Re^3: Tie::File failing with Unicode/UTF-8 encoding?

[HelenCr]

remiah: I studied your module and test script: you've done a very good job - it's working. Thank you for that.

But, what this effectively does (as UNK noted in his answer here: http://stackoverflow.com/questions/13209474/ ), is re-encoding the data before inserting it into the tied array and the tied file; so the array does not contain Unicode data in internal Perl representation, but instead simply contains the imported UTF-8 strings.

Now in my project, I am doing regex comparisons and substitutions against the tied array; so if I go this route, I'll have to re-decode the array element before any processing, and re-encode it again.

What do you think?

Many thanks for your well-thought-out answer.

Helen

[remiah]

Hello, HellenCr.

I have read Unk's post at stackoevrflow. This is not trivial problem for me having been troubled and struggled with encoding/decoding issue for a long time. It seems Glu monks not noticing this thread...

Unk says

1. Encode manually before handing off to the tied array
2. Figure out what the issue is with Tie::File

No 1 must be like mine, wrapping Tie::File with accessor methods. For No.2, I wish some superior monks pursuit whether it is really seek problem, as Unk says. And there could be No.3 using DB_File module.

#!/usr/bin/perl
# DB_File example from http://blog.livedoor.jp/dankogai/archives/51500
+530.html
use 5.010;
use strict; use warnings; use utf8;
use Fcntl;
use DB_File;
use DBM_Filter;

my @Tied;
my $Filename='087.txt';
my $db = tie @Tied, 'DB_File', $Filename, O_CREAT | O_RDWR, 0644, $DB_
+RECNO;
$db->Filter_Push('encode' => 'UTF-8');

binmode STDOUT,':encoding(UTF-8)';

my $i =0;
while (<DATA>) {
    chomp;
    $Tied[$i] = $_;
    ++$i;
} # end while (<DATA>)

$i =0;
foreach (@Tied) {
    say "$i $Tied[$i]" if /&#964;/;  #greek letter...
    ++$i;
} # end foreach (@Tied)

$db->Filter_Pop();
untie $Filename;

__DATA__
your greek input

Referenced page written in Japanese. Filter_Push seems working fine for me... but it is really greek for me.

regards.

[HelenCr]

Remiah: thank you for your latest post - it's great, I learned a lot from it.

But, there is still a little problem. Consider the following script:

use strict;  use warnings;
 use 5.014;    
 use Win32::Console;
 use autodie; 
 use warnings qw< FATAL utf8 >;
 use Carp;  use Carp::Always;
 use utf8;
use Fcntl;
use DB_File;
use DBM_Filter;

my ($i, $FileName);
my (@Tied);
binmode STDOUT, ':encoding(UTF-8)';
binmode STDERR, ':encoding(UTF-8)';
binmode $DB::OUT, ':encoding(UTF-8)' if $DB::OUT; # for the debugger
Win32::Console::OutputCP(65001);         # Set the console code page t
+o UTF8

$FileName = 'E:\\My Documents\\Technical\\Perl\\Eclipse workspace\\Wor
+k\\'Tie File test.txt';
my $db = tie @Tied, 'DB_File', $FileName, O_CREAT | O_RDWR, 0644, $DB_
+RECNO;
$db->Filter_Push('encode' => 'UTF-8');

while (<DATA>) {
    push @Tied, $_;
} # end while (<DATA>) 

$i =0;
foreach (@Tied) {
    print "$i $_";
    ++$i;
} # end foreach (@Tied)
$db->Filter_Pop();
untie $FileName;
__DATA__
&#964;&#953; &#954;&#940;&#957;&#949;&#964;&#949;;
&#960;&#940;&#961;&#964;&#949; &#964;&#959; &#942; &#945;&#966;&#942;&
+#963;&#964;&#949; &#964;&#959;
&#1513;&#1500;&#1493;&#1501; &#1495;&#1489;&#1512;&#1497;&#1501;
abc &#1500;&#1488; &#1499;&#1503;&#1499;&#1503; efg
&#1502;&#1514;&#1497; &#1493;&#1500;&#1488;&#1503; This is it
&#1502;&#1506;&#1499;&#1513;&#1497;&#1493; &#1500;&#1506;&#1499;&#1513
+;&#1497;&#1493; 
&#931;&#942;&#956;&#949;&#961;&#945; &#949;&#943;&#957;&#945;&#953; &#
+932;&#961;&#943;&#964;&#951;
&#920;&#941;&#955;&#969; &#957;&#945; &#966;&#940;&#969;
&#964;&#953; &#954;&#940;&#957;&#949;&#964;&#949;;

(It's practically identical to your latest script). Notice that on purpose, I took away the "chomp" on input to the tied array, and indeed, as you can see from the script print (STDOUT) output, the array members do have "\r\n" terminations.

But, inspecting the saved tied file, it turns out that the records _do_not_ have newlines (or \r\n) terminations!

Why is that, and what should be done? (Maybe something in $db->Filter_Push())? And how?

In addition, can you refer us to a good documentation for DB_File and DBM_Filter modules?

Many TIA

Helen

[remiah]

Hello HelenCR.

I just thought setting bval option would solve this crlf problem, but DB_File allows only one byte for record delimitor (sorry, I didn't know this ...). DB_File document says


Also note that the bval option only allows you to specify a single byte as a delimiter.

So as you say, Filter_Push for crlf will work.


my @Tied;
my $Filename='087.txt';

my $dbh = new DB_File::RECNOINFO ;
$dbh->{bval}="\n";                  #set bval explicitly
my $db = tie @Tied, 'DB_File', $Filename, O_CREAT | O_RDWR, 0644, $dbh
    or die "failed top open $Filename";

#utf8
$db->Filter_Push('encode' => 'UTF-8');

#add crlf filter
$db->Filter_Push(
    Fetch => sub { s/\r\n$/\n/;}, #convert crlf to lf
    Store => sub { $_ .="\r"; },  #add cr
);
# ... same as before

For documents, I like HTML pages of search.cpan.org
DB_File
DBM_Filter
And you will have "t" directory for each modules, which is for testing. Scripts in "t" directory gives me hints for usages.

regards, good luck.