[Rcpp-devel] Question on 5.6 Interfacing C++ code

[Dirk Eddelbuettel]

On 20 April 2011 at 10:20, Sean Robert McGuffee wrote:
| 
| 
| 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 I¹m 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?

You don't. As I said, 'R CMD INSTALL' et all do that.

Download an existing package with source, install it.  Study its sources,
study the 'Writing R Extensions' manual.  Ask on r-devel.

Basic R questions are off-topic here.
 
| >> 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

Again, I like working from an existing, working package. As I said, there are
almost 1000 to pick from.

Please direct follow-ups that have no bearing on Rcpp to r-devel.

Dirk

| 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 it¹s 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! 
| 
| 
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-- 
Dirk Eddelbuettel | edd at debian.org | http://dirk.eddelbuettel.com