# recursively operate on files

use DirHandle;

sub go_in
{ 
    my $dir  = shift;

#  -- this just flips the toothpicks, in case
#    we're in windows.  It's not really necessary.
    $dir =~ tr/\\/\//;

#  -- and this just adds a trailing slash, for
#  concatenating later.
    if ($dir !~ m/\/$/){
      $dir .= '/';
    }

    my $dh   = new DirHandle ($dir);

# or die, I suppose.
    return unless $dh;

    while ( defined( my $item = $dh->read )) {

        next if $item =~ m/\.$/;

        $item         = $dir.$item;

# paranoid about symlinks.
        next if -l $item;

#  -- call recursively, but not forever: 
#     (discard visited directories)

       if ( -d $item ){ 
            go_in($item); 
            next;
       }
#  -- operate on files here             -- #
    
    }

}