[Rcpp-devel] Rostream.h header

[Alexey Stukalov]

On Sun, May 13, 2012 at 5:42 PM, Dirk Eddelbuettel <edd at debian.org> wrote:

>
> Hi Alexey,
>
> On 13 May 2012 at 16:45, Alexey Stukalov wrote:
> | thanks for the quick response, there are some clarifications below.
> |
> | I'm trying to use Rcpp::Rostream from my C++ library, not from the
> inline code,
> | so I have to deal with the headers inclusion on my own :)
>
> Oh, now I see more clearly where you come from but I don't yet understand
> where you want to go.
>
> | Basically, I want to use Rostream as a log sink for boost::log (this
> library
> | not in the mainline boost yet).
> | Because of boost-log API I have to create new Rostream object, using
> | Rcpp::Rcout is not an option.
> |
> | The minimal code that directs log to R console once the library is
> loaded looks
> | like this:
> |
> | #include <Rcpp/iostream/Rostream.h>
> | #include <boost/log/trivial.hpp>
> | #include <boost/log/sinks.hpp>
> | #include <boost/log/core.hpp>
> |
> | // Called when the library is loaded and before dlopen() returns
> | void __attribute__ ((constructor)) test_load()
> | {
> |     // initialize boost-log
> |     // Construct the R sink
> |     typedef boost::log::sinks::synchronous_sink
> | <boost::log::sinks::text_ostream_backend> text_sink;
> |     boost::shared_ptr< text_sink > pRSink = boost::make_shared<
> text_sink >
> | ();
> |
> |     // Add a stream to write log to
> |     pRSink->locked_backend()->add_stream(
> boost::make_shared<Rcpp::Rostream>
> | () );
> |
> |     // Register the sink in the logging core
> |     boost::log::core::get()->add_sink(pRSink);
> |
> |     BOOST_LOG_TRIVIAL(info) << "R test library loaded";
> | }
> |
> | // Called when the library is unloaded and before dlclose() returns
> | void __attribute__ ((destructor)) test_unload()
> | {
> | }
> |
> | To make this code work I had to add #include "Rstreambuf.h" into
> <Rostream.h>
> | for the reasons described above.
> | I hope now it's more clear.
>
> And this is code that you call from R?
>
> This is basically outside of our current scope.  Rcpp doesn't use Boost
> itself, so we can't promise that it works with boost::log etc -- this is
> essentially something you need to work out.
>
> That said, it could be made to work.  If you can suggest patches for our
> header files that will help you without affecting prior behaviour, we could
> possibly include.  Rcpp::Rostream is a good example as Jelmer added this
> without affecting anything else.
>
> Does that make sense?
>

Actually, the example above works just fine, since Rostream conforms to
ostream concept.
I just had to make the following change to Rostream.h to make it compile:

--- /usr/lib64/R/library/Rcpp/include/Rcpp/iostream/Rostream.h  2012-05-13
17:50:58.090987364 +0200
+++ /fast/opt/lib64/R/library/Rcpp/include/Rcpp/iostream/Rostream.h
2012-05-10 13:52:45.542940000 +0200
@@ -24,6 +24,8 @@

 #include <iomanip>                             // USES setw

+#include "Rstreambuf.h"
+
 // modified from
 //
http://stackoverflow.com/questions/243696/correctly-over-loading-a-stringbuf-to-replace-cout-in-a-matlab-mex-file

It would be nice if you can apply this tiny patch.

Thanks,
   Alexey


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