Using tied hashes, you could conceivably make your own ordered hash class
and use that as the data structure you return. You'd still basically have
two data structures (for performance) but the fact that it is two data
structures would be hidden behind the tied hash which would be programmed
to iterate the keys using the array rather than the keys function on the
hash part.
I think there is source code for this publicly available, but I forget
where I saw it. You can get some docs from perldoc perltie though.
At 12:39 PM 6/6/00 -0400, Drew Taylor wrote:
>Hello,
>
>This doesn't directly relate to mod_perl, but I'd like to make this as
>memory efficient as possible since it runs under mod_perl. :-)
>
>I have a question about data structures. Currently, I am doing SQL
>queries and returning an array ref and a hash ref. The array is to
>preserve order, and the hash contains various bits of data about that
>particular product ( it could be another hash ref, and often is). After
>getting the two references, I use foreach to loop through the array, and
>within that loop I access various data from the hash where the productID
>is the key. It looks like this:
>
>Common.pm:
>sub getdata {
> my $AR = [123, 456, 243, ... ]
> my $HR = { 123 => {foo=>bar, name=>'name', price=>'123'}, ... }
> return ($AR, $HR);
>}
>
>Otherstuff.pm:
>my ($AR, $HR) = $self->getdata();
>foreach (@{$AR}) {
> my $name = $HR->{$_}{name};
> ...
>}
>
>I would like to return a single data structure, but order IS important
>(hence the current setup). I was thinking of using an array, where each
>element is a hash reference. So I would return something like this:
>
>[ {ID=>123, name=>'name123', foor=>'bar'}, {ID=>321, name=>'name321',
>bar=>'foo'}, ... ]
>
>Are there any de-referenceing issues (performance wise) that would make
>this less efficient than the 2 structures? TIA for any pointers.
>
>--
>Drew Taylor
>Vialogix Communications, Inc.
>501 N. College Street
>Charlotte, NC 28202
>704 370 0550
>http://www.vialogix.com/
