Re: [e4-dev] e4 Model Questions and comments

[Eric Moffatt <emoffatt@xxxxxxxxxx>]

+1 

I'd say the main difference between
a 'descriptor' and a 'part' is that the descriptor is *not* a UIElement,
it is never meant to be rendered. The function of a 'descriptor' is to
provide input for some function (i.e. 'createPart'(PartDescriptor desc))
that will modify the actual UI model. Just as a PerspectiveDescriptor is
just a weak reference to a perspectiveFactory (which, on invocation constructs
the presentation model).

Eric

From:	Hallvard Trætteberg <hal@xxxxxxxxxxx>
To:	E4 Project developer mailing list <e4-dev@xxxxxxxxxxx>
Date:	03/05/2010 06:01 PM
Subject:	Re: [e4-dev] e4 Model Questions and comments
Sent by:	e4-dev-bounces@xxxxxxxxxxx

---

Boris Bokowski wrote:
> It's understandable how we ended up in the current state, but I agree
> with Tom's comments that we don't have the right shape for this yet.
> PartDescriptor should not be derived from Part. It needs many of the
> same attributes and references, but not all.

I agree. That two classes need the same attributes/references is not a
reason for introducing inheritance. If you want reuse, you could move 
the attributes into a "mixin", i.e. a common superclass that's
not the 
primary superclass. In this case, it may work to switch the 
super/sub-relationship: let PartDescriptor inherit from Part. It all 
depends on the expectations of users of the class.

Hallvard

> 
> Any takers for changing the model to the better?
> 
> Boris
> 
> Inactive hide details for Paul Webster ---03/05/2010 08:08:19 AM---Hi
> Tom, On Thu, Mar 4, 2010 at 5:23 PM, Tom Schindl <tom.schPaul Webster
> ---03/05/2010 08:08:19 AM---Hi Tom, On Thu, Mar 4, 2010 at 5:23 PM,
Tom 
> Schindl <tom.schindl@xxxxxxxxxxxxxxx> wrote:
> 
> 
> From:                
> Paul Webster <pwebster@xxxxxxxxxxxxxxxxxxx>
> 
> To:                
> E4 Project developer mailing list <e4-dev@xxxxxxxxxxx>
> 
> Date:                
> 03/05/2010 08:08 AM
> 
> Subject:              
  
> Re: [e4-dev] e4 Model Questions and comments
> 
> Sent by:              
  
> e4-dev-bounces@xxxxxxxxxxx
> 
> ------------------------------------------------------------------------
> 
> 
> 
> Hi Tom,
> 
> On Thu, Mar 4, 2010 at 5:23 PM, Tom Schindl 
> <tom.schindl@xxxxxxxxxxxxxxx> wrote:
>  > If I get this right the descriptor is something one uses
to contribute a
>  > Part-Description to through ModelComponent and Part the
thing that
>  > should end up as part of our UI-Workbench-Model.
> 
> PartDescriptors serve one purpose -> they  are templates for
creating
> Parts.  PartDescriptor->Part is the equivalent of
> ViewDescriptor->ViewPart in the 3.x world.  PartDescriptors
are stored
> in a part of the model that's not rendered.  They need to contain
> everything necessary to generate the Part so it can be rendered (which
> is pretty well every field).
> 
> Right now we take the shortcut of simply cloning the PartDescriptor
> (which is a Part) so that it can be rendered, but that's simply our
> current implementation, not a requirement.
> 
>  >
>  > This (IMHO) incorrect extending of Part is also the problem
we are
>  > seeing in ModelComponent which has the following attributes:
>  >
>  > PartDescriptorContainer {
>  >   descriptor: List<PartDescriptor>
>  > }
>  >
>  > ModelComponent extends PartDescriptorContainer {
>  >   children: List<UIElement>
>  > }
>  >
>  > So because PartDescriptor is a Part I can also contribute
it through the
>  > children-Attribute though this probably not I wanted to
do.
> 
> Probably not, as it will be rendered :-)
> 
> ModelComponent also serves a purpose.  It's supposed to be a
loadable
> fragment of the model, that we can then apply to the real model (kind
> of an extension point for models).
> 
> Really what we are trying to do with ModelComponent is to add to the
> model instance by merging model fragments into it.  If there's
already
> a well known EMF way to do this, it would be good to know :-)  I
> recently ran into a problem where the model has commands defined,
but
> I can't use the model fragment to add a menu item because it cannot
> resolve the reference to its command ... since that's in the already
> loaded model instance.
> 
> Later,
> PW
> 
> -- 
> Paul Webster
> Hi floor.  Make me a sammich! - GIR
> _______________________________________________
> e4-dev mailing list
> e4-dev@xxxxxxxxxxx
> https://dev.eclipse.org/mailman/listinfo/e4-dev
> 
> 
> 
> ------------------------------------------------------------------------
> 
> _______________________________________________
> e4-dev mailing list
> e4-dev@xxxxxxxxxxx
> https://dev.eclipse.org/mailman/listinfo/e4-dev

_______________________________________________
e4-dev mailing list
e4-dev@xxxxxxxxxxx
https://dev.eclipse.org/mailman/listinfo/e4-dev