Re: [pooma-dev] status report

[Scott Haney]

On Friday, July 6, 2001, at 05:33 PM, Allan Stokes wrote:

> I think the only way to achieve a significant simplification here is
> to have less determination to make C++ do exactly what you want it to 
> do.

Allan,

I think we need to re-evaluate what we *really* need out of domains and, 
out of this evaluation, will come the simplification. If we decide that 
we have a requirement that necessitates the use of fancy C++, so be it. 
However, I do not believe that all of the domain complexity can be 
justified on the basis of real requirements. In particular, I know that 
domains, and a lot of the early implementation of POOMA 2.4 was an 
exploration of what is required to support extreme generality. The 
problem is that experience has shown that a lot of this generality is 
not needed and is accounting for longer compile times, worse 
performance, and code bloat. Specifically, I think it is fair to say 
that between POOMA itself and Tecolote, a reasonable number of the usage 
patterns for domains have been enumerated. It is worth cataloging these 
since this will, largely, expose the real requirements.

Consider the question of working around the non-zero-size base class 
problem. When do you need  to solve this. I believe that this is an 
issue for small value types like Vector or Tensor. The reason is that 
you may put a billion of these in an array and you'd just as soon not 
waste N billion bytes. Do we ever plan to put a billion Loc, Interval, 
or Range objects in anything? No. Therefore, *independent of whether 
compilers provide support or not*, it doesn't matter if a base class 
wastes some space. This is not a requirement and we don't have to pay 
the price of complexity to supply this feature.

Scott

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Scott W. Haney
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