[Rcpp-devel] question re: LdFlags, RcppLdFlags

(Combining two of your emails)

On 10 October 2013 at 01:08, Romain Francois wrote:
| RcppGSL does not export its LdFlags, if it did, you'd see the warning
| when you load it.

Good catch ... but turns out I don't (to my surprise).

It seems to work. Maybe NAMESPACE really do help.  Full log at bottom.

| Why would you import Rcpp's LdFlags inside RcppGSL's namespace, you
| don't use it there.

R CMD check did complain, I guess it must grep for src/ to find it in
Makevars. Once I imported the complaint went away.

On 10 October 2013 at 01:18, Romain Francois wrote:
| > That's pretty.  For all the Rcpp-using package, we can assume Rcpp to be
| > there so it may as well pivot over and call a plugin from 'foo'.
|
| I think it is worth looking in that direction.

We'll see if we need it. Kevin's point etc.

| > The other immediate defensive way would be to use NAMESPACE etc on the client
| > package and not load Rcpp and Rcpp$foo but just importFrom() etc what is needed.
|
| Maybe that works.

Generally speaking, and as I understand recent r-devel threads, Imports: and
importFrom(...) is how we are supposed to work with NAMESPACEs now.  That is
also what I did here, and what you roundly mocked one email ago (see above).

I am sure we'll find a way to sort it all out.

Dirk

Log below

edd at max:~/svn/rcpp/pkg$ svn di RcppGSL     ## now exporting LdFlags in RcppGSL
Index: RcppGSL/NAMESPACE
===================================================================
--- RcppGSL/NAMESPACE	(revision 4567)
+++ RcppGSL/NAMESPACE	(working copy)
@@ -3,7 +3,8 @@
  importFrom(utils,assignInNamespace)
  importFrom(Rcpp,LdFlags)
  export(fastLmPure,
-       fastLm)
+       fastLm,
+       LdFlags)
  S3method(fastLm, default)
  S3method(fastLm, formula)
  S3method(predict, fastLm)
edd at max:~/svn/rcpp/pkg$ R CMD INSTALL RcppGSL_0.2.0.3.tar.gz ## using rebuilt tar.gz
* installing to library ?/usr/local/lib/R/site-library?
* installing *source* package ?RcppGSL? ...
checking for gcc... gcc
checking for C compiler default output file name... a.out
checking whether the C compiler works... yes
checking whether we are cross compiling... no
checking for suffix of executables...
checking for suffix of object files... o
checking whether we are using the GNU C compiler... yes
checking whether gcc accepts -g... yes
checking for gcc option to accept ISO C89... none needed
checking for gsl-config... /usr/bin/gsl-config
checking for Rscript... yes
configure: creating ./config.status
config.status: creating src/Makevars
** libs
ccache g++-4.7 -I/usr/share/R/include -DNDEBUG -I/usr/include -I../inst/include  -I"/usr/local/lib/R/site-library/Rcpp/include"   -fpic  -g -O3 -Wall -pipe -Wno-unused -pedantic  -c fastLm.cpp -o fastLm.o
g++-4.7 -shared -o RcppGSL.so fastLm.o -L/usr/lib -lgsl -lgslcblas -lm -L/usr/local/lib/R/site-library/Rcpp/lib -lRcpp -Wl,-rpath,/usr/local/lib/R/site-library/Rcpp/lib -L/usr/lib/R/lib -lR
installing to /usr/local/lib/R/site-library/RcppGSL/libs
** R
** inst
** preparing package for lazy loading
** help
*** installing help indices
** building package indices
** installing vignettes
** testing if installed package can be loaded
* DONE (RcppGSL)
edd at max:~/svn/rcpp/pkg$ R

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tend to be either 'obscure' or 'fixed' :)
    -- Barry Rowlingson (in response to a request for rgdal to work around a well-known bug in ArcGIS)
       R-SIG-Geo (March 2012)

R> library(RcppGSL)          ## no warning !!
R> LdFlags                   ## local
function (print = TRUE)
{
     if (print)
         cat(.pkgglobalenv$gsl_libs)
     else .pkgglobalenv$gsl_libs
}
<environment: namespace:RcppGSL>
R> Rcpp::LdFlags             ## remote from Rcpp
function (static = staticLinking())
{
     cat(RcppLdFlags(static = static))
}
<environment: namespace:Rcpp>
R>