[Rcpp-devel] Create an instance of a reference class for a C++ class exported as a module from within C++?
Sorry for the long subject line but I hope it describes what I want to
do. I have a C++ class, dgTMatrix, that is exported in a module
definition.
RCPP_MODULE(RcppSp) {
...
class_("dgCMatrix")
...
;
}
Many of the methods for this class return other members of this class.
Can I create a new instance of the reference class in R from within
the module? I'm sure it is possible, I'm just wondering if there is
an easy way to do this without duplicating large chunks of the code in
Rcpp/src/Module.cpp. Can i somehow clone the SEXP representing the
current instance then swap the external pointer to the C++ object?
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Re: [Rcpp-devel] Create an instance of a reference class for a C++ class exported as a module from within C++?
This is something we have to add at some point.
At the moment the only way i see is to make an R call to "new" and construct
the object this way...
Le 2 juin 2011 à 21:31, Douglas Bates a écrit :
> Sorry for the long subject line but I hope it describes what I want to
> do. I have a C++ class, dgTMatrix, that is exported in a module
> definition.
>
> RCPP_MODULE(RcppSp) {
> ...
>class_("dgCMatrix")
>...
>;
> }
>
> Many of the methods for this class return other members of this class.
> Can I create a new instance of the reference class in R from within
> the module? I'm sure it is possible, I'm just wondering if there is
> an easy way to do this without duplicating large chunks of the code in
> Rcpp/src/Module.cpp. Can i somehow clone the SEXP representing the
> current instance then swap the external pointer to the C++ object?
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Re: [Rcpp-devel] Create an instance of a reference class for a C++ class exported as a module from within C++?
> At the moment the only way i see is to make an R call to "new" and construct
> the object this way...
>> Many of the methods for this class return other members of this class.
>> Can I create a new instance of the reference class in R from within
>> the module? I'm sure it is possible, I'm just wondering if there is
>> an easy way to do this without duplicating large chunks of the code in
>> Rcpp/src/Module.cpp. Can i somehow clone the SEXP representing the
>> current instance then swap the external pointer to the C++ object?
To elaborate a bit:
Am I off-base in thinking you can make a custom constructor for your
class that calls R's new(), being careful to avoid circularity, that
returns a blank instance to your method to be filled? Is something
like the following anywhere near this?
class MyClass {
public:
Bar(bool x_) : {} // for spawn
Bar() : {}
private:
Bar spawn() {
Environment meth("package:methods");
Function Rnew = meth["new"];
Rcpp::XPtr NewObj( Rnew(false) );
}
};
-Christian
--
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Re: [Rcpp-devel] Create an instance of a reference class for a C++ class exported as a module from within C++?
> At the moment the only way i see is to make an R call to "new" and construct
> the object this way...
>> Many of the methods for this class return other members of this class.
>> Can I create a new instance of the reference class in R from within
>> the module? I'm sure it is possible, I'm just wondering if there is
>> an easy way to do this without duplicating large chunks of the code in
>> Rcpp/src/Module.cpp. Can i somehow clone the SEXP representing the
>> current instance then swap the external pointer to the C++ object?
I played with this a little more, and the following works fine.
Nothing striking here. The part I don't understand is, can you employ
the SEXP returned by spawn() as an instance of Bar, or are you then
stuck with the R interface to Bar?
-Christian
## in R
Rcpp.package.skeleton('testmod', module=T)
//in testmod/src/rcpp_module.cpp
#include
using namespace Rcpp;
class Bar {
public:
Bar() {}
void set(int state_) { this->state = state_; }
int get() { return state; }
SEXP spawn() {
Environment meth("package:methods");
Function Rnew = meth["new"];
Function Rget("get");
SEXP NewObj( Rnew(Rget("Bar")) );
return NewObj;
}
private:
int state;
};
## in R
require(testmod)
bb = new(Bar); bb$set(3)
cc = bb$spawn(); cc$set(4)
bb$get(); cc$get()
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Re: [Rcpp-devel] Create an instance of a reference class for a C++ class exported as a module from within C++?
Le 06/06/11 06:09, Christian Gunning a écrit :
At the moment the only way i see is to make an R call to "new" and construct
the object this way...
Many of the methods for this class return other members of this class.
Can I create a new instance of the reference class in R from within
the module? I'm sure it is possible, I'm just wondering if there is
an easy way to do this without duplicating large chunks of the code in
Rcpp/src/Module.cpp. Can i somehow clone the SEXP representing the
current instance then swap the external pointer to the C++ object?
I played with this a little more, and the following works fine.
Nothing striking here. The part I don't understand is, can you employ
the SEXP returned by spawn() as an instance of Bar, or are you then
stuck with the R interface to Bar?
-Christian
## in R
Rcpp.package.skeleton('testmod', module=T)
//in testmod/src/rcpp_module.cpp
#include
using namespace Rcpp;
class Bar {
public:
Bar() {}
void set(int state_) { this->state = state_; }
int get() { return state; }
SEXP spawn() {
Environment meth("package:methods");
Function Rnew = meth["new"];
Function Rget("get");
SEXP NewObj( Rnew(Rget("Bar")) );
return NewObj;
}
private:
int state;
};
## in R
require(testmod)
bb = new(Bar); bb$set(3)
cc = bb$spawn(); cc$set(4)
bb$get(); cc$get()
I'm playing with this now. More later ...
Romain
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Romain Francois
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http://romain-francois.com
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Re: [Rcpp-devel] Create an instance of a reference class for a C++ class exported as a module from within C++?
Le 02/06/11 22:31, Douglas Bates a écrit :
Sorry for the long subject line but I hope it describes what I want to
do. I have a C++ class, dgTMatrix, that is exported in a module
definition.
RCPP_MODULE(RcppSp) {
...
class_("dgCMatrix")
...
;
}
Many of the methods for this class return other members of this class.
Can I create a new instance of the reference class in R from within
the module? I'm sure it is possible, I'm just wondering if there is
an easy way to do this without duplicating large chunks of the code in
Rcpp/src/Module.cpp. Can i somehow clone the SEXP representing the
current instance then swap the external pointer to the C++ object?
As part of the changes I've made today [see the post "returning pointers
in module methods" ], there is this function you might be interested in
(in Module.h):
namespace internal {
template
SEXP make_new_object( Class* ptr ){
Rcpp::XPtr xp( ptr, true ) ;
Function maker = Environment::Rcpp_namespace()[ "cpp_object_maker"] ;
return maker( typeid(Class).name() , xp ) ;
}
}
Maybe I should make it more public (i.e not have it in internal).
Anyway, if you give this function a pointer to an instance of a class
that has been exposed through modules, it will create the associated R
ref class object.
Romain
--
Romain Francois
Professional R Enthusiast
+33(0) 6 28 91 30 30
http://romainfrancois.blog.free.fr
http://romain-francois.com
|- http://bit.ly/kaSV6U : Stand up set at Up The Creek
|- http://bit.ly/hdKhCy : Rcpp article in JSS
`- http://bit.ly/elZJRJ : Montpellier Comedie Club - Avril 2011
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