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Re: How do I insert a line into a file?

by Juerd (Abbot)
on Mar 31, 2002 at 14:44 UTC ( #155606=note: print w/ replies, xml ) Need Help??


in reply to How do I insert a line into a file?

Dominus, you have again created a GREAT module, and I will surely put it to use very often.

A string cannot be used to store data structures, unless serialized. It would however be great to use this efficient Tie::File together with array or hash references. Because putting the serialization in Tie::File would ruin all non-serializing operation, I thought it would be nice to tie an array and have automatic serialization. I have searched CPAN, but couldn't find a module that does what I want, so I created this quick hack:

package Tie::FreezeThaw; # NOTE: # This is a quick hack and has NOT been tested thoroughly! # NOTE: # You can't use the elements directly as references! # (if @xyzzy is tied, $xyzzy[1][2] won't work. # Use $foo = $xyzzy[1]; $foo->[2] instead.) use FreezeThaw qw(freeze thaw); use base 'Tie::Array'; use strict; sub TIEARRAY { bless $_[1], $_[0] } sub FETCHSIZE { scalar @{ $_[0] } } sub STORESIZE { @{ $_[0] } = $_[1] } sub EXISTS { exists $_[0]->[$_[1]] } sub DELETE { delete $_[0]->[$_[1]] } sub STORE { ($_[2] = freeze $_[2]) =~ s/([^\x20-\x7E])/sprintf "\xFF%02x", $1/ +ge; $_[0]->[$_[1]] = $_[2]; } sub FETCH { (my $foo = $_[0]->[$_[1]]) =~ s/\xFF(..)/chr hex $1/ge; return (thaw $foo)[0]; } 1;
Which allows me to use Tie::File with complexer data structures (of course, entire records will be overwritten, but that's still more efficient than re-writing the entire file) without having to think about the serialization.

use Tie::File; use Tie::FreezeThaw; use strict; tie my @foo, 'Tie::File', 'testfile' or die $!; tie my @bar, 'Tie::FreezeThaw', \@foo; push @bar, [ qw/1..10/ ];
(If there's already a module like my quick Tie::FreezeThaw hack, please let me know)

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