Re: status on $[arith] for eval arith vsl $((arith))??

Chet Ramey wrote:

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Well, I think you are probably right -- looks like alot of newer more
bash-specific, and 'clever' code uses (())...  but it isn't easy on the eyes...


But the examples of use of $(()) are leaning far more toward the perverse side
than simple use of $[]...

Maybe lisp programmers prefer (())??

a few examples:


- options="$(expr "${options}" : "\(.\{$((${last_option_index}-1))\}\)")"
- YESTERDAY=$(date -r $((`date +%s` - 86400 )) +%d/%m/%Y
- PREGAP=$(($(echo $OFFSETS | cut -f1 -d' ')))

- for ((vl=$((v_level - 1)); $vl > 0; --vl))

Using [] in expressions provides a distinct visual feature that is
different from the content....   There's no unclarity in confusing it
with $(xxx) $((xxx)) if xxx is a var and a function, which did they mean?

You don't hae that issue with $[], as to confuse it with an array, you'd
have to leave off the array name and the curly brackets...
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Maarten Billemont wrote:

 > (Don't give

 >  me the spiel about how [...] is already arithmetic evaluation
 > inside array indices, that's a different syntax  entirely,

How is that?  I thought it WAS the syntax.

${xxx[yyy]}  => remove the array base, and you just get a calculated
offset as a result

=> $[yyy]...

It is similar to C in that regard.   You can put [xxx] after an ID, and it
means it is an array # of items past the array's start.  but if the array was
missing.  (well besides the syntax errors), it would just be the offset.



 >>> BTW, in case there is any doubt, I am not pushing for removal of $(()), or
a change of the status quo, but I am taking issue with the idea of removing $[],
as some proposed...




====


> Now, it's hardly any problem to keep dragging the $[...] syntax along.
> It takes only a few dozen bytes of code.  I have no plans to remove it.
> But let's not kid ourselves: it's revisionist history to think that
> $[...] was widespread before Posix so callously stamped it out.

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        I've seen it more often in portable code than the $(()) -- but I
could be remembering it more because it stands out too...


>
>> Geez.
>
> Indeed.

>

        Indubitably.
:-)