Whit, I see that this could be useful in similar situations where Rcpp modules excels (generating R bindings to existing C++ classes). Language preference aside, it's less clear to me what advantage this approach (or Rcpp modules) offers average users over RefClasses + Rcpp functions, where the RefClass holds state, and the Rcpp functions operate on the state using by-reference semantics.
-Christian On Tue, Nov 29, 2016 at 5:33 AM, Whit Armstrong <armstrong.w...@gmail.com> wrote: > Have a look at this project: > https://github.com/richfitz/RcppR6 > > > On Mon, Nov 28, 2016 at 11:40 PM, Christian Gunning <x...@unm.edu> wrote: > >> Dear List, >> >> The following is a general request for advice / comment on modern Rcpp >> development best-practices for package & class development. I looked over >> the Rcpp gallery, and didn't see anything obvious that answers my >> questions - perhaps this discussion could serve as a prototype for a new >> post? >> >> ## Background >> >> I've used Rcpp modules for several projects where in-place modification >> was required for performance reasons. I like the interface - it encourages >> clean code, and yields a nice mix of performance and encapsulation. >> >> In the past, the lack of serialization has been a minor annoyance. >> Honestly, it's not something I need, but I dislike having invalid objects >> in the work-space after a quit/restart. I've spent a little time thinking >> about work-arounds, which essentially boil down to moving back and forth >> from an R list object. >> >> Looking towards the future, I also looked at the recent Rcpp dev history. >> It looks like modules has had some maintenance issues - for example, the >> last edits there (i..e, PR 454) were reverted due to Windows toolchain >> issues (i.e., https://github.com/RcppCore/Rcpp/issues/463). From my >> outside perspective, it appears that the modules code is A) hard, and B) >> not a current dev priority. >> >> ## A possible alternative: RefClass >> >> I'm able to achieve similar behavior (in-place modification using named >> methods, relatively tidy code) using a combination of R RefClasses and Rcpp >> attributes. This solves the issue of serialization, and yields reasonably >> clean code. This has the added benefit of allowing easy mixing of R and C++ >> code in class methods. >> >> From a user perspective, RefClass methods are a nice place for Rcpp >> functions that modify args in-place, since RefClass implies side-effects. >> And, in terms of style, if all C++ method functions return void, and have >> const-correct arglists, then the C++ function signatures provide something >> of a interface spec. >> >> Minimal example: >> https://gist.github.com/helmingstay/17d5d9f241c4170a29d1681db0111065 >> >> >> ## Summary of observations: >> >> * RefClass + attributes achieves similar outcomes to Rcpp modules, with >> somewhat better support (serialization, documentation, future?). >> >> * Unique to Rcpp modules is the ability to auto-magically generate >> RefClass-like R bindings for existing C++ class-based code. >> >> * For "mere mortals", Rcpp modules now look less attractive for routine >> use, given available alternatives (i.e. for anything but binding >> auto-generation) >> >> >> ## Questions: >> >> A) Any obvious problems with the above observations? >> >> B) Are there any *gotchas* with using Rcpp "modify-in-place" functions >> inside RefClass methods? >> >> C) Is anyone else doing this? Any suggested improvements on the above? >> >> Thanks much, >> Christian Gunning >> -- >> A man, a plan, a cat, a ham, a yak, a yam, a hat, a canal – Panama! >> >> _______________________________________________ >> 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 >> > > -- A man, a plan, a cat, a ham, a yak, a yam, a hat, a canal – Panama!
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