4.4 change in behavior from 4.3: how to catch unset when using ${#length}

[L. A. Walsh]

On 4.3 and earlier, at least on arrays, one could have
the illusion of this working w/o complaint -- and returning
0 when the array was 0-len or unset, or the array length,
otherwise:


 echo ${#array[@]:-0}

But I note it only seemed to work in arrays, and in 4.4 gets a
syntax error:

 echo ${#array[@]:-0}  
 bash: ${#array[@]:-0}: bad substitution


Is there any reason why such a syntax wouldn't be workable --
including adding:

echo ${#wordlen:-0}  to allow catching an undefined word?

or is there some other, inline way to do this?

-linda

Re: 4.4 change in behavior from 4.3: how to catch unset when using ${#length}

[L. A. Walsh]

Eduardo Bustamante wrote:

what's wrong with?:
echo ${#array[@]}
It will return:
- With array=(1 2 3) -> 3
- With array=() -> 0
- With unset array -> 0
- With declare -a array -> 0

Seems to do what you're looking for.
  


Not when "-u" is set, which I often have on to help catch misspellings.

set -u
echo ${#array[@]}
bash: array: unbound variable

Compare to:

if [[ ${yesno:-""} == yes ]]; then ... fi

# basically wanting 1 test for members, else return 0

if [[ ${array[@]:-"undef"} != undef ]] && ((${#array[@]}))

tnx,
-l

Re: 4.4 change in behavior from 4.3: how to catch unset when using ${#length}

[Eduardo Bustamante]

what's wrong with?:

echo ${#array[@]}

It will return:

- With array=(1 2 3) -> 3
- With array=() -> 0
- With unset array -> 0
- With declare -a array -> 0

Seems to do what you're looking for.