[Rd] Feature request: put NewEnvironment and R_NewhashedEnv into API
Prof Brian Ripley
ripley at stats.ox.ac.uk
Wed Nov 15 17:44:53 CET 2006
On Wed, 15 Nov 2006, Seth Falcon wrote:
> Prof Brian Ripley <ripley at stats.ox.ac.uk> writes:
>> NewEnvironment is currently exposed as Rf_NewEnvironment.
>> R_NewHashedEnv is currrently hidden, but I'll unhide it. It does not
>> need a further prefix.
> Thank you. Could someone provide a bit more detail on how to
> determine if a given function in R's C code is exposed and/or public
> or not?
> Here's my current understanding after taking a look at Brian's patch
> A function can be hidden or not, but this is independent of whether the
> function is "sanctioned" as part of R's package API. Functions that
> are not hidden can be used from package C code, but that doesn't
> answer whether they _should_ be used.
It is the intention that no entry point in the API is hidden, so any found
would be a mistake (please report). All others will potentially be, and
probably are unless they are used by a module or a standard package or
some older package known to us.
[Hiding occurs in two places, by 'attribute_hidden' in the C source and
the file src/gnuwin/Rdll.hide.]
> To determine if a function is public, look at the headers in
> R/src/include and refer to the README.
It may be better to look in the installed headers in R_HOME/include in an
installed version. I am not sure anyone aims to keep README fully up to
> Thus, NewEnvironment and R_NewHashedEnv, are both private since they are
> declared in Defn.h. At present, one could call these function in package
> code, since they are not hidden.
There's another layer: to be in the API they need to documented in R-exts.
There are many public but non-API entry points.
API: documented in R-exts and in an installed header file
public: in an installed header file
private: visible on all systems but not in any installed header file
hidden: not visible on either Windows on a modern Unix in libR.so (or
both) -- ulitmately you need to check R.dll and libR.so.
I try to avoid the 'should' word (some posters here are far too fond of
telling us what 'R should do'): I believe what we say is that using
non-API entry points is likely to lead to breakage without any warning.
Brian D. Ripley, ripley at stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595
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