while ( <$handles[ 3 ]> ) {
  # do something with last line read
}

##</code><code>##

while ( defined( my $line = $handles[ 3 ]->getline ) ) {
  # do something with $line
}

##</code><code>##

frobnicate( $handles[ 3 ]->getline ) until $handles[ 3 ]->eof;

##</code><code>##

my $tmp = $handles[ 3 ];
while ( <$tmp> ) {
  # go crazy
}