http://www.perlmonks.org?node_id=989657

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

Hi Monks

Is there an idiomatic way to add key/value pairs to a hash of anonymous hashes? For example, if I already have: 

my %hoh;
$hoh{element1} = {start => 1,
                  middle => 5};

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but then I want to add an  end => 10 to the same anonymous hash without replacing what's already there. I guess the problem is that the hash, being anonymous, doesn't have a name through which I can access it (other than with  keys  %hoh -- or does it?). So I can extract the anonymous hash to the top level, add to it, then replace what used to be there like so:

my %temphash = %{$hoh{element1}};
$temphash{end} = 10;
$hoh{element1} = \%temphash;

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but I was wondering if there is a better, more standard, idiomatic way to do this?

Thanks in advance...

Dlamini

Replies are listed 'Best First'.
Re: Adding to hash of hashes
by 2teez (Vicar) on Aug 24, 2012 at 23:56 UTC

    but then I want to add an end => 10 to the same anonymous hash without replacing what's already there

    use warnings;
use strict;
use Data::Dumper;

my %hoh;
$hoh{element1} = {start => 1,
                  middle => 5};

print Dumper \%hoh;

 $hoh{element1}{end}=10;  # add to hash

print Dumper \%hoh;

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    OUTPUT: 
    $VAR1 = {
          'element1' => {
                          'middle' => 5,
                          'end' => 10,
                          'start' => 1
                        }
        };

    [download]
    For more information, please check the following: perldsc, perlref, perllol, perldata, perlobj

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[d/l]
[select]
[reply]

      Thanks, 2teez, that's exactly what I was looking for - I think I tried something similar but must have got the syntax wrong somewhere

[reply]
Re: Adding to hash of hashes
by Anonymous Monk on Aug 25, 2012 at 00:15 UTC
    Or, maybe: 
    use warnings;
use strict;
use Data::Dumper;

my %hoh;
$hoh{element1} = {
                  start  => 1,
                  middle => 5
                 };

my @append = (
              {
               test => 1,
               key  => 3
              },
              {
               abc => 2,
               xyz => 5
              }
             );

@{$hoh{element1}}{map keys %{$_}, @append} = map values %{$_}, @append
+;

print Dumper \%hoh;

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[reply]
[d/l]
Re: Adding to hash of hashes
by Anonymous Monk on Aug 25, 2012 at 07:12 UTC
[reply]

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