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

Duncan Murdoch murdoch.duncan at gmail.com
Thu Apr 21 17:00:32 CEST 2011 

On 21/04/2011 10:52 AM, Sean Robert McGuffee wrote:
> Thanks,
> That's great, but I don't know how to determine what foo is. How do I
> declare the name of the package?

See the Writing R Extensions manual, or a tutorial on the topic, e.g. 
the one I gave at UseR 2008, available here:

www.r-project.org/conferences/*useR-2008*/slides/*Murdoch*.pdf
*
*It contains a few things that are no longer true (e.g. you don't need 
Perl any more), but is mostly still accurate.

Duncan Murdoch

> On 4/21/11 7:16 AM, "Duncan Murdoch"<murdoch.duncan at gmail.com>  wrote:
>
> >  On 11-04-20 11:33 AM, Sean Robert McGuffee wrote:
> >>  Hi, apparently I sent my question about using R and C++ to the wrong list,
> >>  ironically seeing as that list was called Rcpp. Anyway, I was directed to
> >>  post my question here. To summarize my current question, I have found two
> >>  commands that I want to be able to put into a package. The commands are 'R
> >>  CMD SHLIB X.cc X_main.cc' and
> >>  'dyn.load(paste("X",.Platform$dynlib.ext,sep="")),' which I would like to
> >>  run when my package is installed and maybe have the second command run again
> >>  when my package is to be used. I've been trying to figure out the
> >>  documentation and learn through examples, but I'm just not getting it and
> >>  have been trying for weeks.
> >>  Does anyone on this site have any suggestions for me?
> >
> >  Assuming those lines work on their own, just do the following:
> >
> >  1.  Put those *.cc files into the src directory of your package.  (You
> >  may need to create it.)
> >
> >  2.  Put useDynLib(foo) into the NAMESPACE file of your foo package.
> >
> >  3.  Call those functions using .C("X", args, PACKAGE="foo").
> >
> >  That's it.
> >
> >  Duncan Murdoch
> >
> >>  Thanks, Sean
> >>
> >>  |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-fro
> >>  n
> >>  |>>   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
> >>
> >>  I've tried to figure this out for weeks by looking at other packages and
> >>  reading the confusing and nonintegrated documentation, but it hasn't taught
> >>  me how to put the two commands into a package so that they are run when the
> >>  package is installed. I'm simply trying to find out where in my package I
> >>  should put the commands 'R CMD SHLIB X.cc X_main.cc' and
> >>  'dyn.load(paste("X",.Platform$dynlib.ext,sep="")),'
> >>  in order to have them run when my package is installed.
> >>
> >>
> >>  | the connections between the different sections. This is a section I am
> >>  | loving because it works very well. Thus, I want to figure out how to take
> >>  | the baby steps I'm doing and combine them into a package. Specifically, I
> >>  | want to take these two commands and insert them into a package so that
> >>  these
> >>  | commands will compile my code and make a dynamic ".so" file where R can
> >>  | access its functions when others install my package.
> >>  |
> >>  |>
> >>  |>>   Question 2:
> >>  |>>   dyn.load(paste("X", .Platform$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!
> >>  |
> >>  |
> >>  | _______________________________________________
> >>  | Rcpp-devel mailing list
> >>  | Rcpp-devel at lists.r-forge.r-project.org
> >>  | https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel
> >>
> >
>
>

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