Provided by: libclone-fast-perl_0.97-1build1_amd64 
NAME
Clone::Fast - Natively copying Perl data structures
SYNOPSIS
use strict;
use warnings;
use Clone::Fast qw( clone );
use Data::Dumper;
# Though that may be the easiest thing to do, there
# are also other options:
#
# use Clone::Fast; # While using Clone::Fast::clone
# {
# no strict 'refs';
# *clone = \&Clone::Fast::clone;
# }
#
# eval( "sub clone { Clone::Fast::clone }" );
my $original = bless( { 'a' => [ qw( a b c d ) ] }, 'main' );
my $copy = clone( $original );
# Notice the original and copy are no longer the same,
# although they look exactly the same
print "Different memory segments\n" if ( $original ne $copy );
print "Same structure\n" if ( Dumper( $original ) eq Dumper( $copy ) );
DESCRIPTION
Essentially, this module is a very optimized version of Clone::More. By taking advantage
of one of Clone::More's 'OPTIMIZATION_HACKS' as well as removing all the Pure Perl from
the "More.pm", I was able to gain a lot of speed out of the module. Essentially, though,
the core of the module is exactly as that of Clone::More.
You will see that by useing Benchmark::cmpthese, I ran a simple comparison between
Storable::dclone, Clone::More::clone, and Clone::Fast::clone. You will (should) begin to
see the reason why I loaded this module along side of Clone::More.
Rate Storable Clone::More Clone::Fast
Storable 7552/s -- -39% -59%
Clone::More 12400/s 64% -- -33%
Clone::Fast 18442/s 144% 49% --
For more information relative to the DESCRIPTION of this module, I recommend peeking into
the POD written for Clone::More (I took more time with it ;) )
EXPORT
clone
Clone is the primary function from within the provided module. By passing a scalar
reference to this routine, you will expect to get a returned scalar reference that will no
longer have any reference to the originating reference. However, references deeper into
the structure will still uphold the references within the structure.
Example being:
use Clone::Fast qw( clone );
my $foo = { 'a' => 'b' };
my $bar = { 'a' => $foo, 'b' => $foo };
my $baz = clone( $bar );
print "\$foo and \$bar are different references\n" if ( $foo ne $bar );
print "\$foo->{'a'} and \$bar->{'a'} are different references\n" if ( $foo->{'a'} ne $bar->{'a'} );
print "\$foo->{'a'} and \$foo->{'b'} are the same, however\n" if ( $foo->{'a'} eq $bar->{'b'} );
This makes sense, although this can be modified as well. By using the internal variable,
BREAK_REFS, you are also allowed to break internal references (may break up circular
references, although won't fix the circular reference in the originating reference).
PROGRAMATIC HOOKS
Much like the Perl Storable module (available in all current Perl distributions),
"Clone::Fast" allows for hooks that will be accessed when cloning any object that has a
hook defined. This can be very handy where Inside Out objects would not normally be
cloned. WHHAAATT???? What I mean is, only the reference of an object will be cloned, not
the internal stash of the object. Therefore, accessors that are defined within an inside
out object will not be cloned. There is no real safe way to do this, with the exception
of cloning the entire class stash, breaking more things than it will fix. Again, the
reference of the object will be fully cloned, and the object it's self will be a new
reference, although it will be an empty object. Subsiquently, such as most inside out
objects, the blessed reference is of a scalar type; an integer indicating the object id.
When cloning this, you would end up with two objects of the same type with the same object
id. The hooks have been added in an attempt to prevent this from happening.
CLONEFAST_clone
Again, much like Storable (though a little better, I hope), the function will be called
*AFTER* the clone operation has completed on the object being cloned. The routine will
have two scalar references passed via the stack, representing both the cloned object as
well as the source of the clone. This *should* allow for the programatic manipulation of
the object before it gets returned to the caller, or placed into the refering structure.
As an example, I will use the following object to define a 'hooked' object:
package Hookable;
use strict;
use warnings;
use Clone::Fast qw( clone );
sub new { bless {}, shift }
sub CLONEFAST_clone {
# Where clone is the cloned object from the source, where source
# was the originating reference
my ( $clone, $source ) = @_;
# I am going to pretend the source has a list of defined methods,
# of which I want to clone and transfer to the clone; outside
# of the blessed hash-refrence that is the source of the object
$clone->$_( clone( $source->$_() ) ) for ( qw( get_method_1 get_method_2 get_method_3 ) );
# At this point, the cloned object will also have a set of cloned
# fields from the source. If, by chance, any of the values of the
# defined attribtes are other 'Hookable' objects, the same routine
# will be called on that object as well.
# The API requires me to return the new $clone, this will be returned to
# the caller
return $clone;
}
Using the package from above, I will now use an example of a script where I will
demonstrate how the whole thing comes together:
#!/usr/bin/perl -w
use strict;
use Clone::Fast qw( clone );
my $hookable = Hookable->new();
$hookable->{'hash_stuff'} = 'some value';
my $structure = {
'hookable' => $hookable,
'new' => Hookable->new(),
'deeply' => {
'hookable' => $hookable,
'new' => Hookable->new();
},
};
my $cloned = clone( $sturcture );
This script will demonstrate a number of things. 1.) "Clone::Fast::clone" will,
automagically call the hook on all instances of the Hookable. Though the hash_stuff key
will automatically be cloned before the hook is ever called. Subsiquently, the hashes in
both values of hookable in the hash will be references of one another, though not
references to the originating object. The Hookable->new() object, on the other hand, will
not be referenced to anything of the similar like.
