Re: Error on arithmetic evaluation of `~0`.

From	Chet Ramey <chet.ramey@case.edu>
Newsgroups	gnu.bash.bug
Subject	Re: Error on arithmetic evaluation of `~0`.
Date	2018-12-29 10:46 -0600
Organization	ITS, Case Western Reserve University
Message-ID	<mailman.6526.1546102281.1284.bug-bash@gnu.org> (permalink)
References	<CAFra36gW8Csu-84oRLV7QsR7PbiMYq6g7WnMktjfnrSdTys38g@mail.gmail.com> <25e8adf0-96d5-1e38-faea-e7620ba3f846@case.edu> <CAFra36gzzbJLjqt9OYtJUuJara3KR2+ew-Gj3y2mA2L4X8CRyw@mail.gmail.com> <fc279c3d-35f8-1afa-e515-bfcf2f3bed44@case.edu> <CAFra36htTMBLVXARod9FX__5GY_PXhZ9BJB-Tp5fdiMdGHDx2A@mail.gmail.com>

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On 12/28/18 11:26 PM, Bize Ma wrote:
> Chet Ramey (<chet.ramey@case.edu <mailto:chet.ramey@case.edu>>) wrote:
> 
>     On 12/23/18 12:01 PM, Bize Ma wrote:
> 
> {…}
> 
>     > Both command line above should have printed "hello".
> 
>     No. 0 is the only valid subscript for a non-array variable. The difference
>     between bash and other shells that implement this feature is that bash
>     warns about negative subscripts.
> 
> 
> If you say so: fine for me.
> 
> It still irks me a little that a `${var[-1]}` isn't the "last value"
> (sometimes!, consistency?).

The goal is not to make non-array variables look exactly like array
variables; the goal is to provide a little bit of syntactic sugar in
the rare case that it's useful. It's the analog to referencing an array
variable without using a subscript, which references element 0.

> I haven't seen that documented anywhere, though.

Which part? The fact that non-array variables can be referenced using
subscript 0?

-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
		 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    chet@case.edu    http://tiswww.cwru.edu/~chet/

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Re: Error on arithmetic evaluation of `~0`. Chet Ramey <chet.ramey@case.edu> - 2018-12-29 10:46 -0600

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