[Rd] Define replacement functions
Hello
I tried to define replacement functions for the class mylist. When I test
them in an active R session, they work -- however, when I put them into a
package, they don't. Why and how to fix?
make_my_list - function( x, y ) {
return(structure(list(x, y, class=mylist)))
}
mylist - make_my_list(1:4, letters[3:7])
mylist
mylist[['x']] - 4:6
mylist
[[- - function(x, field, value) {
UseMethod('[[-', x)
}
[[-.mylist - function(x, field, value) {
stop( Do not assign. )
}
mylist[['x']] - 1:10
mylist
mylist$y - LETTERS[1:3]
mylist
$- - function(x, field, value) {
UseMethod('$-', x)
}
$-.mylist - function(x, field, value) {
stop( Do not assign. )
}
mylist$y - LETTERS[10:15]
Thanks for help
Sören
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Re: [Rd] Define replacement functions
No. I fixed that, the NAMESPACE file now contains:
S3method([[-, mylist)
S3method($-, mylist)
It still does not work. I also created a print method (print.mylist) which did
work out of the box, regardless of being in the NAMESPACE file or not. Could it
be somehow in here (also in my NAMESPACE file):
exportPattern(^[[:alpha:]]+)
Or could it be that the type of quoting causes the problems? Like in the
NAMESPACE I used double quotes for function definition. Do I need single quotes
or back-ticks?
Or is there a package where I can look how others implemented this kind of
functionality?
Sören
On 04.05.2015, at 16:17, Hadley Wickham h.wick...@gmail.com wrote:
Did you export the S3 methods in the NAMESPACE?
Hadley
On Mon, May 4, 2015 at 7:52 AM, soeren.vo...@posteo.ch wrote:
Hello
I tried to define replacement functions for the class mylist. When I test
them in an active R session, they work -- however, when I put them into a
package, they don't. Why and how to fix?
make_my_list - function( x, y ) {
return(structure(list(x, y, class=mylist)))
}
mylist - make_my_list(1:4, letters[3:7])
mylist
mylist[['x']] - 4:6
mylist
[[- - function(x, field, value) {
UseMethod('[[-', x)
}
[[-.mylist - function(x, field, value) {
stop( Do not assign. )
}
mylist[['x']] - 1:10
mylist
mylist$y - LETTERS[1:3]
mylist
$- - function(x, field, value) {
UseMethod('$-', x)
}
$-.mylist - function(x, field, value) {
stop( Do not assign. )
}
mylist$y - LETTERS[10:15]
Thanks for help
Sören
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[Rd] Compilation error Mac binary
Hello, the compilation of the GUTS package on CRAN for Mac produces the following error messages: http://www.r-project.org/nosvn/R.check/r-release-macosx-ix86/GUTS-00install.html I guess it is some namespace collision, but I can not reproduce it on my machine, it compiles fine here. What is the cause and which setup do I need to reproduce the errors? R: version platform i386-apple-darwin9.8.0 arch i386 os darwin9.8.0 system i386, darwin9.8.0 status major 2 minor 13.0 year 2011 month 04 day13 svn rev55427 language R version.string R version 2.13.0 (2011-04-13) I ~ $: gcc --version i686-apple-darwin10-gcc-4.2.1 (GCC) 4.2.1 (Apple Inc. build 5666) (dot 3) Copyright (C) 2007 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. I ~ $: less /opt/local/include/boost/version.hpp // Boost version.hpp configuration header file --// [...] #define BOOST_VERSION 104601 #define BOOST_LIB_VERSION 1_46_1 [...] __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
Re: [Rd] Compilation error Mac binary
