Re: Ada vs C++ (Expression Templates)

["James B. White, III (Trey)" <trey@osc.edu>]

Robert Dewar wrote:
> You say that you can produce wonderful interfaces with this amazing
> capability. What is interesting is to look at such an interface, and
> then ask how that interface would be reflected and implemented in
> other languages. 

I have done exactly this. I started with a small sample calculation used
as an example in an article on expression templates. I implemented the
example in Ada using many techniques. I'll be giving a talk at Tri-Ada
on the results.

> Specific examples typically show that such claims
> are simply inflated and have little substance!

This is what I hoped to prove! I *wanted* to show that these ugly
expression templates were either unnecessary or easier to implement in
Ada. Unfortunately, neither was the case. In my field, high-performance
computing, an order of two difference in performance is significant. For
Ada implementations that created the desired interface, the execution
times were more like three times those of C++ with expression templates.
And the nature of the example calculation would tend to minimizes
differences between compilers, so other examples could perform even
worse!

In other fields, the relative priority of performance versus ease of
development isn't so skewed towards performance. I, however, am in the
unfortunate situation where the performance benefits of expression
templates probably outweigh the other benefits of Ada over C++.


-- 
James B. White, III (Trey)
Ohio Supercomputer Center
trey@osc.edu
<http://www.osc.edu/~trey/>
Phone: (614)292-9291  Fax: (614)292-7168