[std-interval] interval(NaN)

[Gabriel Dos Reis]

George Corliss <George.Corliss at marquette.edu> writes:

| Guillaume,
| 
| Let me paraphrase to see if I understand.  What I hear you saying is that if
| we (the interval community), after due consideration, are unable to decide
| on the best way to handle a situation such as interval(double, NaN), that
| situation should be considered an erroneous program.  The way a standard
| specifies "erroneous" is "undefined."

No, that is *a* way -- not the best; many of us in the C++ community
would like to decrease the number of undefined behaviour, NOT increase it.

| I had not thought of "undefined" that way before.  I have thought of
| "undefined" as a license for the implementer to do whatever she wants,
| without even the obligation to tell me.

Yes, that is how implementors understand it, and certainly the way the
C and C++ standards spell it out.

|  I have considered "undefined" as
| weaker than "implementation-defined."

and you're right.


"undefined behaviour" usually is a sign of lack of consensus, except
that people have agreed to disagree.

-- Gaby