chatsetattr no lower than 0

Is there a way to have chatsetattr stop reducing values below 0?

Does your macro rely in decrementing? Or calculations that result in a number that then gets applied/used in the ChatSetAttr call?

Here's an inline solution using MathOps, demonstrating decrementing an arrows value and stopping at 0:

{& math max(0, @{Archelena|arrows} - 1) }

Or, using Fetch, too, you can supply a default value for the attribute if it doesn't exist:

{& math max(0, @(Archelena.arrows[0]) - 1) }

What does a typical macro look like where ChatSetAttr tries to reduce a value below 0?

!serattr --sel --arrows|-1

Yep, so someone may be able to come along and tell you more about a built-in limiter for ChatSetAttr, but until then I think you can do basically what I mentioned, above, provided the -1 is a trigger to CSA to decrement, and we can skip that by just supplying a value.

Grab MathOps, SelectManager, and ZeroFrame and get them installed. If you want to default a value in as a starting point if the attribute isn't found, grab Fetch, too. (I know ChatSetAttr creates and sets the attribute if it doesn't exist; but we need it sooner than that. Using an @{selected} call will stop your macro before it even gets there... but Fetch with a default value will let you proceed.)

!setattr --sel --arrows|{&math max(0,@{selected|arrows}-1)}

Here's the alternate version using the Fetch construction instead of the Roll20 @{selected...}...

!setattr --sel --arrows|{&math max(0,@(selected.arrows[0])-1)}

{&0 fetch math}

ChatSetAttr has a built in way to do it, just use

!modbattr --sel --arrows|-1

Chatsetattr not going below 0 would be "Battr" for each command.  modbattr, setbattr.  Fair warning, it will NOT warn you that its falsely succeeding when it reduces 0 to 0.  I believe it will also not go over the maximum either.  

Thanks Persephone and DM Eddie. Those worked perfectly.