use Fcntl 'SEEK_SET';

$fb->seek( 10, SEEK_SET );
[download]

Thanks for the explanation. But I still get the same error, here is a small test script (called fio.pl):

#! /usr/bin/perl

use strict  ;
use File::Binary ;
use Fcntl 'SEEK_SET'; 

my $fb = File::Binary->new("fio.pl");

$fb->seek(10, SEEK_SET ) ;

$fb->close ;
[download]



Luca

That's because File::Binary's code is wrong. Specifically, the seek() method is written as so:

sub seek {
    my $self = shift;
    my $seek = shift;
    unless ($self->{_is_seekable}) {
        carp "FH is not seekable" if $DEBUG; 
        return 0;
    }

    $self->{_fh}->seek($seek) if defined $seek;
    $self->_init_bits();
    return $self->{_fh}->tell();
}
[download]

Which is wrong. The whole module is written rather sloppily, frankly. Which is not surprising, given that the test suite doesn't even have a test for seek().

Furthermore, the test coverage for the 2874 tests is only

---------------------------- ------ ------ ------ ------ ------ ------
+ ------
File                           stmt   bran   cond    sub    pod   time
+  total
---------------------------- ------ ------ ------ ------ ------ ------
+ ------
blib/lib/File/Binary.pm        79.2   47.6   37.5   87.1   95.0  100.0
+   73.1
Total                          79.2   47.6   37.5   87.1   95.0  100.0
+   73.1
---------------------------- ------ ------ ------ ------ ------ ------
+ ------
[download]

If I were you, I would find some other way to do what you're trying to do.

---

My criteria for good software:

1. Does it work?
2. Can someone else come in, make a change, and be reasonably certain no bugs were introduced?

#! /usr/bin/perl

use strict  ;
use Fcntl 'SEEK_SET'; 
use IO::Seekable;          # not sure if this will help
our @ISA = qw(IO::Seekable);

open IN,"<fio.pl" ;

binmode IN ;

my $reclen = 1 ;
my $binrec ;

while ( read(IN, $binrec, $reclen) ) {
    print "".unpack("A",$binrec) ;
}

....... # seek ?
[download]

Close. Either use the OO approach (by creating an IO::File) or the functional approach, but forget this whole @ISA = qw(IO::Seekable) business.

#! /usr/bin/perl

use strict;
use warnings;

use Fcntl 'SEEK_SET'; 

open local *IN, "<", "fio.pl" ;        # XXX Check for errors

binmode IN ;

my $reclen = 1 ;
my $binrec ;

while ( read(IN, $binrec, $reclen) ) {
    print "".unpack("A",$binrec) ;     # XXX What's with '"".'?
}

seek(IN, 10, SEEK_SET);                # or whatever
[download]

Docs: seek

Thnx, I've fixed it (without OO). If I try OO, like:

#! /usr/bin/perl

use strict  ;
use Fcntl 'SEEK_SET'; 
use IO::File ;

my $fh = new IO::File ;

$fh->open("fio.pl") ;

$fh->binmode() ;
$fh->setpos(4) ;

my $in ;
$fh->read($in,2) ;

printf "result: %s\n",unpack("A2",$in) ;


$fh->close() ;
[download]

The output is: result: #! (thats no shift at all!)
But I get the idea that the biggest mistake has been made with the read command....
Also, what about perldoc IO::Handler:

$io->read ( BUF, LEN, [OFFSET] )
[download]

I miss the explanation of the 3 variables BUF, LEN and OFFSET ?

Thanks
Luca

update: solved the seek issue: $fh->seek(5, SEEK_SET) ;
I guess the only thing I don't understand is the OFFSET. If I give that a number I get nothing... ?