: deathMon} ' I don't think this is best way to do it
	RETURN sounds
END FUNCTION

That way Main() is only adding one more variable, an AA with all the sounds.
(Would this be the right approach?)

The limit appears to be 253 on my Roku 2. The following snippet works fine, until adding one more variable ("x253 = 253"):

function main() as Void
	x0 = 0
	x1 = 1
	x2 = 2
	x3 = 3
	x4 = 4
	x5 = 5
	x6 = 6
	x7 = 7
	x8 = 8

	' ... snip a couple hundred lines ...
	
	x247 = 247
	x248 = 248
	x249 = 249
	x250 = 250
	x251 = 251
	x252 = 252

	?"Done"
end function

The limit also appears to be imposed on individual functions, not the .brs file or channel as a whole. I verified this by creating two functions: `a`, and `b` which also have 253 variables. This gives a total of 759 variables across 3 functions in 1 file.

The following code uses all 3 functions: `main` calls `a`, then `a` calls `b`. While `b` is executing, all 759 variables are in-memory, and it works fine.

function main() as Void
	?"enter Main"
	x0 = 0
	x1 = 1
	x2 = 2
	x3 = 3
	x4 = 4
	x5 = 5
	x6 = 6
	x7 = 7
	x8 = 8
	x9 = 9

	' ... snip a couple hundred lines ...

	x247 = 247
	x248 = 248
	x249 = 249
	x250 = 250
	x251 = 251
	x252 = 252

	a()
	?"exit Main (done)"
end function

function a() as Void
	?"enter A"
	x0 = 0
	x1 = 1
	x2 = 2
	x3 = 3
	x4 = 4
	x5 = 5
	x6 = 6
	x7 = 7
	x8 = 8
	x9 = 9

	' ... snip a couple hundred lines ...

	x247 = 247
	x248 = 248
	x249 = 249
	x250 = 250
	x251 = 251
	x252 = 252

	b()
	?"exit A"
end function

function b() as Void
	?"enter B"
	x0 = 0
	x1 = 1
	x2 = 2
	x3 = 3
	x4 = 4
	x5 = 5
	x6 = 6
	x7 = 7
	x8 = 8
	x9 = 9

	' ... snip a couple hundred lines ...

	x247 = 247
	x248 = 248
	x249 = 249
	x250 = 250
	x251 = 251
	x252 = 252

	?"exit B"
end function

As an aside: I think its safe to say that if you are actually hitting this limit, its probably time to start breaking the function up into smaller ones... In general having monolithic functions makes your code harder to maintain and understand.

My general rule is that if a function is more than a handful of lines (~ 10) it's too long and should be broken up if possible. Additionally, if the exact same lines of code appear in more than 3 places, its time to make a function that does the job. There are sometimes performance, or architectural reasons not to do so, but in general I find it to be a good way to operate.

[TheEndless]

If you issue the stats command in the debugger, it'll give you the current counts and the limits.

[squirreltown]

"Rek" wrote:

My general rule is that if a function is more than a handful of lines (~ 10) it's too long and should be broken up if possible.

10 ? thats a typo right?
You can't even do this in 10 lines.

				while true		
		   		draw something
				swapbuffers()
				msg = port.getmessage()
					if type(msg) = "roUniversalControlEvent"
						button = msg.getint()
						if button=0
							return
						end if
					end if
				end while	

You must have a bizzilion functions. :shock:

[Rek]

"squirreltown" wrote:

"Rek" wrote:

My general rule is that if a function is more than a handful of lines (~ 10) it's too long and should be broken up if possible.

10 ? thats a typo right?
You can't even do this in 10 lines.

				while true		
		   		draw something
				swapbuffers()
				msg = port.getmessage()
					if type(msg) = "roUniversalControlEvent"
						button = msg.getint()
						if button=0
							return
						end if
					end if
				end while	

You must have a bizzilion functions. :shock:

As I say, there are architectural reasons to have longer functions. I only have 1 run-loop in my application, so the logic is not duplicated anywhere; the function it lives in is around 120 lines 😞 The key here is that it performs a specific task, and is implemented as a bunch of calls to other functions (with comments!). So, even though its long, its still readable and maintainable.

But I do have quite a few...

$ grep -inR "^function" . | wc -l
2831

[squirreltown]

Well I cant write a function that small but here is a whole channel in 5 lines:

   screen = CreateObject("roScreen", true,1280, 720)
	while true
	screen.clear(&hFF0000FF)
	screen.swapbuffers()
	end while

you don't even have to wrap it in Sub Main()/End sub
the mainfest file only needs a single space in it to be legal. So we'll call it six lines. How's that for efficient?

[Rek]

"squirreltown" wrote:
Well I cant write a function that small but here is a whole channel in 5 lines:

   screen = CreateObject("roScreen", true,1280, 720)
	while true
	screen.clear(&hFF0000FF)
	screen.swapbuffers()
	end while

you don't even have to wrap it in Sub Main()/End sub
the mainfest file only needs a single space in it to be legal. So we'll call it six lines. How's that for efficient?

Wow, I didn't realise a manifest with only whitespace is legal