But please notice that FTTreeDataSource is not a ���Tree Structure���, and it is not its purpose��� FTTreeDataSource is a data source :) a provider of data for visualisation purposes, in a tree way. 
This is very different than been a tree structure��� for example, FTTreeDataSource could *contain* a tree structure��� or not, it could just calculate children as demanded (for example is browsing a file system), etc.

Esteban


On 23 Apr 2016, at 11:10, stepharo <stepharo@free.fr> wrote:

Ok I see.
Indeed. You are right.
If you want to help proposing one then we can improve the situation together.

Hi Stef,
I mean, Tree structure is a standard Data Structure including store, edit and visit. (endorder,preorder).
tree as a struture has a set of protocol for operations. 
TreeStruture is a class of Dolphin ( it has become an opensource project now ).
TreeStructure implements the <treeModel> protocol and organises a collection of objects into a tree like data structure.
You can organise the objects with TreeStructure  when need a tree.  Only one class for all applications. I think.

But in Pharo , there is no such a standard tree structure. so people makes theri owns. 
e.g.
FTDataSource subclass: #FTTreeDataSource
MorphTreeModel subclass: #SpecTreeModel
Model subclass: #MorphTreeModel
Dictionary subclass: #KeyedTree  (not real tree)

these implements mix tree structure and other attributes. 
if we have a standard tree struture, so we can seperate them, make the system become clean and simple.

Best Regards!

Liang