[Rcpp-devel] reference classes in C++ :is it possible?
Hi Dirk, yes it would, 1) my_class::my_method delegates to ReferenceClass::my_method [c++ method exported] 2) ReferenceClass(R)::my_method callSuper() --> [ infinite recursion!!! ] 3) smoke + possible explosion + ... random events from HR department or some benefits: 1) my_class::my_method delegates to ReferenceClass::my_method 2) ReferenceClass(R)::my_method ( works hard to solve some problem ) 3) abstract class with R reference class impl This is still based on the assumption that one can call a ReferenceClass method... if so this may open up a door to design interfaces in c++ and implementing them in R. With some limitations: my_class::my_method()=0; would need some stub generated and linked to call R reference class. (if that possible at all) I don't not have the necessary experience to oversee all the implications of a feature/bug outlined; but find it an appealing thought to able to extend a c++ class in R where c++ runtime has the ability to call the R implementation. [c++ Interface_a] ---> [c++ Abstract_ab ] ---> Rcpp_export -> | R c_runtime | -> [ RrefClass impl_ab] [c++ Interface_b] --| [ some infrastructure to process/direct data flow ] --------------------------------> [ set of implementations to choose from ] steve
On Fri, Mar 1, 2013 at 6:35 PM, Dirk Eddelbuettel <edd at debian.org> wrote:
Hi Steven,
On 1 March 2013 at 14:34, Steven Varga wrote:
|
| Hello
|
| First thanks Dirk for the quick reply and the hint; Mr. John Chamber's
| implementation is great! gone through the documentation and followed his
| instructions. Worked well. Only one way though -- as you pointed out.
|
| I was able to get the fields from the extended class; if someone could
point
| into the direction how to get/execute methods of a Reference Class then
it may
| be doable??
Just making sure I understand: So you want to access part of a reference
class from C++? Wouldn't that violate the 'one way only view?
Dirk
|
| ..... c++ class ......
| void set_reference( SEXP xptr_){
| Rcpp::Reference ref(xptr_);
| ref.field("some_field")); // get the field data
|
| // ------- this is not implemented, any hints? --------
| ref.method("some_method")( x, y); // this would be nice to have
| }
| ...... end .......
|
| setRcppClass("World",
| module="yada",
| fields = list( some_field = "character"),
| methods = list(
| initialize = function(){
| some_field <<- "field value set"
| callSuper() # call constructor
| set_reference( .self ) # pass 'this'
| }
| ),saveAs="genWorld"
| )
|
| On Thu, Feb 28, 2013 at 8:15 AM, Dirk Eddelbuettel <edd at debian.org>
wrote:
|
| On 28 February 2013 at 04:44, Steven Varga wrote:
| | I am trying to create an abstract pattern using R reference
objects in
| C++;
| | anyone knows if this is possible/not possible? Where to look?
|
| I am not sure you can. The best (only ?) relevant documentation
might be
| John
| Chamber's example of 'Rcpp Classes' (see help(setRcppClass) in R
once Rcpp
| is
| loaded).
|
| And as I recall, he is pretty explicit that you can take a C++ class
and
| "extend" it for prototyping from the R side, but that you cannot
access
| those
| extended parts from C++ as only R sees it. I think you are hitting a
| similar
| constraint here.
|
| It would be nice if this worked but I am not quite sure that it can.
|
| Dirk
|
| --
| Dirk Eddelbuettel | edd at debian.org | http://dirk.eddelbuettel.com
|
|
|
|
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--
Dirk Eddelbuettel | edd at debian.org | http://dirk.eddelbuettel.com
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