[Rcpp-devel] Question on 5.6 Interfacing C++ code
Hi, thanks!
On 4/20/11 10:03 AM, "Steve Lianoglou" <mailinglist.honeypot at gmail.com> wrote: Hi, On Wed, Apr 20, 2011 at 9:49 AM, Sean Robert McGuffee <sean.mcguffee at gmail.com> wrote:
Hi, I have a quick couple of questions about some of the documentation on the web page: http://cran.r-project.org/doc/manuals/R-exts.html#Linking-GUIs-and-other-fron t_002dends-to-R under the heading: 5.6 Interfacing C++ code Question 1: If I?m at a terminal, I can type the instructions they suggest: R CMD SHLIB X.cc X_main.cc If I wanted a package to do this, how would I tell the package to do that same thing?
Just to make sure we're all on the same page, you want an R package to compile some source code into a shared library/dll from inside R? Not sure if there's a "baked in" way for that to happen, but maybe you can invoke `R CMD WHATEVER` from inside R using the `system` function: R> ?system
ok, so where in the package would I put the system call in the package to have it run when installing the package?
Would I use the same command and just include it in a file somewhere in the package? If so, which file?
Hmm ... I'm curious what you're trying to do, exactly?
I'm trying to figure out how take commands such as " R CMD SHLIB X.cc
X_main.cc" followed by "dyn.load(paste("X", .Platform$dynlib.ext, sep =
""))," which are commands I can get to work for myself as a human
interactively, and put the commands into a package to be automatically run
when installing the package. I mean, it's great if I can compile a c++ file
and then use it inside R, but I'm only doing that so I can let other people
do that via a package. As much as I read this documentation, I keep missing
the connections between the different sections. This is a section I am
loving because it works very well. Thus, I want to figure out how to take
the baby steps I'm doing and combine them into a package. Specifically, I
want to take these two commands and insert them into a package so that these
commands will compile my code and make a dynamic ".so" file where R can
access its functions when others install my package.
Question 2:
dyn.load(paste("X", .Platform$dynlib.ext, sep = ""))
Where does .Platform$dynlib.ext come from?
What does it mean?
What do it?s components .Platform and $dynlib and .ext mean?
.Platform is lust a normal list -- it is defined internally (I guess). You can access "named" elements of a list with `$`. .Platform$dynlyb (or .Platform[['dynlib']]) tells you the extension your particular system uses for shared libraries: R> .Platform $OS.type [1] "unix" $file.sep [1] "/" $dynlib.ext [1] ".so" $GUI [1] "X11" $endian [1] "little" $pkgType [1] "mac.binary.leopard" $path.sep [1] ":" $r_arch [1] "x86_64" See ?.Platform for more help.
Ah, thanks, that clarifies exactly what .Platform$dynlib.ext is, it's ".so"
on my system.
This, the dyn.load(paste("X", .Platform$dynlib.ext, sep = "")) is equivalent
to the command dyn.load("X.so) which now makes sense in that context!