Steve Jaffe wrote:
> In Writing R Extensions it is said that R_CallMethodDef has two optional
> fields, 'type' and 'style' (where 'style' is said to distinguish
> in/out/inout arguments).
Can you point us to the particular section and line that says
this. I think it is for the R_CMethodDef structure, not the
R_CallMethodDef.
Indeed, in Rdynload.h
typedef enum {R_ARG_IN, R_ARG_OUT, R_ARG_IN_OUT, R_IRRELEVANT} R_NativeArgStyle;
/*
These are very similar to those in unix/dynload.c
but we maintain them separately to give us more freedom to do
some computations on the internal versions that are derived from
these definitions.
*/
typedef struct {
const char *name;
DL_FUNC fun;
int numArgs;
R_NativePrimitiveArgType *types;
R_NativeArgStyle *styles;
} R_CMethodDef;
> But it doesn't give the possible values for
> 'style'.
The enum above does.
The types is described in the help file for .C or .Call, i.e.
?.C
> Looking at the header Rdynload.h (version 2.9.2) it appears that
> R_CallMethodDef does not have these extra two fields.
See above.
>
> Were they removed at some point? If so, what is the best way to call a C
> function without the overhead of copying the inputs?
The .Call() interface does not copy the R objects that it passes to the
C routine which accepts SEXP type objects (and returns a SEXP object also).
D.
>
> Thanks
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