It's a problem with e.g. the Matrix package, and has been with others.
Careful use of #undef is needed; see the code there.
Another problem is mixing with Windows headers, which g++ has now in its
wisdom decided to include from some C++ headers. #under ERROR is
sometimes needed, for example, as well as length, append and Free.
It's worth noting that almost all these problems have emerged with
libg++-v3 and/or mingw-runtime-2.x. So another version might be
'Other libraries like to define things which R has already
defined.'
which is intended to help explain why projects such as R cannot suddenly
jump to the tune of g++ or glibc or mingw ... as our API has customers
too.
In the case of PI, there is a standard define, M_PI, but according to
R-exts this is included in R's headers for compatibility with S (and so is
ERROR). I do wonder if we should not have a define that removes these
compatibility defines. What might be a good name: NO_S_DEFINES?
STRICT_R_HEADERS?
In the cases of length and append we ought to bite the bullet and stop
re-defining them.
On Fri, 31 Jan 2003, Zed A. Shaw wrote:
> Hi Folks,
>
> Alright, so I'm figuring out how to embed from the various docs and
> other nuggets of hidden information, and I've managed to get a nice
> little C++ framework going which is supposed to make working with R
> embedded stuff much easier. The problem is, R likes to define things
> that other libraries also like to define. For example, the libg++-v3
> library has a macro called length, and so does R. This causes ALL
> iostream uses to fail. R also defines PI, which is defined in another
> toolkit. We also use a set of debugging macros named TRACE,
> UNIMPLEMENTED, and so on, but we can work around those problems.
>
> The work around to the iostream problem is to order the includes so
> that C++ stuff comes before R stuff. This works in most cases, but
> some don't (like with PI, TRACE, and UNIMPLEMENTED).
>
> Has anyone else run into these kinds of problems mixing R with C++?
> I'm curious how you worked around it. Thanks in advance.
--
Brian D. Ripley, ripley@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