Re: set -A

[Peter Stephenson <pws@xxxxxxx>]

"Bart Schaefer" wrote:
> } But the `@' subscript is not documented to do anything useful for
> } strings
> 
> That's not strictly true.  The docs say, in consecutive paragraphs:
> 
> ----------
> A subscript of the form `[*]' or `[@]' evaluates to all elements of an
> array; there is no difference between the two except when they appear
> within double quotes. [...]
> 
> Subscripting may also be performed on non-array values, in which case
> the subscripts specify a substring to be extracted.
> ----------
> 
> It does NOT say that subscripting non-array values is limited to using
> integer ranges; it just says "subscripting may also be performed."

The simple-minded reading would therefore be that the [@] has the same
behaviour for strings as for arrays --- i.e. whether the parameter
happens to be unset or not, and whether or not KSH_ARRAYS is in effect.
Does that break anything if KSH_ARRAYS isn't set?  (Presumably it
doesn't break anything unless it relies on `undefined behaviour', hur
hur.  But I don't think we can be that sanguine about the zsh
documentation, c.f. hitherto the undocumented set -A behaviour.)

> It's actually worse than that, though, because ksh treats ALL parameters
> as arrays -- in ksh, foo=xyz is the same as foo=(xyz) in zsh, and the
> fiction of string variables is maintained by making $foo a reference to
> ${foo[0]}.  So when KSH_ARRAYS is set, ${foo[1]} (or any number greater
> than zero) ought to produce an empty result when used on a scalar.

Yes, that seems inevitable.

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


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