As a secondary note, it was originally thought to allow for hooks to show up before and
after the cloning of the object. Though, that would allow for the full change of the
cloning type; this would be very bad. Also, given that it is somewhat reasonable to
believe hooks will only be used with inside out objects, we can also assume the cloning of
a simple referent will be so lightweight that there will still be the benifit of having
clone hook into the object. If anyone has beef with this paradigm, let me know and I'll
change it.
CONFIGURATION VARIABLES
$Clone::Fast::ALLOW_HOOKS
The "ALLOW_HOOKS" variable will allow for the toggling behavior, telling "Clone::Fast"
to check for hooks when cloning objects. (See "PRGRAMATIC HOOKS" for more details).
The varialble will default to 'on', where "Clone::Fast" will always check each object
for hooks defined within the object.
use Clone::Fast qw( clone );
$Clone::Fast::ALLOW_HOOKS = 1; # No need, this is default
my $object = HasHooks->new();
package HasHooks;
use strict;
use warnings;
sub new { bless {}, shift }
sub CLONEFAST_clone {
my ( $clone, $source ) = @_;
# Re-assigning the reference will now return the reference from the
# C<Clone::Fast::clone> when cloning a HasHooks object, rather than
# a cloned reference to the object.
$clone = { 'object' => $clone };
return $clone;
}
$Clone::Fast::BREAK_REFS
use Clone::Fast qw( clone );
$Clone::Fast::BREAK_REFS = 1;
my $foo = { 'a' => 'b' };
my $bar = { 'a' => $foo, 'b' => $foo };
my $baz = clone( $bar );
print "\$foo and \$bar are different references\n" if ( $foo ne $bar );
print "\$foo->{'a'} and \$bar->{'a'} are different references\n" if ( $foo->{'a'} ne $bar->{'a'} );
print "\$foo->{'a'} and \$foo->{'b'} are no longer the same\n" if ( $foo->{'a'} ne $bar->{'b'} );
You will see that by adding the BREAK_REFS flag, you will change the overall behavior
of the routine. The BREAK_REFS flag must, simply, have truthfullness (as far as Perl
is concerned) in order to be 'on'.
Whereas:
$Clone::Fast::BREAK_REFS = 1;
# Will do the same thing as:
$Clone::Fast::BREAK_REFS = 'yes';
# Will do the same thing as:
$Clone::Fast::BREAK_REFS = ( 2 != 1 );
Albeit handy, this feature may also slow down the module by some degree. Therefore,
there is some flexibility into whether or not you need to use this, and the
functionality can be compiled out of the object; speeding up the cloning ability.
Therefore, Re-compiling the mdule without MINDFUL_REFS will increase the speed of the
module by a degree of 3x! If you KNOW you will never use the $Clone::Fast::BREAK_REFS
and are confident with manually installing Perl modules from source, it is recommended
you do so. There are comments in the XS source that will detail how to do this.
This configuration only applies to the "Clone::Fast::clone" routine.
EXAMPLES
Using Clone::Fast::clone
"Clone::Fast::clone" is an exported routine. You can either use it as such, or simply
call it directly on the package.
Example w/ export:
use Clone::Fast qw( clone );
my $source = { 'a' => 'b' };
my $clone = clone( $source );
Example w/o export
use Clone::Fast;
my $source = { 'a' => 'b' };
my $clone = Clone::Fast::clone( $source );
Using Clone::Fast::(is_)?circular
The "Clone::Fast::(is_)?circular" routines will allow you to test whether or not a
structure contains a ciruclar reference or not.
GOTCHAS/WARNINGS
bless()'ed references (Perl objects)
This module works great for blessed references, how ever the paradigm changes when
trying to clone inside out objects (or Conway's 'flywaight' style of object creation).
Clone does not, nor will not, clone the stash of an object's class; this would break
more than anything. Given this, HOOKS have been provided in order to programatically
handle weird stuff like this. I am hoping applications, developers and all of the
like whom are using inside out objects will know what the heck it is I'm talking about
here. There is a lot more information about this in the PROGRAMATIC HOOKS section.
ithreads
I really have no idea how this will work in a treadded environment. It should be OK,
but there is no development that has taken this into account.
Hooks
Hooks are pretty new, and may have some problems within them. Please, if you find
anything you don't expect; feel free to bug it and I will try to patch it up ASAP.
SEE ALSO
Storable
This will, essentially, do the exact same thing as what this module does. The
difference being that Storable will freeze the chunk of memory you are trying to
clone, and thaw that binary chunk to another piece of memory. This works well, yet is
very slow. Subsiquently, Storable, as of Perl 5.8, is CORE; and may be more trusted
than this :)
Clone
The original concept of "Clone::Fast".
AUTHOR
Trevor Hall, <wazzuteke@cpan.org>
COPYRIGHT AND LICENSE
Copyright (C) 2006-2012 by Trevor Hall
This is free software, licensed under:
The Artistic License 2.0 (GPL Compatible)