Thanks Martin, that's just what I'll do.

However, isn't the entire point of a groveler to build a little C program that gathers information like this for later use?  If one were to write a general purpose way to do this, wouldn't the logical place to put that code be in cffi-groveler?  Is the main hurdle here the fact that HUGE_VAL doesn't necessarily have a representation as a Lisp interger or double-float, the only two types that cvar allows?  Even though some of these sound a bit rhetorical, these are honest questions.

Zach



On Fri, Apr 26, 2013 at 8:25 AM, Martin Simmons <martin@lispworks.com> wrote:
>>>>> On Thu, 25 Apr 2013 20:55:38 -0600, Zach  said:
>
> > (constant (+huge-val+ "HUGE_VAL") :type integer)
> >
> > then
> >
> > (with-foreign-object (huge-ptr :uint64)
> >    (setf (mem-ref huge-ptr :uint64) +huge-val+)
> >   (nlopt-set-lower-bound opts huge-ptr))
>
> I have also been thinking along these lines.  The only thing I worry about
> is whether this is strictly correct or just correct in practice.  Is there
> a guarantee that a double float is always the same size as a uint64.  It's
> true on every platform I have ever programmed for (I think), but will it
> always be true?  Back when I programmed in C more often, hard coding data
> type sizes into a program just seemed wrong so I didn't do it, so I guess I
> wouldn't know.  Perhaps I am sweating a non-issue...

That's not the only problem -- on some platforms, HUGE_VAL is not a
compile-time constant.  It looks like the only portable way to get the value
is to write a C helper function to return it.

--
Martin Simmons
LispWorks Ltd
http://www.lispworks.com/