in reply to Complex Data Structure Suggestions Wanted

First may I say yours was a well written question, and through your research you'd actually got most of the concepts right.. and were pretty close to an answer!

Because data structures get very complex very fast I almost never use two dollar signs in a row. I always encapsulate in {} braces.

Having the data would have helped a lot. Because I suspect your structure is more complex than my interpretation of your sub-routine.

Just cleaning up the subroutine for my own benefit I would have written:

sub ReadSource( $ $ ) { my $DataSource = shift; my $HashRef = shift; foreach my $ItemID (@Data) { my $data_array_ref = $HashRef->{$ItemID}; if ( $data_array_ref ) { push( @{$data_array_ref}, $DataSource ); } else { $HashRef->{$ItemID} = [ $DataSource ]; } } }

.. but it is more than likely I have misinterpreted something there as I've only allowed for a hash of arrays. IE I'm presuming you would call this something like follows:

my %myhash = (); # empty hash my @Data = ( 'this', 'that', 'that over there' ); my $datasource = 'banana'; ReadSource( $datasource, \%myhash );
which when printed:
use Data::Dumper; ReadSource( $datasource, \%myhash ); print( Dumper( \%myhash ) . "\n" );
.. results in the following output:
$VAR1 = { 'this' => [ 'banana' ], 'that' => [ 'banana' ], 'that over there' => [ 'banana' ] };

update: also as a personal comment I like to use hungarian type notation on complex structures, it can give me an idea of what I'm playing with before I play with it.