Re: set -A

["Bart Schaefer" <schaefer@brasslantern.com>]

On Feb 6,  7:01pm, Paul Ackersviller wrote:
} Subject: set -A
}
} unset arr
} set -A arr "${arr[@]}" first
} [ ${#arr[@]} = 2 ] && echo "arr[0]='${arr[0]}' arr[1]='${arr[1]}'"
} 
} Note the null entry on the start of the array.

This really has nothing to do with "set -A".

If you've unset arr, then arr is not an array, and hence ${arr[@]} is
not an array either, and therefore "${arr[@]}" does not behave like
an array; rather, it behaves like a string, so putting it in double
quotes yields the empty string.

} I believe the above should work as in ksh, and consistently with
} positional parameters

Doesn't follow.  $@ cannot be unset, it can only be set to the empty
array.  This example ...

} set --
} set -A arr "$@" first
} echo arr now has only ${#arr[@]} element

... really corresponds to:

arr=()
set -A arr "${arr[@]}" first
echo arr now has only ${#arr[@]} element

} [...] it'd be nice if it at least worked like ksh in emulation mode.

This is a clash with zsh's usage where subscripts on a string yeild
substring slices.  The substring slice [@] is the entire string, so
${string[@]} == ${string}.  We were under the impression that this
could not possibly clash with a valid ksh script, because no working
ksh script could rely upon subscripting a string.

We may have to rethink that.