Re: Iterative Model

Hmmm...

Will talk to Suroor about this.
Once he's done with his part, I'll re-evaluate the solution and
try to come up with a flexible design we can implement.
Either a concrete Model, or maybe a component.
Will see what works best.

--KD

>>> [email protected] 2003/12/19 15:45:26 >>>
Great!  Any chance your new found solution can be made into a general 
purpose solution that anyone can use for dealing with nested structures of 
arbitrary depth?  The solution + an example would be a great contribution 
to Barracuda!

Jake

At 10:28 AM 12/19/2003 +0200, you wrote:
>Thanks for all the help guys.
>Finally, got a solution that works.
>Diez, your suggestion about "flattening the tree" was the key to success.
>Thanks
>Suroor.
>
> >>> [email protected] 12/18/2003 12:06:52 PM >>>
>Hi guys.
>
>Havent worked on this for quite some time now.
>
>Diez, I get what you're saying below, but it still doesnt solve my problem.
>These grids get loaded into memory at application startup and if you look 
>at the following XML examples, you'll notice that there can be any 
>variation as far as depth is concerned.
>So, when processing these objects, the question of depth cannot be 
>answered except at runtime.
>How do I go about processing this?
>
>Example 1:
>   <GridRows>
>       <GridRow ID="RowOne" Label="Row One"/>
>       <GridRow ID="RowTwo" Label="Row Two"/>
>       <GridRow ID="RowThree" Label="Row Three"/>
>       <GridRow ID="RowFour" Label="Row Four"/>
>   </GridRows>
>Example 2:
>   <GridRows>
>       <GridRow ID="RowOne" Label="Row One">
>           <GridRow ID="RowOneOne" Label="Row 1.1"/>
>           <GridRow ID="RowOneTwo" Label="Row 1.2"/>
>       </GridRow>
>       <GridRow ID="RowTwo" Label="Row Two"/>
>           <GridRow ID="RowThree" Label="Row Three">
>               <GridRow ID="RowThreeOne" Label="Row 3.1"/>
>               <GridRow ID="RowThreeTwo" Label="Row 3.2">
>                   <GridRow ID="RowThreeTwoOne" Label="Row 3.2.1"/>
>                   <GridRow ID="RowThreeTwoTwo" Label="Row 3.2.2"/>
>               </GridRow>
>           <GridRow ID="RowThreeThree" Label="Row 3.3"/>
>       </GridRow>
>       <GridRow ID="RowFour" Label="Row Four"/>
>   </GridRows>
>
>
> >>> [email protected] 12/9/2003 3:26:03 PM >>>
>Hi Suroor,
>
>this is something from the list a while ago. Does this give you an idea?
>Basically, the recursion of your example is replaced by
>
>- setting the child collection to the child model when a new top-level object
>is visited in iterate-next
>- instead of diving into it recursively, the markup directives are beeing
>called on the child model and then the childs are traversed.
>
>Of course this stuff can be nested as deep as you want - but unfortunately
>only with pre-known depth.
>
>Jacob mentions two things:
>
>1) A FAQ entry about this. I'd be willing to contribute if we had setup a 
>wiki
>or something alike - it seems to me that this is the way to go these days.
>
>2) automatic parent-child-models. Well - this _could_ be done, but only if 
>the
>tree objects implement a certain Node-style interface - which is often not
>desirable.
>
>Hope this helps,
>
>Diez
>
>----------  Weitergeleitete Nachricht  ----------
>
>Subject: Re: [Barracuda] Iterative Model
>Date: Samstag, 15. März 2003 18:07
>From: Jacob Kjome <[email protected]>
>To: [email protected] 
>
>As a follow-up to what Diez says, here is something Diez actually sent me
>quite a while ago that I think might help...
>
>ParentModel extends AbstractTemplateModel implements IterativeModel {
>
>      ParentItem current;
>
>      ParentItem getCurrent() {return current;}
>
>      /* ... all the model-stuff */
>
>
>      public void loadNext() {
>          current = calcMyNextCurrentItem();
>      }
>
>}
>
>ChildModel extends AbstractTemplateModel implements IterativeModel {
>
>      public ChildModel(ParentModel); // Save the ref to ParentModel
>
>
>
>      public void preIterate() {
>          ParentItem pi = parentModel.getCurrent();
>          childs = pi.getMyChildsAsList();
>      }
>
>}
>
>
>Hope that helps.
>
>This really does need to be in a FAQ of some sort.  Anyone want to start
>work on that?  It would also be nice to have a more automatic way for child
>models to interact with parent models more automatically.  I'm not saying I
>have something in mind.  It just seems this could be done in a more elegant
>way.
>
>
>Jake

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