Re^3: Get record separator of a file

[karlgoethebier]

in reply to Re^2: Get record separator of a file
in thread Get record separator of a file

OK, I will try my best to explain.

I can see the recsep of a file with:

Karls-Mac-mini:Desktop karl$ hexdump -c -n 8 file.txt 
0000000   f   o   o   ;   b   a   r  \n                               
+ 
0000008

Or i hope so.

But i really don't want to check it this way.

I have many larger files with \r\n or \n as recsep.

So i thought about efficiency and figured out that Tie::File is faster than IO::File for my needs (i benchmarked it, but that is another issue).

But when i tied my @array to the original file, all data was put into the first slot of my @array. After setting the recsep option of Tie::File to \n, everything was good.

So i thought, it would be a good idea to do something like the hexdump command in perl to get the recsep - without loosing the performance boost that Tie::File gives me.

I hope very much that this is a better explanation about what i wanted to do.

Thank you very much for your patience and help.

Regards, Karl

[davido]

Now we're getting somewhere (I think). You should be able to take advantage of Perl's :crlf IO layer to handle the problem for you. I'll let you test this yourself I've tested this, and here is how I think it would work out.

First, Tie::File seems to be "layers" unaware, which is fine, except that you'll have to open the file explicitly, and close it again when you're done, rather than letting Tie::File handle those operations. This gives you control over what layers are applied to the file handle.

use strict;
use warnings;
use Tie::File;
use Scalar::Util qw( weaken );

open my $fh, '+<:crlf', 'filename.ext' or die $!;
my @array;
my $t = tie @array, 'Tie::File', $fh;
weaken $t;  # tie holds its own ref. We don't want a mem leak.
# Work, work, work...
untie @array;
close $fh or die $!;

The relevant explanation of ':crlf' from the POD is: " On read converts pairs of CR,LF to a single "\n" newline character. On write converts each "\n" to a CR,LF pair." Since this happens behind the scenes, it should play nice with Tie::File, but I would test on some copies of the files first to be sure.

Updated: Added weaken to eliminate a potential memory leak, since tie also holds a ref to its own object.

[karlgoethebier]

Update:

Sorry, i saw it to late. Cool, i didn't know this.

Works when called with $fh. Very nice!

Thank you very much and best regards, Karl

[karlgoethebier]

Just thank you very much, Karl