Would it be reasonable to move the non-API stuff that cannot be hidden into header files inside a "details" directory (or some other specific naming scheme)?
That's what I use when I need to separate a public API from an internal API. On Fri, Jun 7, 2024 at 7:30 AM luke-tierney--- via R-devel <r-devel@r-project.org> wrote: > > On Fri, 7 Jun 2024, Steven Dirkse wrote: > > > You don't often get email from sdir...@gams.com. Learn why this is important > > Thanks for sharing this overview of an interesting and much-needed project. > > You mention that R exports about 1500 symbols (on platforms supporting > > visibility) but this subject isn't mentioned explicitly again in your note, > > so I'm wondering how things tie together. Un-exported symbols cannot be > > part of the API - how would people use them in this case? In a perfect > > world the set of exported symbols could define the API or match it exactly, > > but I guess that isn't the case at present. So I conclude that R exports > > extra (i.e. non-API) symbols. Is part of the goal to remove these extra > > exports? > > No. We'll hide what we can, but base packages for one need access to > some entry points that should not be in the API, so those have to stay > un-hidden. > > Best, > > luke > > > > > -Steve > > > > On Thu, Jun 6, 2024 at 10:47 AM luke-tierney--- via R-devel > > <r-devel@r-project.org> wrote: > > 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: > > > > https://urldefense.com/v3/__http://www.stat.uiowa.edu__;!!IKRxdwAv5BmarQ!foNGcMBk1Ky20Cgz66006bUDTWTxmZhh2ntk8-PLXUqCy2s6xw68UOo-fy7OsIRpHBwgMtfQyBkcYZUZBvMvo18$ > > > > ______________________________________________ > > R-devel@r-project.org mailing list > > > > https://urldefense.com/v3/__https://stat.ethz.ch/mailman/listinfo/r-devel__;!!IKRxdwAv5BmarQ!foNGcMBk1Ky20Cgz66006bUDTWTxmZhh2ntk8-PLXUqCy2s6xw68UOo-fy7OsIRpHBwgMtfQyBkcYZUZnVX5taE$ > > > > > > > > > > > > -- > 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: > https://urldefense.com/v3/__http://www.stat.uiowa.edu__;!!IKRxdwAv5BmarQ!foNGcMBk1Ky20Cgz66006bUDTWTxmZhh2ntk8-PLXUqCy2s6xw68UOo-fy7OsIRpHBwgMtfQyBkcYZUZBvMvo18$ > ______________________________________________ > R-devel@r-project.org mailing list > https://urldefense.com/v3/__https://stat.ethz.ch/mailman/listinfo/r-devel__;!!IKRxdwAv5BmarQ!foNGcMBk1Ky20Cgz66006bUDTWTxmZhh2ntk8-PLXUqCy2s6xw68UOo-fy7OsIRpHBwgMtfQyBkcYZUZnVX5taE$ ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel