Thanks so much for your wonderful work, Luke! I didn't expect such a clarification to happen this soon. This is really great.
For convenience, I created a quick web page to search the result of tools:::funAPI(). https://yutannihilation.github.io/R-fun-API/ Hope this helps those who are too lazy to install R-devel to check. Best, Yutani 2024年6月6日(木) 23:47 luke-tierney--- via R-devel <r-devel@r-project.org>: > This is an update on some current work on the C API for use in R > extensions. > > The internal R implementation makes use of tens of thousands of C > entry points. On Linux and Windows, which support visibility > restrictions, most of these are visible only within the R executble or > shared library. About 1500 are not hidden and are visible to > dynamically loaded shared libraries, such as ones in packages, and to > embedding applications. > > There are two main reasons for limiting access to entry points in a > software framework: > > - Some entry points are very easy to use in ways that corrupt internal > data, leading to segfaults or, worse, incorrect computations without > segfaults. > > - Some entry point expose internal structure and other implementation > details, which makes it hard to make improvements without breaking > client code that has come to depend on these details. > > The API of C entry points that can be used in R extensions, both for > packages and embedding, has evolved organically over many years. The > definition for the current release expressed in the Writing R > Extensions manual (WRE) is roughly: > > An entry point can be used if (1) it is declared in a header file > in R.home("include"), and (2) if it is documented for use in WRE. > > Ideally, (1) would be necessary and sufficient, but for a variety of > reasons that isn't achievable, at least not in the near term. (2) can > be challenging to determine; in particular, it is not amenable to a > computational answer. > > An experimental effort is underway to add annotations to the WRE > Texinfo source to allow (2) to be answered unambiguously. The > annotations so far mostly reflect my reading or WRE and may be revised > as they are reviewed by others. The annotated document can be used for > programmatically identifying what is currently considered part of the C > API. The result so far is an experimental function tools:::funAPI(): > > > head(tools:::funAPI()) > name loc apitype > 1 Rf_AdobeSymbol2utf8 R_ext/GraphicsDevice.h eapi > 2 alloc3DArray WRE api > 3 allocArray WRE api > 4 allocLang WRE api > 5 allocList WRE api > 6 allocMatrix WRE api > > The 'apitype' field has three possible levels > > | api | stable (ideally) API | > | eapi | experimental API | > | emb | embedding API | > > Entry points in the embedded API would typically only be used in > applications embedding R or providing new front ends, but might be > reasonable to use in packages that support embedding. > > The 'loc' field indicates how the entry point is identified as part of > an API: explicit mention in WRE, or declaration in a header file > identified as fully part of an API. > > [tools:::funAPI() may not be completely accurate as it relies on > regular expressions for examining header files considered part of the > API rather than proper parsing. But it seems to be pretty close to > what can be achieved with proper parsing. Proper parsing would add > dependencies on additional tools, which I would like to avoid for > now. One dependency already present is that a C compiler has to be on > the search path and cc -E has to run the C pre-processor.] > > Two additional experimental functions are available for analyzing > package compliance: tools:::checkPkgAPI and tools:::checkAllPkgsAPI. > These examine installed packages. > > [These may produce some false positives on macOS; they may or may not > work on Windows at this point.] > > Using these tools initially showed around 200 non-API entry points > used across packages on CRAN and BIOC. Ideally this number should be > reduced to zero. This will require a combination of additions to the > API and changes in packages. > > Some entry points can safely be added to the API. Around 40 have > already been added to WRE with API annotations; another 40 or so can > probably be added after review. > > The remainder mostly fall into two groups: > > - Entry points that should never be used in packages, such as > SET_OBJECT or SETLENGTH (or any non-API SETXYZ functions for that > matter) that can create inconsistent or corrupt internal state. > > - Entry points that depend on the existence of internal structure that > might be subject to change, such as the existence of promise objects > or internal structure of environments. > > Many, if not most, of these seem to be used in idioms that can either > be accomplished with existing higher-level functions already in the > API, or by new higher level functions that can be created and > added. Working through these will take some time and coordination > between R-core and maintainers of affected packages. > > Once things have gelled a bit more I hope to turn this into a blog > post that will include some examples of moving non-API entry point > uses into compliance. > > Best, > > luke > > -- > 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 > [[alternative HTML version deleted]] ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
