[Rcpp-devel] Resolving NativeSymbolInfos from Rcpp (revisited)

[Dirk Eddelbuettel]

On 29 July 2017 at 15:00, Iñaki Úcar wrote:
| With our simulator, simmer, we are able to generate arrivals, entities
| that execute a given set of activities. One of these activities could
| be, let's say, a delay. A user can provide this delay as a fixed
| parameter to the C++ core, but also as a function that returns a
| value, giving them a lot of flexibility to implement the simulation
| model. As a trade-off, calling an R function from C++ is slow.
| 
| Now, what if the user needs flexibility *and* speed and so decides to
| pass a cppFunction instead? This is perfectly valid and works like a
| charm. In fact, this speeds up things a lot, especially if the
| function was performing some heavy processing. *However*, it means
| that we still have C++ calling R calling C++.
| 
| This is why I say, what if I can detect that situation and completely
| get rid of that thin R layer? What if I can extract the pointer and
| call C++ directly from my C++ core? I would expect an impressive
| performance improvement.

Are you aware of what we can do with Rcpp::XPtr and what e.g. the RcppDE
package does to pass __user-supplied C++ functions__ down to the core of the
optimization to avoid touching R code?   There is also a Rcpp Gallery piece
on this: http://gallery.rcpp.org/articles/passing-cpp-function-pointers/

Dirk

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