Compiling R projects with multiple external libraries

Hi,

I have just learned how to use compile and link libraries using
"make" and how to create R projects using R CMD build or INSTALL.  My
understanding of both is somewhat limited and hence the question.

I have a main library written in c which depends on other external
libraries. Main library is to be called from R using .Call. The goal
is to create a single R project that will compile all the external
libraries, the main library, R-C wrappers and install it. I am unsure
about the proper structure of R project directories and the general
workflow such that: (a) external libraries and the main libraries are
built first using "make" that I already have (b) R-C Wrapper is
compiled and installed using R CMD install.

I understand that there are issues using Makefiles and that there
are preferred ways of doing these things. I am not sure how to use
Makevars instead of Makefile for this purpose. Any help and in
particular pointers to examples of R packages with multiple external
libraries would be appreciated.

If you want to create and then link to a library, say using code in a
subdirectory, use something like

.PHONY: all mylibs

all: $(SHLIB) $(SHLIB): mylibs

mylibs: (cd subdir; make)