Data::Clone - Polymorphic data cloning

       Goro Fuji (gfx) <gfuji(at)cpan.org>

       No bugs have been reported.

       Please report any bugs or feature requests to the author.

       Perl 5.8.1 or later, and a C compiler.

       "Data::Clone" does data cloning, i.e. copies things recursively. This is smart so that it works with not
       only non-blessed references, but also with blessed references (i.e. objects). When clone() finds an
       object, it calls a "clone" method of the object if the object has a "clone", otherwise it makes a surface
       copy of the object. That is, this module does polymorphic data cloning.

       Although there are several modules on CPAN which can clone data, this module has a different cloning
       policy from almost all of them.  See "Cloning policy" and "Comparison to other cloning modules" for
       details.

   Cloningpolicy
       A cloning policy is a rule that how a cloning routine copies data. Here is the cloning policy of
       "Data::Clone".

       Non-referencevalues

       Non-reference values are copied normally, which will drop their magics.

       Scalarreferences

       Scalar references including references to other types of references are not copied deeply. They are
       copied on surface because it is typically used to refer to something unique, namely global variables or
       magical variables.

       Arrayreferences

       Array references are copied deeply. The cloning policy is applied to each value recursively.

       Hashreferences

       Hash references are copied deeply. The cloning policy is applied to each value recursively.

       Glob,IOandCodereferences

       These references are not copied deeply. They are copied on surface.

       Blessedreferences(objects)

       Blessed references are not copied deeply by default, because objects might have external resources which
       "Data::Clone" could not deal with.  They will be copied deeply only if "Data::Clone" knows they are
       clonable, i.e. they have a "clone" method.

       If you want to make an object clonable, you can use the clone() function as a method:

           package Your::Class;
           use Data::Clone;

           # ...
           my $your_class = Your::Class->new();

           my $c = clone($your_object); # $your_object->clone() will be called

       Or you can import data_clone() function to define your custom clone method:

           package Your::Class;
           use Data::Clone qw(data_clone);

           sub clone {
               my($proto) = @_;
               my $object = data_clone($proto);
               # anything what you want
               return $object;
           }

       Of course, you can use Clone::clone(), Storable::dclone(), and/or anything you want as an implementation
       of "clone" methods.

   Comparisontoothercloningmodules
       There are modules which does data cloning.

       "Storable" is a standard module which can clone data with dclone().  It has a different cloning policy
       from "Data::Clone". By default it tries to make a deep copy of all the data including blessed references,
       but you can change its behaviour with specific hook methods.

       "Clone" is a well-known cloning module, but it does not polymorphic cloning. This makes a deep copy of
       data regardless of its types. Moreover, there is no way to change its behaviour, so this is useful only
       for data which link to no external resources.

       "Data::Clone" makes a deep copy of data only if it knows that the data are clonable. You can change its
       behaviour simply by defining "clone" methods.  It also exceeds "Storable" and "Clone" in performance.

Exportedfunctionsclone(Scalar)

       Returns a copy of Scalar.

   Exportablefunctionsdata_clone(Scalar)

       Returns a copy of Scalar.

       The same as clone(). Provided for custom clone methods.

       is_cloning()

       Returns true inside the clone() function, false otherwise.

       Copyright (c) 2010, Goro Fuji (gfx). All rights reserved.

       This library is free software; you can redistribute it and/or modify it under the same terms as Perl
       itself.

perl v5.40.0                                       2024-10-20                                   Data::Clone(3pm)

       Data::Clone - Polymorphic data cloning

       Storable

       Clone

           # as a function
           use Data::Clone;

           my $data   = YAML::Load("foo.yml"); # complex data structure
           my $cloned = clone($data);

           # makes Foo clonable
           package Foo;
           use Data::Clone;
           # ...

           # Foo is clonable
           my $o = Foo->new();
           my $c = clone($o); # $o is deeply copied

           # used for custom clone methods
           package Bar;
           use Data::Clone qw(data_clone);
           sub clone {
               my($proto) = @_;
               my $object = data_clone($proto);
               $object->do_something();
               return $object;
           }
           # ...

           # Bar is also clonable
           $o = Bar->new();
           $c = clone($o); # Bar::clone() is called

       This document describes Data::Clone version 0.006.