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NAME
Clone::PP - Recursively copy Perl datatypes
SYNOPSIS
use Clone::PP qw(clone);
$item = { 'foo' => 'bar', 'move' => [ 'zig', 'zag' ] };
$copy = clone( $item );
$item = [ 'alpha', 'beta', { 'gamma' => 'vlissides' } ];
$copy = clone( $item );
$item = Foo->new();
$copy = clone( $item );
Or as an object method:
require Clone::PP;
push @Foo::ISA, 'Clone::PP';
$item = Foo->new();
$copy = $item->clone();
DESCRIPTION
This module provides a general-purpose clone function to make deep
copies of Perl data structures. It calls itself recursively to copy
nested hash, array, scalar and reference types, including tied variables
and objects.
The clone() function takes a scalar argument to copy. To duplicate
arrays or hashes, pass them in by reference:
my $copy = clone(\@array); my @copy = @{ clone(\@array) };
my $copy = clone(\%hash); my %copy = %{ clone(\%hash) };
The clone() function also accepts an optional second parameter that can
be used to limit the depth of the copy. If you pass a limit of 0, clone
will return the same value you supplied; for a limit of 1, a shallow
copy is constructed; for a limit of 2, two layers of copying are done,
and so on.
my $shallow_copy = clone( $item, 1 );
To allow objects to intervene in the way they are copied, the clone()
function checks for a couple of optional methods. If an object provides
a method named "clone_self", it is called and the result returned
without further processing. Alternately, if an object provides a method
named "clone_init", it is called on the copied object before it is
returned.
BUGS
Some data types, such as globs, regexes, and code refs, are always
copied shallowly.
References to hash elements are not properly duplicated. (This is why
two tests in t/dclone.t that are marked "todo".) For example, the
following test should succeed but does not:
my $hash = { foo => 1 };
$hash->{bar} = \{ $hash->{foo} };
my $copy = clone( \%hash );
$hash->{foo} = 2;
$copy->{foo} = 2;
ok( $hash->{bar} == $copy->{bar} );
To report bugs via the CPAN web tracking system, go to
"http://rt.cpan.org/NoAuth/Bugs.html?Dist=Clone-PP" or send mail to
"Dist=Clone-PP#rt.cpan.org", replacing "#" with "@".
SEE ALSO
For a faster implementation in XS, see the clone entry in the Clone
manpage, the clone entry in the Util manpage, or <Storable/dclone>.
CREDITS AND COPYRIGHT
Developed by Matthew Simon Cavalletto at Evolution Softworks. More free
Perl software is available at "www.evoscript.org".
Copyright 2003 Matthew Simon Cavalletto. You may contact the author
directly at "evo@cpan.org" or "simonm@cavalletto.org".
Code initially derived from Ref.pm. Portions Copyright 1994 David Muir
Sharnoff.
Interface based by Clone by Ray Finch with contributions from
chocolateboy. Portions Copyright 2001 Ray Finch. Portions Copyright 2001
chocolateboy.
You may use, modify, and distribute this software under the same terms
as Perl.
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