R - C interface: extracting an object from an environment

Question

Say that you pass an environment R object to an internal C routine through the .Call interface. Said enviromnent has (by design) a someObject object which I want to extract and manipulate from the C side. How to do it?

To simplify my question, I just want to write a C function that returns someObject. Like this:

en <- new.env()
en$someObject <- someValue
.Call("extractObject",en)
#the above should return en$someObject

Guess the C code should then look something like

SEXP extractObject(SEXP env) {
   return SOMEMACROORFUNCTION(env, "someObject");
}

Unfortunately, I was not able to find the real SOMEMACROORFUNCTION.

Answer 1

After a little bit of googling and searching, I've found the solution:

findVar(install("someObject"),env)

in the C code is basically the equivalent of get("someObject",env) in R.