[Rd] Experimental R_has_slot() utility

[Laurent Gautier]

2008/3/16, Martin Maechler <maechler at stat.math.ethz.ch>:
> >>>>> "LG" == Laurent Gautier <lgautier at gmail.com>
>  >>>>>     on Sat, 15 Mar 2008 16:24:26 +0800 writes:
>
>     LG> Dear list, The utility "R_has_slot" mentioned in the
>     LG> file NEWS ("Experimental R_has_slot() utility
>     LG> supplementing R_do_slot()") appears to be missing from a
>     LG> fresh checkout of the development branch.
>
>     LG> $ svn up At revision 44759.  $ grep -i has_slot `find
>     LG> include -name '*.h'` $ grep -i _slot `find include -name
>     LG> '*.h'` include/Rdefines.h:#define GET_SLOT(x, what)
>     LG> R_do_slot(x, what) include/Rdefines.h:#define
>     LG> SET_SLOT(x, what, value) R_do_slot_assign(x, what,
>     LG> value) include/Rinternals.h:SEXP R_do_slot(SEXP obj,
>     LG> SEXP name); include/Rinternals.h:SEXP
>     LG> R_do_slot_assign(SEXP obj, SEXP name, SEXP value);
>
>
>     LG> ..or did I miss it ?
>
>  Yes.  It's been so much experimental as not even making it into
>  a header ... arguably an oversight.
>  It's in src/main/attrib.c
>
>  int R_has_slot(SEXP obj, SEXP name)
>
>  It's not used anywhere currently in our own code,
>  but I had seen interesting use cases more than once.
>
>  Would you want to use it in your own code?

Yes.
My use-case is with a Python-R interface. For the low-level part
of it I am trying to use C-level functions for the common/frequent operations
 - speed concerns-. With that function I can test whether the
attribute exists, and raise an exception if it does not.

Following your comment that it could have made it to a header, I
already started using it and it is doing what I am expecting from it
(according to my limited unit-tests).

Thanks,


L.


>  Regards, Martin
>