Re: gnat: time-slicing

[Keith Thompson <kst@cts.com>]

dewar@gnat.com (Robert Dewar) writes:
[...]
> I actually like the use of the term erroneous as opposed to
> undefined, but in any case, the point is that both the terms
> undefined in C and erroneous in Ada are technical terms. In both
> cases you will get into trouble if you think of them as meaning just
> what they mean in English.

Hmm.  It's difficult to disagree with that, but somehow I manage to do
so.  8-)}

Yes, it's important to keep in mind that technical terms mean what the
standard says they mean, which doesn't necessarily match what they
mean in plain English.  It's also important for technical terms to be
chosen so as to minimize confusion.

Nobody is likely to use the phrase "undefined behavior" in anything
other than its technical meaning, or something very close to it.  The
technical meaning happens to be very close to its plain English
meaning.  Also, it's a phrase that people aren't likely to use
accidentally.

In contrast, I've heard people refer to Ada programs as "erroneous"
when they mean simply that they're incorrect.  When we discuss Ada, we
have to consciously delete the fairly common word "erroneous" from our
vocabularies, and replace it with the technical term.  The problem is
that the meaning of the technical term diverges too far from the
common meaning.

Finally, for whatever reason, there's a tendency to use the word
"erroneous" by itself, rather than in the phrase "erroneous execution"
(which is the technical term defined in the RM).  It's common, though
incorrect, to say that a piece of code is "erroneous".  (I *think*
this is partly the fault of imprecision in the Ada 83 RM, but I don't
have a copy handy.)

-- 
Keith Thompson (The_Other_Keith) kst@cts.com  <http://www.ghoti.net/~kst>
San Diego Supercomputer Center           <*>  <http://www.sdsc.edu/~kst>
Schroedinger does Shakespeare: "To be *and* not to be"