Re: Inheritance in Hash

How do you like the folowing?

use strict;
use warnings;

sub get {
   my $ref = shift(@_);
   my $key = shift(@_);
   my $val;

   for (;;) {
      last unless UNIVERSAL::isa($ref, 'HASH');
      
      $val = $ref->{$key}
         if exists $ref->{$key};

      last unless @_;
      my $branch = shift(@_);
      $ref = $ref->{$branch};
   }

   return $val;
}

my $data = {
   Colour  => 'blue',
   Entries => {
      Flowers => {
         Dahlia => { Smell  => 'nice' },
         Rose   => { Colour => 'red'  },
      },
   },
};

print
   get($data, 'Colour', qw( Entries Flowers Rose   )), $/,  # red
   get($data, 'Colour', qw( Entries Flowers Dahlia )), $/;  # blue
[download]

If $data was blessed to the package which contained get, you could improve the syntax a bit:

print
   $data->get('Colour', qw( Entries Flowers Rose   )), $/,  # red
   $data->get('Colour', qw( Entries Flowers Dahlia )), $/;  # blue
[download]

Comment on Re: Inheritance in Hash Select or Download Code

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Re^2: Inheritance in Hash by ikegami (Patriarch) on Apr 21, 2005 at 03:54 UTC
Here's a version with a better syntax: `# Using "tie". use Tie::Hash::Inheriting (); { tie(my %data, 'Tie::Hash::Inheriting'); %data = ( Colour => 'blue', Entries => { Flowers => { Dahlia => { Smell => 'nice' }, Rose => { Colour => 'red' }, }, }, ); print $data{'Entries'}{'Flowers'}{'Rose' }{'Colour'}, $/, # red $data{'Entries'}{'Flowers'}{'Dahlia'}{'Colour'}, $/; # blue untie(%data); # Free mem. %data going out of scope is not enough. }` [download] or `# Using objects. use Hash::Inherting (); { my $data = Hash::Inheriting->new(); %$data = ( Colour => 'blue', Entries => { Flowers => { Dahlia => { Smell => 'nice' }, Rose => { Colour => 'red' }, }, }, ); print $data->{'Entries'}{'Flowers'}{'Rose' }{'Colour'}, $/, # red $data->{'Entries'}{'Flowers'}{'Dahlia'}{'Colour'}, $/; # blue }` [download] `Tie/Hash/Inheriting.pm` Read more... (2 kB) `Hash/Inheriting.pm` Read more... (443 Bytes)	[reply] [d/l] [select]
Re^3: Inheritance in Hash by ikegami (Patriarch) on Apr 21, 2005 at 18:45 UTC
bah, there are still memory leaks, I think. `$data{'moo'}{'test'} = { a => 1, b => 2 }; # The following line doesn't free the tied hash # containing a => 1, b => 2 until %data is untied. $data{'moo'}{'test'} = 'foo';` [download]	[reply] [d/l]