On 12/15/20 11:23 AM, Glenn Jackman wrote:
On 2020-12-11 11:41, Chet Ramey wrote:
I agree that it would be useful to have
foo='1 2'
declare -A v1=$( $foo 3 )
declare -A v2=$( [$foo]=3 )
set the two arrays to the same contents
I would think that these pairs of invocations would correspond:
declare -A v1=$( $foo 3 )
declare -A v1=$( [1]=2 [3]="")
declare -A v1=$( "$foo" 3 )
declare -A v1=$( ['1 2']=3 )
Do word splitting and quote removal not occur within the parentheses of an
_associative_ array definition?
Associative array keys do not undergo word splitting on assignment, whether
they are used in a subscript or the alternate key-value synatx. This has
been the case since their introduction in bash-4.0.
As the manual states:
When assigning to an associative array, the words in a compound assignment
may be either assignment statements, for which the subscript is required,
or a list of words that is interpreted as a sequence of alternating keys
and values: name=(key1 value1 key2 value2 … ). These are treated
identically to name=( [key1]=value1 [key2]=value2 … ).
They do not appear to be treated identically:
$ declare -A name=( [foo]=bar [baz]="hello world" )
$ declare -p name
declare -A name=([foo]="bar" [baz]="hello world" )
but with a key-value list, the quotes are preserved:
$ declare -A name=( foo bar baz "hello world" )
$ declare -p name
declare -A name=([foo]="bar" [baz]="\"hello world\"" )
Yes, this is what I referred to in the message you quoted above.
I'd love to be able to read a key-value list from a CSV file, like
$ line="foo,bar,baz,hello world"
$ enable -f csv csv
$ csv "$line"
$ declare -A assoc
$ assoc=( "${CSV[@]}" )
I understand that. I don't see a clean way to reconcile it with the
restriction that keys don't undergo word splitting.
But, as previously stated, the whole array is taken as a single key
$ declare -p assoc
declare -A assoc=(["foo bar baz hello world"]="" )
There's a workaround using `eval` and shell-quoted transformation,
but ... yuck:
$ eval assoc=( "${CSV[@]@Q}" )
$ declare -p assoc
declare -A assoc=([foo]="bar" [baz]="hello world" )
It is possible, if not quite as elegant as you'd like.
Particularly when this same technique works for indexed arrays: this results in
a copy of the CSV array, not a new array with only a single element:
declare -a copy
copy=("${CSV[@]}")
Yes, indexed arrays and associative array key-value pairs behave
differently. In particular, the keys don't appear in the above assignmnent
at all.
Chet
--
``The lyf so short, the craft so long to lerne.'' - Chaucer
``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU c...@case.edu http://tiswww.cwru.edu/~chet/
