On 09/12/13 21:22, bachmeier wrote:
I will write something up as soon as I can, but it might be a while before that
happens. I will also share my code for the .Call interface. Hopefully I will get
feedback from someone more knowledgeable about D.
I'll leave DConf to the experts. I'm an economist who taught himself to program.
It's always worth remembering that while there are probably plenty of people
here who are more expert in D, you may be much rarer in having practical
experience of R and in using it effectively in combination with D.
The other thing to remember is that it's valuable to highlight diverse use-cases
for the language. Don't be shy about things like this; simply publicizing the
challenges of what you're doing is valuable in itself.
So, don't assume that DConf would not want to hear about your work :-)
Your colleague might well be right, but I'm not familiar with that issue. In the
other direction (R to C) you want to copy the data before mutating. Suppose you
have
x <- c(1,2,3)
y <- x
.Call("foo", y)
R does a lazy copy of x into y, such that y is a pointer to x until the copy is
actually needed. In this example, when you pass y from R to C, all you're
passing is a pointer to the struct (SEXP). On the C side, you can do anything
you want with that pointer, and it will modify both y and x unless you make a
copy of y.
You can create an SEXP on the C side and pass it into R, but that's a bit clumsy
so I avoid it. Whether I'm embedding R in C/C++/D or vice versa I do the
allocation in R. Moving data between R and D is nothing more than passing a
pointer around.
Ahh, OK. Good to know for future reference -- thank you!
