Re: Representation clause for enumeratives

[Robert Dewar <dewar@gnat.com>]

In article <95uh36$to0$1@nnrp1.deja.com>,
  Rod Chapman <r_c_chapman@my-deja.com> wrote:

> Our usual coding standards for critical and real-time work
> advise against the use of enumerated types with rep. clauses
-
> the code gen. and runtime impact is just too gross.

I disagree with this advice, and the reason behind it. That's
MUCH too broad. There is no runtime impact if you do not use
the type for loops, arithmetic (succ/pred) or array subscripts.
If all you use it for is just assigning and comparing and
literal bit output, then this can be a valuable feature.

Yes, you could use named integers, but they would allow general
arithmetic which is likely meaningless.

For example, if you have a type representing possible opcodes
on a machine and a compiler uses them only in the context of
statements like

   generate (shr, .....)

that's perfectly reasonable, and has no deleterious runtime
impact.

It is almost ALWAYS wrong to advise that a particular feature
of the language should NEVER be used :-)



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