Strange re-initialization of array. Bug or feature?

[Tim Friske]

Hi folks,

I execute the following code with Bash version "GNU bash, Version
4.2.39(1)-release (x86_64-redhat-linux-gnu)" on Fedora 17:

# Returns 0 else 1 if the sourcing (source) script isn't keyed by its base
name in the global "ONCE" array yet.
#
# A script should include this script near the top with "source me_once ||
return 0" in order to get sourced itself only
# once.
#
# @return 0 on success, n != 0 on failure.
#
function me_once {
  unset -f me_once
  if [[ ! -v ONCE ]]; then
    echo AAA
    declare -gAi ONCE=()
  fi
  echo BBB
  declare -p ONCE
  declare -r a="${BASH_SOURCE[2]##*/}"
  if (( ${ONCE[$a]:+1} )); then
    return 1
  else
    ONCE+=(["$a"]=1)
    echo CCC
    declare -p ONCE
  fi
}
me_once

If sourced at least twice from another script I get the following output
printed:

AAA
BBB
declare -A ONCE='()'
CCC
declare -A ONCE='([std.bash]="1" )'
BBB
declare -Ai ONCE='()'
CCC
declare -Ai ONCE='([std.bash]="1" )'

If I remove the initialization "=()" from "declare -gAi ONCE" I get the
following output printed:

AAA
BBB
declare -Ai ONCE='()'
CCC
declare -Ai ONCE='([std.bash]="1" )'
BBB
declare -Ai ONCE='([std.bash]="1" )'

The "declare -gAi ONCE=()" seems to get executed every time although
surrounded by "[[ ! -v ONCE ]]" whereas "echo AAA" within the same if-block
only the first time.

Is this a bug or feature?

Cheers,
Tim


-- 
--
`~~~~°<
C92A E44E CC19 58E2 FA35 4048 2217 3C6E 0338 83FC