[R] Only referenc copy when calling C routine?

Liaw, Andy andy_liaw at merck.com
Mon Apr 12 03:43:58 CEST 2004

For me it's just a matter of getting my hands dirty, I guess.  For whatever
reason I seem to have a mental block about the PROTECT/UNPROTECT business...


> From: Duncan Murdoch [mailto:dmurdoch at pair.com] 
> On Sun, 11 Apr 2004 21:25:13 -0400, you wrote:
> >My understanding is that if DUP=FALSE, no copying is done in either
> >direction.
> >
> >If you want to avoid copying, the .Call interface is 
> probably more suitable,
> >as you pass the actual R objects to the C function.  I'm not 
> familiar with
> >that, though.
> If you're using C, .Call (or .External) is not really very hard to
> use.  You want to take a look at the examples in the Writing
> Extensions manual, and probably in one or two simple packages.
> The big limitation with .Call is that it is really only practical with
> C or C++ (because you definitely need to use the R header files),
> whereas .C and .Fortran make calls that just about any language can
> handle.
> Duncan Murdoch

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