# Sorts files in $dir and sets $latest->{file} with newest file and sets $oldest->{file} with oldest file.
my ( $latest, $oldest ) = (
    sort { $a->{ mtime } <=> $b->{ mtime } }
    map { { mtime => -M $_, file => $_ } }
    <$dir/*>
    )[ 0, -1 ];

my ( $newM, $oldM ) = map +( stat )[ 9 ], $latest->{ file }, $oldest->{ file };