Re: Motion 52: final "Expressions" text for vote
Vincent Lefèvre, concerning §8.2:
"Such an operation phi, with interval inputs x_1, ..., x_k carrying ..."
> 1. Is the above sentence of §8.2 an error or does the standard
> require this to be still true for NaI? In any flavor?
The paragraph says "interval inputs", so NaI is not covered by it.
> 3. In the set-based flavor, according to the propagation order,
> if there's a NaI in input (thus will decoration ill), then
> the result shall have the decoration ill. Does the standard
> require that such an interval be Empty?
The rule is *not* universal. Programmers do need an escape, and
the case() operation is one of them.
I also dispute the statement that "the interval part of NaI is Empty".
In my opinion NaI does not *have* an interval part, and I would be
perfectly happy if, in contexts where *something* of type bare_interval
needs to be extracted, it could be either Entire or Empty, depending on
context.
Case in point: the set operations Intersection and ConvexHull are
defined for bare intervals only, but if an environment supports mixing
of input types, I would expect an input of NaI to return Empty for one
and Entire for the other.
Michel.
---Sent: 2013-11-22 15:47:22 UTC