Dear all,
It seems I can reference lazy-loaded data from an unloaded, unattached package
from R, but not using the equivalent Rcpp as described in the quickref
document. I checked out:
http://dirk.eddelbuettel.com/code/rcpp/html/Environment_8h_source.html and even
the scant references to environments in the C API section of "Writing R
Extensions" and doesn't see what I'm missing. I suspect this is a limitation of
R's C interface, not necessarily Rcpp itself.
I use the package nycflights13 as an example. Running `sessionInfo()` shows the
package nycflights13 is not loaded, then I run:
R --vanilla
> a <- nycflights13::flights
Which completes without error. In Rcpp, I cannot even get a handle on the
package namespace if it is not loaded.
Rcpp::cppFunction('Rcpp::Environment getUnloaded() { Rcpp::Environment
env("package:nycflights13"); return env;}')
getUnloaded()
Error in getUnloaded() :
Cannot convert object to an environment: [type=character; target=ENVSXP].
library(nycflights13)
Rcpp::cppFunction('Rcpp::Environment getUnloaded() { Rcpp::Environment
env("package:nycflights13"); return env;}')
getUnloaded()
<environment: package:nycflights13>
attr(,"name")
[1] "package:nycflights13"
attr(,"path")
[1]
"/Library/Frameworks/R.framework/Versions/3.4/Resources/library/nycflights13"
>
I also found that simple using `loadNamespace` was insufficient for the Rcpp
approach to work, but after `library` or `attachNamespace` the above function
does work.
Am I treading in another rare code path? All I want to do is use a lazy-loaded
data set in an Rcpp function when the package may not be loaded when called.
Should I just be passing it as a parameter to the function? This seems ugly.
Using Rcpp 0.12.16, R 3.4.3 on Mac.
Any advice appreciated. Thanks,
Jack
_______________________________________________
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
