Functions to pass R objects to compiled C/C++ code that has been loaded into R.
.Call(.NAME, …, PACKAGE)
.External(.NAME, …, PACKAGE)a character string giving the name of a C function,
or an object of class "NativeSymbolInfo",
"RegisteredNativeSymbol" or
"NativeSymbol" referring to such a name.
arguments to be passed to the compiled code. Up to 65 for
.Call.
if supplied, confine the search for a character string
.NAME to the DLL given by this argument (plus the
conventional extension, .so, .dll, …).
This argument follows ... and so its name cannot be abbreviated.
This is intended to add safety for packages, which can ensure by using this argument that no other package can override their external symbols, and also speeds up the search (see ‘Note’).
An R object constructed in the compiled code.
Writing code for use with these functions will need to use internal R
structures defined in Rinternals.h and/or the macros in
Rdefines.h.
The functions are used to call compiled code which makes use of internal R objects, passing the arguments to the code as a sequence of R objects. They assume C calling conventions, so can usually also be used of C++ code.
For details about how to write code to use with these functions see
the chapter on ‘System and foreign language interfaces’ in
the ‘Writing R Extensions’ manual. They differ in the way the
arguments are passed to the C code: .External allows for a
variable number of arguments.
These functions are primitive, and .NAME is always
matched to the first argument supplied (which should not be named).
For clarity, avoid using names in the arguments passed to …
that match or partially match .NAME.
Chambers, J. M. (1998)
Programming with Data. A Guide to the S Language.
Springer. (.Call.)
The ‘Writing R Extensions’ manual.