On 2024-04-13 21:57, Bart Schaefer
wrote:
Because zsh does not split parameter expansions by default, $ary and
$ary[*] and $ary[@] are equivalent when not quoted, as Lawrence
demonstrated.
However, in all three of those cases, empty elements are typically
discarded, as they would be in a shell that defaults to splitting.
That's why "$ary[@]" is still useful: It quotes each element
individually, so empty elements are preserved.
(Aside, in bash and ksh, $ary is equivalent to ${ary[0]}, not to
${ary[*]}. A little oddly, this is also true for their associative
arrays, that is, the value for key 0 is used.)
I know it's far too late to fret this stuff, still it's interesting
to contemplate these design level issues. P.F. did the right thing
not splitting by default but he should have left the empties in by
default too, IMHO. Options should be positive not negative as a
fundamental principle. Don't do helpful things automatically, and
force me to stop you from doing them. Much better to leave things
alone, and if I want, say, empty elements removed, I'll ask for them
to be removed. A=B should mean that A is identical to B, not B with
blanks removed, nor sorted, nor capitalized, nor duplicates removed,
nor checked for spelling, nor ... nothing.
"$ary[@]" should be the default with some ${(?)...} flag to indicate
that I'd like blanks removed or duplicates or ... whatever
massaging I'd want. Cool that all those manipulations are available
of course, but as Raymond Sensei (E. S. Raymond) explains so well,
the 'doctrine of least surprise' should prevail. Equals equals
equals, not 'equals minus blanks'. So we have:
aaa=( "${(@f)bbb}" )
... which is code fighting itself. The quotes normally mean 'join
together' but they also mean 'preserve spaces' and so then '(@f)'
contradicts the joining so we retain multiple elements. IMHO it
should look like this:
aaa=( $bbb )
Equals equals equals.
But as we have it:
----------------------------------------------------------------------------------
% print $ddd
abc def ghi jkl mno pqr
% fff=( $ddd )
% print $fff
abc def ghi jkl mno pqr
# Looks ok, donit? But don't be a chump:
% typeset -p ddd; typeset -p fff
typeset -a ddd=( '' abc '' $'\tdef ghi' $'\tjkl mno' '' $'\tpqr'
'' )
typeset -a fff=( abc $'\tdef ghi' $'\tjkl mno' $'\tpqr' )
# It's not a zebra, it's a horse with painted stripes!
# If you want a COPY ... yes, a Xerox copy:
% fff=( "${(@f)ddd}" )
% typeset -p ddd; typeset -p fff
typeset -a ddd=( '' abc '' $'\tdef ghi' $'\tjkl mno' '' $'\tpqr'
'' )
typeset -a fff=( '' abc '' $'\tdef ghi' $'\tjkl mno' '' $'\tpqr'
'' )
# That's a COPY ... and don't even
think about a simpler way, we are on this earth to suffer.
------------------------------------------------------------------------------------
Just sayin', I know there's nothing to be done about it now.