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!
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