Did you even try to read the documentation of Tie::File?

Tie::File represents a regular text file as a Perl array. Each element in the array corresponds to a record in the file. The first line of the file is element 0 of the array; the second line is element 1, and so on.

The file is not loaded into memory, so this will work even for gigantic files.

Changes to the array are reflected in the file immediately.

Lazy people and beginners may now stop reading the manual.

Tie::File has its uses, but of course it introduces some overhead. For some manipulations, the overhead can become a real performance killer.

Alexander

Did you even try to read the documentation...

This question tells me you didn't even try to read what I posted, just the title. It probably wasn't the best title for this node but it was the question I had been wondering until this morning.

#!/usr.bin/perl -l

BEGIN { 
    $| = 1;
    $^W = 1;
}

use strict;
use autodie;
use warnings;

my $file = "file.txt";
1 while unlink $file;

use Tie::File;

my $o = tie my @lines, 'Tie::Tile', $file, memory => 0;
for (@lines) {
    $lines[2] = "something else is here now';
    print $lines[2];
    #line 3 is now "something else is here now".
}

END {
    undef $o;
    untie @lines;
    1 while unlink $file;
    #clears and empties everything.
}
[download]

Having a glitch of some kind---code is coming:). Here:

How delightfully refreshing, here's mine

P.S.

<Reveal this spoiler or all spoilers in this node or all in this thread>

It now runs great!

<Reveal this spoiler>

The output is twice as much

<Reveal this spoiler>

• Using perl -l gives you autochomp which Tie::File has built in. From your other nodes I see you use this frequently to add a newline when you print.
• $^W = 1; and then use Warnings; a few lines later?
• Using autodie means the script stops after the unlink line even if there is a file to delete. Why not just die if -e $file; ?
• Does $| = 1; have any effect on Tie::File? With the option memory => 0 it is already not cacheing anything.

I don't understand the point of this code. Tying to a file that doesn't exist, adding a line, then deleting the newly created file doesn't seem useful.

Thanks for posting but I don't understand the point of this code

It is pointless, he's a troll.

• Re^2: what is the purpose of Tie::File (Khen1950fx ignores question again, then posts baffling code, so I make fun of him)
• Khen1950fx cpan meme, Khen1950fx cpan meme, Khen1950fx cpan meme
• Re: Substring giving strange results on $1 with utf8,(Is this a perl-bug? Khen1950fx will fix it)
• Re: Use 'strftime' to calculate a date/time in the Past.( the only thme Khen1950fx updated his junk to be relevant)
• Re: XML::Twig - how can I test for an attribute when the attribute value is 0? (Khen1950fx copy/pastes some irrelevant code, pretends its an answer, again)
• Re: Can Cache::Memcached::Fast distinguish timeout or not existing? ( yes or no question; Khen1950fx answers with question: something like this? )
• Re: suggested module/tools to automatically "tighten" my perl (Khen1950fx uses a module, then proceeds to copy/paste that modules code)

I haven't had occasion to use it (never written a text-editor) so I never had that need :) but see what the author had to say: Tie::File -> Tie::File, How do I insert a line into a file?

Thanks for the links. Those make it pretty clear how it is useful. Although Perl isn't a text editor I seem to be too often.

On one of the slides in the second link I found this interesting regex. s/^/>> /; Another obvious thing I suppose that I didn't know or realize before: that you can substitute something for nothing and therefore insert something at a boundary.

Yes, or you can substitute something for what may be nothing, as in s/\n*\z/\n/.
--
A math joke: r = | |csc(θ)|+|sec(θ)|-||csc(θ)|-|sec(θ)|| |

Hello

In the thread which reports UTF8 problem of Tie::File, I vaguely imagined a case which sometimes asked in this monk. That is "there is large, large file, and I want to find last 5 records and modify them".

Tie::File, and DB_File could iterate from last records(because it is array), so I thought these could do that kind of jobs faster.

Now I am thinking is there widgets (TK or GTK), using tied array feature? Say, $That_Widget::DATA[0]="new data"; updates file. Or, DBI supports this kind of data access like Tie::File ??? I wonder whether I responded your post ...
regards.