Re: A Record Interpretation of an Array

["Marc A. Criley" <mcqada@earthlink.net>]

Mark wrote:
> 
> "Marc A. Criley" <mcqada@earthlink.net> wrote in message
> news:3B12C9E0.5E9B06C8@earthlink.net...
> 
> >
> > (In case someone asks, "What problem are you actually trying to solve
> > here?"  The answer is, to manipulate an array via a record-oriented
> > approach.  I have a lot of code that does varied and sundry things with
> > record definitions, and by considering an array as a degenerate case of
> > a record (the fields are all of the same, rather than different, types),
> > I can reuse that code to do the exact same kinds of things to arrays
> > that I already do to records.)
> 
> OK, then it seems like what you Really Want To Do :-) is to decouple your
> algorithms from data representations.  This can be done in very lightweight
> ways, and the result is something that is absolutely clear in its intent and
> does not depend upon any unchecked programming or other monkey business.
> 
> The idea is "abstract, then fulfill the abstractions" as opposed to "pretend
> it's something else that is equivalent."
> 
> How about an example?  Can you put up some code for some of the "varied and
> sundry things" that you would like to be able to reuse, and then we can see
> how that might be rewritten to be reusable?(The coercion approach seems like
> an attempt to reuse stuff that was not written to be reusable in the first
> place).

I know what you're saying here, and in 99+% of applications the
decoupling and abstraction would be done just as you describe.

What I've got here, though, is a low-level debugging aid that directly
manipulates raw byte streams, and is therefore intimately concerned with
the layout of data, whether it be scalars, records, or arrays.

In a sense, a "record" _is_ an abstraction of the byte stream (step away
for a moment from the concept of a physical Ada record--to the idea of a
record as an abstract collection of information).  I have software that
interprets the contents of the byte stream as this kind of abstract
record, which of course maps well to the bytes associated with a
physical record.  So the question then concerns the reasonableness of
mapping a physical Ada array to this same abstract record--with the
record fields representing array elements.

Marc