man Clone::PP (3): 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 "@".

REPOSITORY

<https://github.com/neilbowers/Clone-PP>

AUTHOR AND CREDITS

Developed by Matthew Simon Cavalletto at Evolution Softworks. More free Perl software is available at "www.evoscript.org".

COPYRIGHT AND LICENSE