Hi all,

I'm trying to write a kind of wrapper for Tie::File to allow it to manage different data formats (not only lines, or simple paragraphs). The idea is to access data records from a file as if they were in an array.

So far, the module looks like this:

package Tie::File::AnyData;

use strict;
use warnings;

use Tie::File;

sub TIEARRAY
  {
    my ($pack,$file,%opts) = @_;
    if (defined $opts{'code'}){
      my $code = $opts{'code'};
      delete $opts{'code'};

      *Tie::File::get_next_rec = $code;

      no warnings 'redefine';
      *Tie::File::_read_record = sub {
    my ($self) = @_;
    my $rec;

    $rec = Tie::File::get_next_rec ( $self->{'fh'} );
    return $rec;
      }
    }
    Tie::File::TIEARRAY("Tie::File",$file,%opts);
  }

1;
[download]

The idea is to pass an anonymous subroutine that is able to retrieve the data from the file one record by one. Then, we redefine the original _read_record subroutine (that is present in Tie::File) to use this code.

This module can be used, for example, in the following way:

use Tie::File::AnyData;
my $coderef = sub{
  ## Code to retrieve one by one the records of a given format
};
tie my @data, 'Tie::File::AnyData', $file, code => $coderef;
## Use the tied array
[download]

The code seems to work ok (as far as my tests can tell), but has one big limitation: you can not work with 2 data formats at the same time, because a second call to "tie" will override the get_next_rec subroutine:

my $format1 = sub {
  ## Subroutine that reads records with format 1
}
my $format2 = sub {
  ## Subroutine that reads records with format 2
}
tie my @dataf1, 'Tie::File::AnyData', $file_format1, code => $format1;
+ ## Creates get_next_rec and redefines _read_record
tie my @dataf2, 'Tie::File::AnyData', $file_format2, code => $format2;
+ ## Re-defines get_next_rec!!
[download]

I think that this can be solved with some kind of polymorphism, but I don't know exactly how. Any suggestion in solving this would be highly appreciated

Thanks in advance!

citromatik

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