[Rcpp-devel] linking external libraries in a package

[Dirk Eddelbuettel]

On 1 January 2014 at 17:30, baptiste auguie wrote:
| Hi list, and happy new year,

Thanks, and Happy New Year from here too!

| The command I'm using to create an executable is
| 
| g++ -DHCUBATURE -o minimal hcubature.c minimal.c -lm -I /usr/local/include -O2
|  -larmadillo -framework Accelerate
| 
| where hcubature.c and associated header files come from cubature ( http://
| ab-initio.mit.edu/wiki/index.php/Cubature ). 

Summary: No external depends. No extra headers. No extra libraries.  

(Beyond the Accelerate framework which is OS X specific. I do not know if R
would add this automatically.  If it needs manual intervention, you can
handle this with src/Makevars alone. But that is a different question.)
 
| The last piece I'm missing is how to compile such source files in a package
| with the correct flags; my understanding is that most of these flags can be
| taken care of with a suitable Makevars file. I currently have the following,
| 
| PKG_LIBS = $(shell $(R_HOME)/bin/Rscript -e "Rcpp:::LdFlags()" ) $(LAPACK_LIBS)
| $(BLAS_LIBS) $(FLIBS)
| 
| but I don't see how to link hcubature.c together with another source file. Do I
| need a complete Makefile to specify this sort of command? I have zero
| experience in these matters of compilation, I'd appreciate some guidance or
| simple examples to follow. 

Just drop it into src/ and you're done.  

There are 5000+ packages on CRAN, and a "large enough" percentage with
compiled code, and a "still large enough percentage" amonth those which
includes external packages. Just look what others are doing -- eg packages
such as RSQLite include the entire SQLite project (plain C, no external
depends).  

More complicated setups exists too where you first descend into
subdirectories of src/ and build entire libraries first. IIRC the Matrix
package does -- but you don't have to.  One of the earlier Rcpp "clients"
which I helped with a package reorginisation was phylobase, and there we did
just that: copy all the external depends into src/ and have Makevars take
care of it. Which avoids the convoluted need for library building under
different OSs and ARCHs.  As I said: drop into src/ and you're done.

R actually provides a pretty rich build system. If anything, it is a tad
underdocumented.  But lists such as this one, or expert such as Simon, can
set you straight.

Let me know if you need more help.  I could fork your repo if you're lost.

Cheers,  Dirk

-- 
Dirk Eddelbuettel | edd at debian.org | http://dirk.eddelbuettel.com