Serguei, (Extra line breaks help readibility on text only mail readers)
On 18 April 2018 at 14:51, Serguei Sokol wrote: | Le 18/04/2018 à 12:26, Georgi Boshnakov a écrit : | > I may be missing something here but | > it doesn't seem right to introduce silent coercion of NULL to vectors, etc., | > especially if it would become imposed on everybody using Rcpp/Armadillo. | Nothing is imposed. Everyone will be free to use Nullable<T> mechanism as before. | Actually, when NULL is provided to where a vector or a matrix is expected | just an error is thrown. So we can hardly imagine that someone would have | his program broken or will be misled if such coercion is introduced. | | > Even the "convenience" of this is questionable. | Right. It's a matter of taste. But with a quick glance on SO | I have seen a discussion here | https://stackoverflow.com/questions/34718570/rcpp-pass-vector-of-length-0-null-to-cppfunction | and on this list here (and follow-ups) | http://lists.r-forge.r-project.org/pipermail/rcpp-devel/2014-February/007215.html | where some people are surprised not having such coercion and even | expressed a wish like "I would be super happy if in the future the special value | R_NilValue could be converted to an empty vector, it would make things | very easy and coherent with R's behaviour." | It's also my thought but I am ready to hear the arguments of those who | think otherwise. I am not religious about it. Adding the one line is something we might be able to do. I did a partial rev.dep tests and it showed no issues. But I would like other Rcpp Core folks to weigh in too. On 18 April 2018 at 15:09, Serguei Sokol wrote: | Le 18/04/2018 à 13:32, Dirk Eddelbuettel a écrit : | > | > On 18 April 2018 at 10:26, Georgi Boshnakov wrote: | > | I may be missing something here but | > | it doesn't seem right to introduce silent coercion of NULL to vectors, etc., | > | especially if it would become imposed on everybody using Rcpp/Armadillo. | > | Even the "convenience" of this is questionable. | > | > Agreed. I am also not yet convinced by Serguei's argument. It seems a little | > invasive for an unclear (to me) use case. | I can describe my own case which made me search for a such solution. | I have an Rcpp/Armadillo function accepting in an optional argument a vector of uvec type. | It can be called from R and I can call it from other C++ functions of the same package too. | Nullable<IntegerVector> mechanism was cumbersome but sufficient (note that there is no possible Nullable<uvec>) It needs to be as<>()/wrap() convertible to/from SEXP, yes. | when only R calls were planned. But when it comes to calls from C++ I'll have to juggle with wrap() too. | Both of Nullable<T> (as well as special code for dealing with NULL case) and wrap() | become unnecessary with a neat declaration f(..., uvec v, ...). So that | an R call with 'c()' can pass as well as C++ calls with an empty uvec without | any additional hassle for treating NULL case. Could you use XPtr ? Dirk -- http://dirk.eddelbuettel.com | @eddelbuettel | e...@debian.org _______________________________________________ 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