Dump, Dup or Copy an object

turo has asked for the wisdom of the Perl Monks concerning the following question:

Hi, monks!

I'm wondering if some of you know if exists an effective trick for copying a hash. I mean, does exists some method that allows to duplicate a hash or an array, entirely, creating new references when necessary (not copying the references)? ... (difficult to explain ...)

For example, if i have this array:

@a = ([1,2,3],[a,b,c]);
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Which is compossed by two references to other arrays (ARRAY(0x814cc20), ARRAY(0x819eae0)) p.e.
I want to make a new copy of that array, and a new copy of each sub-element referenced, with the same content.

(ARRAY(0x814aaaa), ARRAY(0x819bbbb))
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Dumping the element to a file, and re-reading is the only way? ... or does it copy the references to a file, so when you load it, perl can allocate the elements on the same memory position? ...
In c++, for make a copy of an object programmers must implement the copy constructor ... I think, i can do the same in perl (with little problems like, how can I allocate new memory, or how can I make the same as memcpy ... bad habits ^_^>), but after, i've saw the power of the Dumpvalue module ... i cant think in other way to do it ...

Thanks, :-)

turo

perl -Te 'print map { chr((ord)-((10,20,2,7)[$i++])) } split //,"turo"'

Comment on Dump, Dup or Copy an object Select or Download Code

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Re: Dump, Dup or Copy an object by holli (Abbot) on Feb 22, 2006 at 13:13 UTC
What you want is called a "deep copy" or "clone". See my node here for some modules that apply here. Update: You might also want to have a look at Class::Cloneable if your structure is actually an object. holli, /regexed monk/	[reply] [d/l]
Re: Dump, Dup or Copy an object by borisz (Canon) on Feb 22, 2006 at 13:33 UTC
My choice would be Storable's `dclone` function. Boris	[reply]
Re^2: Dump, Dup or Copy an object by turo (Friar) on Feb 22, 2006 at 15:06 UTC
`map {thanks} qw(`arkturuz borisz holli`);` The Storable module is what i need (i think so, after reading the pod): `# Deep (recursive) cloning $cloneref = dclone($ref);` [download] ummm, The Class::Cloneable, is cool, but remembers me c++ and the copy constructor, maybe i'll consider to use it soon ... :-) . And, at last the powerfull Data::Dumper is too complex, i suppose, for what i wantted to do (indeed, i don't know what to do with it ^_^> ... by the momment), ... Cheers `perl -Te 'print map { chr((ord)-((10,20,2,7)[$i++])) } split //,"turo"'`	[reply] [d/l] [select]
Re^3: Dump, Dup or Copy an object by holli (Abbot) on Feb 22, 2006 at 15:30 UTC
Out of curiosity i benchmarked it and got the following results: use Benchmark qw(timethese); use Clone; use Storable; #use Scalar::Util::Clone; my $struct = { 'foo' => 'bar', 'move' => 'zig', bar => [1, 2, 3] }; timethese ( 500000, { 'Clone' => sub { my $s = Clone::clone($struct) + }, #'Scalar::Util::Clone' => sub { my $s = Scalar::Util::Clone::c +lone ($struct) }, 'Storable' => sub { my $s = Storable::dclone ($stru +ct) } } ); #Benchmark: timing 500000 iterations of Clone, Storable... # Clone: 3 wallclock secs ( 4.28 usr + 0.00 sys = 4.28 CPU) @ 1169 +04.37/s (n=500000) # Storable: 74 wallclock secs (69.62 usr + 0.03 sys = 69.65 CPU) @ 7 +178.65/s (n=500000) [download] The reason because Scalar::Util::Clone is commented out is that I couldn't make it compile nor did I find a ppd for it. Maybe someone else can step in? holli, /regexed monk/	[reply] [d/l]
Re^4: Dump, Dup or Copy an object by turo (Friar) on Feb 22, 2006 at 16:09 UTC
Re^2: Dump, Dup or Copy an object by holli (Abbot) on Feb 22, 2006 at 13:56 UTC
Dumping the element to a file, and re-reading is the only way? The OP is already aware of Data::Dumper. Update: Sorry Boris, my bad. This was of course meant to be a reply to arkturuz' node above. holli, /regexed monk/	[reply]
Re^3: Dump, Dup or Copy an object by borisz (Canon) on Feb 22, 2006 at 13:59 UTC
??? Boris	[reply]
Re: Dump, Dup or Copy an object by arkturuz (Curate) on Feb 22, 2006 at 13:23 UTC
Also have a look at Data::Dumper.	[reply]


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