I had to use a complex data structure in a program at work involving hashrefs within arrays within a hash and copying it was a pig because the copied variable contained references to data stored withing the original variable. This led to problems with data corruption and so on. So I came up with deepcopy......

See the difference below. In the first pair %bar contains a pointer to the data contained within %foo but deepcopy seperated the variables.

%foo = (
         'x' => [
                  {
                    'a' => 1,
                    'b' => 2
                  },
                  100
                ]
       );
%bar = (
         'x' => $foo{'x'}
       );
%bim = (
         'x' => [
                  {
                    'a' => 1,
                    'b' => 2
                  },
                  100
                ]
       );
%bom = (
         'x' => [
                  {
                    'a' => 1,
                    'b' => 2
                  },
                  100
                ]
       );

[download]
use Data::Dumper;
use Storable qw(freeze thaw);

# Set up some complex variables, a hash within an array within a hash
my $x = {
    a => 1,
    b => 2,
};

my %foo = (
    x => [$x, 100],
);

# Copy it...
my %bar = %foo;

# Then deepcopy it...
my($bim, $bom) = deepcopy(\%foo, \%bar);

# Then lets have a look inside each variable... ;)
my $dump = Data::Dumper->new([\%foo, \%bar, $bim, $bom], [qw(*foo *bar
+ *bim *bom)]);
print $dump->Dump;


# The sub itself
sub deepcopy {
    my @return;

    # This sub will take any number of references to a variable and
    # parse them all. The result is put into @result and returned as
    # an array
    while(@_) { push @return, thaw freeze shift; }
    return @return;
}

[download]

In reply to deepcopy by Caillte

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