Special-ness of root set: Impl. vs. data model

[Mark Miller]

I can see this discussion is going to lead nowhere other then a long
email debate which I haven't the time to pursue. I'll take these
actions...

1) I'll audit the API for places where I think this could be a problem
and then propose what I think should be the behavior.

2) Based on 1, I'll add tests to iMesh_unitTest.cc to test
implementation's behavior regarding use of root set and report results
from each implementation. At the very least, I am certain we'll tease
out inconsistencies between implementations on this point.

3) Based on results from 2, I'll identify what I think the prevailing
interpretation of 'root set' is from the implementation's stand point.

4) I'll rant and rave about whatever issues I believe are not consistent
with the data model and an interpretation of the root set as 'just
another entity set'

Mark



On Tue, 2010-08-31 at 08:40 -0700, Jason Kraftcheck wrote:
> On 08/31/2010 12:20 AM, Mark Miller wrote:
> > On Mon, 2010-08-30 at 19:59, Tim Tautges wrote:
> >> On 08/27/2010 02:37 PM, Miller, Mark C. wrote:
> >>>
> >> I think this is a case where full generality of the data model
> >> conflicts with usability of the interface, where here I 
> >> define that as restricting what you can do with/on the root set.
> > 
> > I am not sure where '...full generality...' is really coming in here.
> > The data model is the data model. The root set is a) a set and b) the
> > universe set. There is nothing I am doing/suggesting to 'generalize' the
> > data model. I am merely asking that the root set, since it is a set, be
> > allowed to be used as a set in ALL instances where a set is involved and
> > where it make sense at the data model level. I am asking for an
> > interpretation of the root set in the iMesh API that is 'free' from
> > implementation details.
> > 
> 
> I think I disagree with both of you (Mark and Tim) on one important aspect
> of this:  the root set is not part of the data model.  The data model has:
> the mesh, elements, vertices, entity sets, and tags on any of those.  The
> root set is a fiction in the API to allow a) specifying either the entire
> mesh or an entity set to query functions and b) used to indicate the mesh
> when interacting with tags.  It is not, nor was it ever intended to be, a
> proper set in the sense of the data model.  It is a convenience in the API
> to avoid the need to have separate versions of many functions that act on
> the mesh rather than a subset of the mesh.
> 
> - jason
-- 
Mark C. Miller, Lawrence Livermore National Laboratory
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