Re: Negative indexes in ${arr[@]:off:length}

[Maarten Billemont]

On 30/06/11 14:15, Greg Wooledge wrote:
> On Wed, Jun 29, 2011 at 06:41:25PM +0200, Maarten Billemont wrote:
>> For those to whom a cursor between elements seems confusing: think 
of your prompt's cursor and imagine an element is a single character.
>
> No wonder this makes no sense to me.  Have you actually looked at the
> cursor in a terminal?  I use rxvt, but xterm is the same: the cursor is
> a black[1] rectangle that *overlies* one of the characters, not a skinny
> little wedge/line that sits *between* characters.
>
> The only time I've ever seen a cursor that is *between* characters is
> in GUI stuff, like a textarea in Firefox.  But for people like me,
> that's the oddball case, not the norm.  I certainly wouldn't expect a
> programming language to work like this.
>
> [1] Or white, if you are one of those people who use a dark background.
> Or possibly amber or green, if you're *really* old school.

My cursor is also a block, but perhaps you use vim.  Write abcabc in a 
vim document, then select the second a.  You move your cursor so that 
the block is on the a or the line is in front of it.  You go into visual 
mode and go forward by one.  ${arr[@]:0:1}.

Now instead of going forward, go backward one (${arr[@]:0:-1}) and 
you'll have selected the c.

It really doesn't matter whether your cursor is a block or a line.  To 
select elements from a set, you need a starting point and a direction, 
and IMO, pretending that ${arr[@]:0:1} should be the same thing as 
${arr[@]:0:-1} is by far the more confusing way to think about arrays.