[Rd] Detecting compilation under R

[Prof Brian Ripley]

On Thu, 14 Dec 2006, Barry Rowlingson wrote:

[Silently discarding the answer to his question, and breaching 'fair use' 
copyright provisions.]

>> So the problem is that you needed rather
>> 
>> #include <R.h>
>> #ifdef USING_R
>> x = rand_unif(0.0,1.0);
>> #else
>> #include <gsl_random.h>
>> x = gsl_runif(0.0,1.0);
>> #endif
>> 
>> since if R.h is not around, the include will not include it.

> If R.h is not around, the preprocessor will throw a tantrum:

If *no* R.h is around: easy to solve.

> cc    -c -o simple.o simple.c
> simple.c:2:15: error: R.h: No such file or directory
>
> - all of which would be solved if SHLIB and BUILD set a preprocessor flag to 
> indicate compilation by R.

What is BUILD?

> I dont see what use USING_R is. If you #include <R.h> you get it, but then 
> you know you're USING_R because you included R.h, hence USING_R is going to 
> always be defined in that code (unless the inclusion of R.h is conditional on 
> something else...).
>
> Oh but of course I've missed something... Just tell me what...

You've clipped it from my previous mail, with no indication.  As the 
posting guide points out, this is reprehensible.

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595