{
  default => {
    'BM_shutts_south_00' => 1,
    'BM_shutt_north_00' => 1, 
  },
};

##</code><code>##


# define %Log_rooms out here, where it will remain in scope:
my %Log_rooms = (
  default => {
    'BM_shutts_south_00' => 1,
    'BM_shutt_north_00' => 1
  }
);

my $return = do $config_file;
if ($return && UNIVERSAL::isa($return, 'HASH')) {
  # we got a hash reference back, so override the defaults:
  %Log_rooms = %$return;
}
else {
  # do whatever you need to do to recover
  warn "Using default values.\n"; 
}