[Rcpp-devel] correct way of making custom as and wrap functions available to other packages

Hi Kevin

Thanks for your answer. I've tried declaring them as inline but the compiler
(clang, haven't tried gcc) issues a warning saying it's going to ignore the
inline statement. I'm assuming this is because the declaration is actually a
template specialisation but I haven't found a definitive answer.
If I separate the declaration from the definition, the linker now complains
as and wrap are missing. Using the interface:: attribute doesn't seem to
help either.

Best

Simon


Le 17/07/2015 16:56, Kevin Thornton a ?crit :

A good guess is that the as/wrap definitions in wrappers.h are the culprit
(https://github.com/dahtah/imager/blob/master/inst/include/wrappers.h).  Try
declaring them as inline, or separating the definition from the declaration.

?Kevin

On Jul 17, 2015, at 7:32 AM, Simon Barthelm? <simon.barthelme at gipsa-lab.fr>
wrote:

Dear list,

For a package I'm developing (https://github.com/dahtah/imager/) I had to
write custom "as" and "wrap" functions for third-party classes. I'd like to
make these wrappers accessible to other developers via inline C++ as well as
LinkingTo directives (so that they can be used in other packages).
So far I've only managed the former: I have a header file in inst/include,
called "wrappers.h", that contains the full implementations of my custom as
and wrap functions. I've written a custom inline plugin and everything works
fine. However, LinkingTo doesn't work: wrappers.h gets included in multiple
object files and I get linking errors (the linker complains about multiple
declarations of "as" and "wrap").
I understand RcppArmadillo manages to get around the problem but I can't
figure out how. What's the correct way of doing this? Is there a way of
making as and wrap inline functions so that it's safe to have header-only
implementations?

Thanks!

Simon Barthelme