Hello David On 29.06.2011, at 15:56, David Winsemius wrote: On Jun 29, 2011, at 5:33 AM, soeren.vo...@uzh.ch wrote: Hello, the compilation of the GUTS package on CRAN for Mac produces the following error messages: http://www.r-project.org/nosvn/R.check/r-release-macosx-ix86/GUTS-00install.html I guess it is some namespace collision, but I can not reproduce it on my machine, it compiles fine here. What is the cause and which setup do I need to reproduce the errors? I was going to suggest you take this up with the maintainers... but you _are_ one of the maintainers. :-) Here is the output from an attempt to compile from source, version 0.1.45, with a relatively recent version of R 2.13.0 (but not the most recent and I still use Mac OSX 10.5.8). Perhaps its brevity will be helpful, and the fact that it seems to identify different error than those flagged in the log at CRAN. Thanks for your answer. The failure on your side is clear to me: there is no installation of the boost C++ library in any of the standard include locations. I have added /opt/local/include in Makevars (Mac Ports installation of C source packages), however, I know I should but still I am reluctant to write a configure script that could circumvent non-standard installations of boost on UNIX machines. So thanks for the output, but the CRAN messages must point to something different... Regards Sören trying URL 'http://lib.stat.cmu.edu/R/CRAN/src/contrib/GUTS_0.1.45.tar.gz' Content type 'application/x-gzip' length 9842 bytes opened URL == downloaded 9842 bytes Loading required package: lattice Loading required package: sos Loading required package: brew [1] 2011-06-29 09:40:18 EDT * installing *source* package ‘GUTS’ ... ** libs *** arch - i386 g++ -arch i386 -I/Library/Frameworks/R.framework/Resources/include -I/Library/Frameworks/R.framework/Resources/include/i386 -I/opt/local/include -I/usr/local/include -I/Library/Frameworks/R.framework/Versions/2.13/Resources/library/Rcpp/include -fPIC -g -O2 -c GUTS.cpp -o GUTS.o In file included from GUTS.cpp:12: GUTS.h:21:28: error: boost/random.hpp: No such file or directory GUTS.h:22:40: error: boost/math/distributions.hpp: No such file or directory GUTS.cpp: In function ‘void to_print(double)’: GUTS.cpp:277: error: ‘cout’ was not declared in this scope GUTS.cpp: In member function ‘void GUTS::showObject()’: GUTS.cpp:281: error: ‘cout’ is not a member of ‘std’ GUTS.cpp:284: error: ‘cout’ was not declared in this scope make: *** [GUTS.o] Error 1 ERROR: compilation failed for package ‘GUTS’ * removing ‘/Library/Frameworks/R.framework/Versions/2.13/Resources/library/GUTS’ sessionInfo() R version 2.13.0 beta (2011-04-04 r55296) Platform: x86_64-apple-darwin9.8.0/x86_64 (64-bit) locale: [1] en_US.UTF-8/en_US.UTF-8/C/C/en_US.UTF-8/en_US.UTF-8 attached base packages: [1] stats graphics grDevices utils datasets methods base other attached packages: [1] mgcv_1.7-6 sos_1.3-0 brew_1.0-6 lattice_0.19-26 loaded via a namespace (and not attached): [1] grid_2.13.0Matrix_0.999375-50 nlme_3.1-101 tools_2.13.0 -- David. R: version platform i386-apple-darwin9.8.0 arch i386 os darwin9.8.0 system i386, darwin9.8.0 status major 2 minor 13.0 year 2011 month 04 day13 svn rev55427 language R version.string R version 2.13.0 (2011-04-13) I ~ $: gcc --version i686-apple-darwin10-gcc-4.2.1 (GCC) 4.2.1 (Apple Inc. build 5666) (dot 3) Copyright (C) 2007 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. I ~ $: less /opt/local/include/boost/version.hpp // Boost version.hpp configuration header file --// [...] #define BOOST_VERSION 104601 #define BOOST_LIB_VERSION 1_46_1 [...] __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel David Winsemius, MD West Hartford, CT __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
Re: [Rd] Compilation error Mac binary
