On Wed, Nov 9, 2011 at 14:51, Barry Smith <bsmith at mcs.anl.gov> wrote:
> In C we could do #define PETSC_NULL ((void*) 0) and every thing > would be fine > yes > > In C++ this won't work and there is no alternative except a standard > that is 2 months old (but for those programming in C++ this is not really a > problem because there is really no need for varargs in proper C++ code). > unless they want to call our variadic functions > > Questions: > 1) Why won't it work in C++? Note that PETSC_NULL truly is suppose to > always be used as a null pointer and should never be used as 0; if int 0 is > intended then int 0 should be used. > C++ needs an explicit cast to convert from void*. So some_type *x = (void*)0; is a compilation error. It's too much to ask for an explicit cast any time PETSC_NULL is passed. > > 2) Can we at least fix it for C by using #define PETSC_NULL > ((void*) 0) in C and using 0 in C++. After all nobody really uses PETSc > from C++ :-) > This will work. They should be able to pass nullptr in C++11, NULL with GCC and some other compilers, or (void*)0 only in variadic slots (because those types aren't checked by the compiler). -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-dev/attachments/20111109/607ccbc1/attachment.html>
