Sort bug

[Geoff Canyon]

With 9.6.9 on a mac and a field where the second and third items of each
line are numbers:

   sort lines of fld 1 numeric by item 2 of each + item 3 of each -- works
   sort lines of fld 1 numeric by value(item 2 of each + item 3 of each) --
works
   sort lines of fld 1 numeric by merge("[[item 2 of each + item 3 of
each]]") -- works

and

on mouseUp
   sort lines of fld 1 numeric by sortVal(each)
end mouseUp

function sortVal S
   return item 2 of S + item 3 of S
end sortVal

works.

I haven't checked, but I'd guess that performance degrades with each
further method.

They all work if one or both of the items are empty.

If there is an entry that has a non-numeric value in item 2 or 3:

   sort lines of fld 1 numeric by item 2 of each + item 3 of each --
partially sorts and throws an error
   sort lines of fld 1 numeric by value(item 2 of each + item 3 of each) --
partially sorts and throws an error
   sort lines of fld 1 numeric by merge("[[item 2 of each + item 3 of
each]]") -- surprisingly, works -- error lines are seemingly sorted with a
value of negative infinity?

And the function sort also sorts based on a negative infinity value for
errors. I'm not sure I'd consider that a bug.

And this works:

   sort lines of fld 1 numeric by merge("<?if item 2 of each is not a
number or item 3 of each is not a number then return 0 else return item 2
of each + item 3 of each?>")

And of course sorting by this function does the same thing:

function sortVal S
   if item 2 of S is not a number or item 3 of S is not a number then
return 0
   return item 2 of S + item 3 of S
end sortVal



On Thu, Aug 31, 2023 at 9:30 PM Brian Milby via use-livecode <
use-livecode at lists.runrev.com> wrote:

> I just tried this in 10dp5 and the sort didn’t completely bail (it put the
> error value first) but it did error when including inline (as in the bug
> report).  If I add a try, then it will stop on the throw.  Not sure how
> much this would slow down execution though.
>
> function myVal pStr
>    local tResult
>    try
>       put item 1 of pStr + item 2 of pStr into tResult
>    catch errorVariable
>       throw "Bad data"
>    end try
>    return tResult
> end myVal
>
> Brian Milby
> brian at milby7.com
>
> > On Aug 31, 2023, at 7:53 PM, Alex Tweedly via use-livecode <
> use-livecode at lists.runrev.com> wrote:
> >
> > 
> >> On 01/09/2023 00:37, Bob Sneidar via use-livecode wrote:
> >> The function is adding the value of two chunks together and returning
> the result. How does that even compute? Unless the + operator is doing
> something totally different here…
> >
> > The code said:
> >
> >> sort lines tVariable by myVal(each)
> >>
> >> where the function is for example
> >>
> >> function myVal pStr
> >>    return item 1 of pStr + item 2 of pStr
> >> end myval
> > since it's sorting the lines of the container, it calls the custom
> function with each line in turn. The function simply adds together the
> first two items from the passed-in line, and returns that. The returned
> value is associated with the corresponding line - and then the container is
> sorted by those associated values.
> >
> > This works fine if the input variable is well formatted (i.e. first and
> second items of each line are numeric), but fails to give an error when
> something goes wrong - such as a non-numeric item.
> >
> > (and, yes - the dictionary description is misleading, if not simply
> incorrect. However, the "Tip" at the end describes the use of ustom
> functions).
> >
> > Alex.
> >
> >
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