On Tue, 30 Jul 2019, Wang Jiefei wrote: > Hi all, > > I'm wondering if there is any way to define a `SET_ELT` function for an > ALTREP class? I see there are ` ALTINTEGER_SET_ELT` etc. functions exported > in Rinternal.h, but there is no corresponding ALTREP APIs to define them. > The only way to set the value of an ALTREP is through a pointer, which will > require that the ALTREP data is in memory. Is it on purpose?
For now, yes. We do support a Set_elt method for ALTSTRING classes but not yet for others. I seem to recall that there are some issues with going there for others, but we'll probably take a closer look later this year. One thing to keep in mind is that the R pass-by-value semantics require that C code duplicate an object for which MAYBE_REFERENCED is true, and the assumption in existing code is that duplicate returns an object that can safely be mutated. That places a lot of limitations on what can be done. You can see some notes on the issues in the README.md and the vignette in https://github.com/ALTREP-examples/Rpkg-mutable. Best, luke > Will there be > any plan to develop these ALTREP set element APIs? > > Best, > Jiefei > > [[alternative HTML version deleted]] > > ______________________________________________ > R-devel@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel > -- Luke Tierney Ralph E. Wareham Professor of Mathematical Sciences University of Iowa Phone: 319-335-3386 Department of Statistics and Fax: 319-335-3017 Actuarial Science 241 Schaeffer Hall email: luke-tier...@uiowa.edu Iowa City, IA 52242 WWW: http://www.stat.uiowa.edu ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
