Holli's code has two methods, one to open the file and the rest to return it in chunks.

$reader->open ("/path/to/file.txt");

#iterate
while ( my $chunk = $reader->chunk )
{
    print "$chunk\n****************\n";
}
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while ( my $chunk = $reader->chunk("/path/to/file.txt") )
{
    print "$chunk\n****************\n";
}
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So I moved some code around and got this, which works just fine:

package ChunkReader;

sub new {
    my $class = shift;
    my %args  = @_;
    $args{threshold} = 2048
      unless defined $args{threshold};
    return bless {%args}, $class;
}


sub chunk {
    my $self   = shift;
    unless ( $self->{handle} ) {
        my $file = shift || $self->{file};
        print "Filename is $file\n";
        my $handle;
        open($handle, "<", $file)
          or die "cannot open '$self->{file}\n'";
        $self->{handle} = $handle;
    }
    my $handle = $self->{handle} || die "File not open!\n";
    my $chunk  = $self->{lastline};
    # reset last line
    $self->{lastline} = '';
    while ( $line = <$handle> ) {
        if ( ( length( $chunk ) + length( $line ) ) >
            $self->{threshold} )
        {

         # unless we already read a chunk
         # (when a single line is bigger than the threshold)
            unless ( $chunk ) {

                #return the line
                return $line;
            } else {

                # save the last line for further use
                # and return the chunk
                $self->{lastline} = $line;
                return $chunk;
            }
        } else {

            # append line and keep going
            $chunk .= $line;
        }
    }

    #end of file
    return $chunk;
}
1;
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