Is this right? test -v $hash{defined_value} == false?

[Linda Walsh]

>  set -A hash
>  hash=([defined_value]=22)
>  echo ${hash[defined_value]}
22
>  [[ -v ${hash[defined_value]} ]] && echo pass
>  [[ -v ${hash[defined_value]} ]] || echo fail
fail
>  [[ -v {hash[defined_value]} ]] || echo fail  
fail
>  [[ -v hash[defined_value] ]] || echo fail 
fail
[[ -v \${hash[defined_value]} ]] || echo fail
fail
>  echo $BASH_VERSION
4.2.45(1)-release


How do I test if a value is defined in a hash?

This seems more messy and isn't -v supposed
to help clean up such things?
>  [[ ${hash[defined_value]:-""} ]] || echo fail  #it passes
>  [[ ${hash[defined_value1]:-""} ]] || echo fail
fail

So why no '-v'??  :-(