[R-pkg-devel] Call internal R functions in C
murdoch@dunc@n @end|ng |rom gm@||@com
Mon Apr 26 11:30:48 CEST 2021
On 25/04/2021 10:30 p.m., Cai Li wrote:
> Thanks Duncan! I was advised not to export those functions in the
> namespace and keep them as internals. In terms of this, could you advise
> what specific changes should I make to the C code so that I can evaluate
> them in a suitable environment? I tried something like
> "PROTECT(func_R=lang2(install("Package:::R_function"), func_data))," but
> it did not work. Sorry this may be too naive and thanks again.
That line creates the expression to evaluate, it doesn't evaluate it.
You need to call eval() (the C function) on the result. Here's some
code from rgl that does something similar:
R code to initialize:
rgl.init <- function(initValue = 0, onlyNULL = FALSE, debug =
initValue, onlyNULL, environment(rgl.init), debug )
The important thing here is "environment(rgl.init)", which is the
private environment within the package.
Then in C code, save that environment:
rglNamespace = in_namespace;
and use it later:
result = eval(PROTECT(lang2(PROTECT(install("rglFonts")),
> On Sun, Apr 25, 2021 at 8:46 PM Duncan Murdoch <murdoch.duncan using gmail.com
> <mailto:murdoch.duncan using gmail.com>> wrote:
> On 25/04/2021 7:23 p.m., Cai Li wrote:
> > Hello All,
> > I'm developing a package with C code. My question may be naive: I
> > several internal R functions that need to be called by C, but I
> cannot get
> > it to work or find a solution. It can work if I export those internal
> > functions in namespace, but it fails if I just want to keep them as
> > internal functions without exporting them. I guess I need some
> flags to
> > indicate the "internal" R internal functions? Could you please
> share your
> > thoughts on how to fix this? Much appreciated in advance!
> > // set up call to R function "R_function"
> > SEXP func_R;
> > PROTECT(func_R=lang2(install("R_function"), func_data));
> It all depends on the environment where you evaluate that expression,
> just as it would if it was R code. You can't see internal package
> functions from the global environment, you need to evaluate them in the
> package namespace environment.
> Duncan Murdoch
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