my @a=(qw(w1 w2 w3),"[t4 w4]" ,qw(w5 w6)); 
  m/\[(\S+)\s(\S+)\]/ ? print qq[$2 $1\n] :print qq[$_\n] for @a

##</code><code>##

my @a=(qw(w1 w2 w3),["t4","w4"],qw(w5 w6));

ref $_ ? print "$_->[1] $_->[0]\n" :print qq[$_\n] for @a