itaps-parallel Mesh Instances

[Carl Ollivier-Gooch]

Mark Miller wrote:
> Hi Carl,
> 
> So, 'merging' means to have both meshes managed by a single instance
> with perhaps different entity sets being used to keep them distinct? And,
> 'co-existence' is both meshes existing as separate instances but behind
> a 'multiplexor' that keeps the two instances distinct? I like this terminology.
> 
> However, and not to de-rail the discussion of what a 'mesh' is in the ITAPS
> context but I didn't see how Jason's solution permitted 'co-existance'. I
> thought with a single iMesh isntance, you could have it be an A implementation
> or a B implementation but that a single instance held by
> the application could NOT be hold both an A and a B implementation simultaneously.
> Was I wrong in that understanding? If it could, I didn't see any way for the
> application to give the API a handle to that single instances and then say it
> wants to act on the A one or the B one. Am I missing something here?

Actually (and I think I can trust Jason to correct me if I'm wrong), 
what the multiplexer does is make it possible for two -different- 
implementations but (necessarily, in the C API) the -same- function 
names to coexist.  The multiplexer basically wraps the two different 
implementations, and passes calls through to the correct implementation 
based on the mesh instance handle.

I'm sure I butchered the details there, but hopefully I got the big 
picture about right....

In any event, yes, I agree that a single instance can't be both an A 
implementation and a B implementation simultaneously, although a single 
-function- from the interface can (as I sort of described above) branch 
to calls to that same function in an A or a B implementation, depending 
on the mesh instance.  (Yes, at least an implicit registration of 
instances is required for this to work smoothly, methinks...)

Carl

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Dr. Carl Ollivier-Gooch, P.Eng.                   Voice: +1-604-822-1854
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