Re: set -A

[Peter Stephenson <pws@csr.com>]

Oliver Kiddle wrote:
> I'm inclined to agree that this is wrong. It would seem more logical to
> me for an unset variable to be interpreted as an empty array when
> retrieved in array context. 
>...
> I've been aware of this for some while and had intended to change it if
> I ever have time to finish work on the parameter code. Would changing
> it break much? It would improve bash/ksh compatibility.

I suspect it would improve matters in the particular case of `[@]' --- I
see no occasion when someone would deliberately use that in the
expectation it caused "$foo[@]" to turn into a zero-length string for an
empty $foo of any type.  However, note there is in general no such thing
as `array context' in zsh, so we need to be careful with other subscripts.

> A similar thing which I find annoying is
> that local defines parameters to be scalar by default instead of
> leaving their type undefined causing similar empty element problems.

There's no such thing as an undefined type for a declared parameter,
either, nor is it clear what that would mean.  You have to declare it with
a particular type.  You need to declare it as `local -a' if you want it
to behave as an array.  I think the problem is few people have yet got
into the habit of doing this (though increasing use of += makes it more
necessary).

-- 
Peter Stephenson <pws@csr.com>                  Software Engineer
CSR Ltd., Science Park, Milton Road,
Cambridge, CB4 0WH, UK                          Tel: +44 (0)1223 692070


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