On 02/11/2010 10:08 AM, Romain Francois wrote:
Hello,
I've been trying to make LinkingTo work when the package linked to has
c++ code.
I've put dumb packages to illustrate this emails here ;
http://addictedtor.free.fr/misc/linkingto
Package A defines this C++ class:
class A {
public:
A() ;
~A() ;
SEXP hello() ;
} ;
Package B has this function :
SEXP say_hello(){
A a ;
return a.hello() ;
}
headers of package A are copied into inst/include so that package B can
have.
LinkingTo: A
in its DESCRIPTION file.
Also, package B has the R function ;
g <- function(){
.Call("say_hello", PACKAGE = "B")
}
With this I can compile A and B, but then I get :
$ Rscript -e "B::g()"
Error in dyn.load(file, DLLpath = DLLpath, ...) :
unable to load shared library '/usr/local/lib/R/library/B/libs/B.so':
/usr/local/lib/R/library/B/libs/B.so: undefined symbol: _ZN1AD1Ev
Calls: :: ... tryCatch -> tryCatchList -> tryCatchOne -> <Anonymous>
If I then add a Makevars in B with this :
# find the root directory where A is installed
ADIR=$(shell $(R_HOME)/bin/Rscript -e "cat(system.file(package='A'))" )
PKG_LIBS= $(ADIR)/libs/A$(DYLIB_EXT)
Then it works:
$ Rscript -e "B::g()"
[1] "hello"
So it appears that adding the -I flag, which is what LinkingTo does is
not enough when the package "linking from" (B) actually has to link to
the "linked to" package (A).
I've been looking at
http://cran.r-project.org/doc/manuals/R-exts.html#Registering-native-routines
but it seems only applicable to c(++) functions and not classes ...
What am I missing ? Should/can linkingto be extended in a way that
accomodates c++
Romain
One other way of course would be to have some lib support, so that for
example an R library holds not only R packages but shared libraries.
So for example, if as part of package A's Makevars, I copy its A.so into
R.home( component = "lib" ) and rename it libA.so :
RLIBDIR=$(shell $(R_HOME)/bin/Rscript -e "cat(R.home(component='lib'))" )
all: $(SHLIB) install
install:
cp $(SHLIB) $(RLIBDIR)/lib$(SHLIB)
cp -f A.h ../inst/include
Then B can just have this Makevars :
PKG_LIBS=-lA
as well as the "LinkingTo: A" in the description.
Now I realize that R.home(component='lib') is not the right place where
to host libA.so, as one might not have rights, etc ... but should there
be a right place, as a per-R-library lib folder ?
Romain
--
Romain Francois
Professional R Enthusiast
+33(0) 6 28 91 30 30
http://romainfrancois.blog.free.fr
|- http://tr.im/NrTG : Rcpp 0.7.5
|- http://tr.im/MPYc : RProtoBuf: protocol buffers for R
`- http://tr.im/KfKn : Rcpp 0.7.2
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