Re: GNAT parameter passing, C-style?

["Robert I. Eachus" <rieachus@comcast.net>]

Keith Thompson wrote:

> For Ada, there's not much difference *to the user* between a bounded
> error and erroneous execution; they're both to be avoided.  It's an
> important distinction to implementers, though.

I know that.  I was just saying that in cases where an Ada 83 erroneous 
execution has been changed to a bounded error, I have not--and I think 
that any sane programmer would not--say "That's all right then, as long 
as the behaviour is bounded, I don't have to worry."  The same thing 
holds for implementation dependent as well.  An implementor is going to 
have to document what happens, but whether something is implementation 
dependent, a bounded error, or results in erroneous execution, the user 
sees it all the same way.  "Don't do this if you want to write 
trustworthy and portable programs."

And of course, that is the real distinction between C and Ada.  I can 
write portable C, but it is significantly harder than just programming 
in C.  In Ada I don't have to work hard to write portable code.  In 
fact, the only times I use implementation dependent code of any kind is 
when I am testing a compiler, or writing something that really is 
implementation dependent, such as an interface to a hardware register. 
Even there, only the register location (and layout) is implementation 
dependent.  The rest of the code doesn't have to be.

-- 
                                           Robert I. Eachus

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