On 9 May 2012 at 18:19, Steve Lianoglou wrote: | Hi, | | On Wed, May 9, 2012 at 5:34 PM, Jiqiang Guo <guoj...@gmail.com> wrote: | > Dirk, Thanks. | > | > As Dirk previously points out, every element of Rcpp::List is of type SEXP. | > So I looked at | > some R's doc, we should be able to get information (attributes in R's term: | > int or real, names, dims) | > from the SEXP at least using R's C functions such as examples at | > http://cran.r-project.org/doc/manuals/R-exts.html#Attributes | > and the functions used in Dirk's example. | | Assuming I'm following along here: | | As someone who trusts my R skills much more than my C(++) ones, I feel | like I'd jimmy this scenario into one which I'd do the "heavy lifting" | of type-checking the elements of a list and dispatching them to | appropriate C++ code given their class in R, then collate the results | back in R. | | (assuming the looping in R won't kill you, speedwise). | | Know what I mean? | | For instance, I'd have some R function that takes the list and directs traffic: | | theFunction <- function(x) { | stopifnot(inherits(x, "list")) | result <- sapply(x, function(xx) { | cpp.fun.name <- paste("theFunction", class(xx), sep="_") | ## Check cpp.fun.name to make sure it's a valid function | ## you defined in your C++ code, else raise an error about | ## unsupported class | .Call(cpp.fun.name, xx, PACKAGE="yourpackage") | }, USE.NAMES=TRUE) | | And you'd have suitable functions defined in your C++ side for the | different types of things you want to support, ie: | | RcppExport SEXP theFunction_integer(SEXP xx); | RcppExport SEXP theFunction_numeric(SEXP xx); | RcppExport SEXP theFunction_character(SEXP xx); | | and so on ...
Good thinking. It's just that sometimes we may get such lists from other C++ code rather than from R, so we'd also like to emulate the R behaviour. And with the various Rf_isXXX() functions (for different values of XXX) we should be able to get there... Dirk -- R/Finance 2012 Conference on May 11 and 12, 2012 at UIC in Chicago, IL See agenda, registration details and more at http://www.RinFinance.com _______________________________________________ Rcpp-devel mailing list Rcpp-devel@lists.r-forge.r-project.org https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel
