[Gambas-user] Data Structures like C++

[tobi]

On Thu, 24 May 2012, Bruce wrote:
> On Mon, 2012-05-21 at 22:25 +0200, Benoît Minisini wrote:
> 
> > * Tree
> > * Graph
> > 
> > Native implementation of that would be interesting.
> > 
> > Any volunteer? :-)
> > 
> I think trees are easily implemented directly in gambas using Emil's
> suggestions regarding object references as a general n-tree can be
> implemented as a B-tree using something like
>  
>     Class CNode
>         public data as Variant
>         public left as CNode
>         public right as CNode
>     Public Sub PreOrder() as Variant[]
>         blah blah ... etc  according to Mr Knuth
>     End
> 
> where "left" is the first child and "right" is the first sibling.  Read
> Knuth Vol 3 for the truth (I had to go searching through the attic to
> find my copy.)
> 
>         Now Graphs are   M U C H   more interesting!  
>         
>         Someone said that they couldn't think of a use for them.  Well
>         here's one, UML diagrams are all directed graphs. In fact much
>         of OO thinking is actually (mathematically) directed graphs.
>         Nodes and edges. From use cases through structural models,
>         component models, in fact the whole she-bang.
> 
> 
> Getting back to trees. The funny thing is that I had a real need to
> construct a n-tree this week to solve a problem I had with populating a
> gambas treeview from a persistence store where the nodes where out of
> order, i.e. the parents were later in the storage than the children (the
> code is a hack and I choose not to share it.)  Suffice to say that
> Demosthenes original post prompted me to go searching through the attic.
> 
> .. found some interesting stuff, by the way .. (No, lets not go there.)
> 
> Getting back to the point, I think a gb.datastructures component is an
> excellent idea.  I can't help much on the dev side as I'm pretty poor at
> C/C++ (can "read only") and am totally lost with Benoit's macros but I'd
> be willing to put in much effort at testing and proving. Ah! Linked
> lists, how many times have I needed them and built them from scratch.
> 
> Bruce
> 
> 
> 
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Hi,

so what syntax did you desire for an n-tree then? You presented a b-tree above, this appears generic
to me... I certainly lack theory on those things.

But shouldn't it be less annoying to get to level 3 than "Root.left.left.left" ?
There are a lot of purposes and designs of trees (graphs), right? To implement a certain idea would
not be too difficult but instead to implement only one of those as a generic tree (graph) which is
then able to be inherited and specialised, maybe in gambas, - that's what I find difficult (no
wonder without theory).

Regards,
Tobi