Geometry Boost List: [ggl] space partitioning

Subject: [ggl] space partitioning
From: Simonson, Lucanus J (lucanus.j.simonson)
Date: 2010-09-10 20:22:56

Adam Wulkiewicz wrote:
>> We should steer the discussion of design away from focusing on what
>> is wrong and make constructive suggestions about what good
>> alternatives might be.  Then we can discuss how various design
>> options meet the design goals Adam may have, which is a much more
>> interesting conversation.    
> 
> Maby I'll describe the original idea. There may be a lot of different
> tree structures so I'd like to design a generic tree template which
> might be used as an internal structure of various containers. This
> tree should probably be the intrusive container. Base node structure
> I've used has 4 pointers:
> 
> struct node
> {
>    node *next;
>    node *parent;
>    node *previous_sibling;
>    node *last_descendant;
> };

Sorry, the design doesn't make sense to me.  I don't see the point of any of these four pointers.  Why wouldn't the node just have an array of N child nodes?  Why a base class not and not a template parameter and traits?  If you are inheriting without a virtual destructor people will ask why.  I can't see any answer.  Inheritance requires a strong rationale in boost and Liskov substitution principle gets thrown around a lot.  You never explained how your is_leaf and is_node traits work, but I see no obvious mechanism.

Regards,
Luke