Re^9: trying to decide best data structure for problem at hand.

Yes. dub_hash is a hash. {$name} accesses an element in the hash, creating it if it didn't exist already.

{$name}{$uid} is shorthand for {$name}->{$uid} which implies the value accessed by $name is a hash reference. Again the hash element is generated if it didn't exist already.

= {...}; is an annonymous hash whose reference is assigned to the element accessed by {$name}{$uid}.

The result is a HoHoH - hash of hash of hash.

DWIM is Perl's answer to Gödel

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Re^10: trying to decide best data structure for problem at hand. by mikejones (Scribe) on Jan 12, 2007 at 20:46 UTC
`HoH -------- 'jblow' => { 'uid' => '2195', 'gecos' => 'Joe Blow,,,', 'gid' => '20' }, snippet..... ( $name, $p, $uid, $gid, $gecos, $dir, $s ) = split( ':' ); $hash1{$name} -> {'uid'} = $uid; $hash1{$name} -> {'gid'} = $gid; $hash1{$name} -> {'gecos'} = $gecos; HoHoH ---------- $VAR1 = { 'jblow' => { '2195' => { 'gecos' => 'Joe Blow,,,', 'gid' => '20' } } }; snippet...... $hash2{$name}{$uid} = { gid => $gid, gecos => $gecos, };` [download] I am now comparing so I grasp hashes and understand them more, in the first printed dump of HoH, there are 2 hashes called "hash1 and "name". hash1 has a key of name with values of uid,gid and gecos? uid,gid and gecos are accessed only through name, joe blow in this case? In the printed dump of HoHoH, there are 3 hashes called "hash2", "name" and "uid". hash2 has keys of name and uid with values of gid and gecos? gid and gecos are only accessible through hash uid? please provide any corrections. thank you...again and the last ?	[reply] [d/l]

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Re^10: trying to decide best data structure for problem at hand.
by mikejones (Scribe) on Jan 12, 2007 at 20:46 UTC

HoH
  --------
  'jblow' => {
                         'uid' => '2195',
                         'gecos' => 'Joe Blow,,,',
                         'gid' => '20'
                       },

  snippet.....
   
   ( $name, $p, $uid, $gid, $gecos, $dir, $s ) = split( ':' );
    $hash1{$name} -> {'uid'}     = $uid;
    $hash1{$name} -> {'gid'}     = $gid;
    $hash1{$name} -> {'gecos'} = $gecos;

   
   
  HoHoH
----------
$VAR1 = {
          'jblow' => {
                         '2195' => {
                                     'gecos' => 'Joe Blow,,,',
                                     'gid' => '20'
                                   }
                       }
        };

  snippet......
   
    $hash2{$name}{$uid} = {
       gid     => $gid,
       gecos => $gecos,
    };
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