Thanks Simon, Uwe and David for your helpful answers. English is not my primary language, so I was hypothesising a bit about the correct interpretation of inlining and supply inside. I thought it meant copying the headers inside the package. I was already inspecting RQuantlib but I did, so far, not get smarter. I think I will setup a VMware OS X 10.5 with an older boost. This approach seems more reliable to me than just trying around with a configure script which, eventually, I don't understand fully. Yet, interesting that GUTS builds on Win and Linux, but not on the CRAN OS X. Anyway, thanks for your help. Best Sören On 29.06.2011, at 20:05, Simon Urbanek wrote: On Jun 29, 2011, at 1:12 PM, Uwe Ligges wrote: Looks like a different boost version than the one you require. I'd suggest to talk to the Mac maintainer, Simon Urbanek (CCing). GUTS doesn't specify any system requirements, so obviously it has no business trying to use boost from the system. Also note boost is inlined in the vast majority of cases, so most packages simply supply the headers inside as to guarantee the required version is used (which I would certainly expect GUTS to do since it doesn't depend on boost according to the DESCRIPTION). Cheers, Simon On 29.06.2011 17:14, soeren.vo...@uzh.ch wrote: Hello David On 29.06.2011, at 15:56, David Winsemius wrote: On Jun 29, 2011, at 5:33 AM, soeren.vo...@uzh.ch wrote: Hello, the compilation of the GUTS package on CRAN for Mac produces the following error messages: http://www.r-project.org/nosvn/R.check/r-release-macosx-ix86/GUTS-00install.html I guess it is some namespace collision, but I can not reproduce it on my machine, it compiles fine here. What is the cause and which setup do I need to reproduce the errors? I was going to suggest you take this up with the maintainers... but you _are_ one of the maintainers. :-) Here is the output from an attempt to compile from source, version 0.1.45, with a relatively recent version of R 2.13.0 (but not the most recent and I still use Mac OSX 10.5.8). Perhaps its brevity will be helpful, and the fact that it seems to identify different error than those flagged in the log at CRAN. Thanks for your answer. The failure on your side is clear to me: there is no installation of the boost C++ library in any of the standard include locations. I have added /opt/local/include in Makevars (Mac Ports installation of C source packages), however, I know I should but still I am reluctant to write a configure script that could circumvent non-standard installations of boost on UNIX machines. So thanks for the output, but the CRAN messages must point to something different... Regards Sören trying URL 'http://lib.stat.cmu.edu/R/CRAN/src/contrib/GUTS_0.1.45.tar.gz' Content type 'application/x-gzip' length 9842 bytes opened URL == downloaded 9842 bytes Loading required package: lattice Loading required package: sos Loading required package: brew [1] 2011-06-29 09:40:18 EDT * installing *source* package ‘GUTS’ ... ** libs *** arch - i386 g++ -arch i386 -I/Library/Frameworks/R.framework/Resources/include -I/Library/Frameworks/R.framework/Resources/include/i386 -I/opt/local/include -I/usr/local/include -I/Library/Frameworks/R.framework/Versions/2.13/Resources/library/Rcpp/include -fPIC -g -O2 -c GUTS.cpp -o GUTS.o In file included from GUTS.cpp:12: GUTS.h:21:28: error: boost/random.hpp: No such file or directory GUTS.h:22:40: error: boost/math/distributions.hpp: No such file or directory GUTS.cpp: In function ‘void to_print(double)’: GUTS.cpp:277: error: ‘cout’ was not declared in this scope GUTS.cpp: In member function ‘void GUTS::showObject()’: GUTS.cpp:281: error: ‘cout’ is not a member of ‘std’ GUTS.cpp:284: error: ‘cout’ was not declared in this scope make: *** [GUTS.o] Error 1 ERROR: compilation failed for package ‘GUTS’ * removing ‘/Library/Frameworks/R.framework/Versions/2.13/Resources/library/GUTS’ sessionInfo() R version 2.13.0 beta (2011-04-04 r55296) Platform: x86_64-apple-darwin9.8.0/x86_64 (64-bit) locale: [1] en_US.UTF-8/en_US.UTF-8/C/C/en_US.UTF-8/en_US.UTF-8 attached base packages: [1] stats graphics grDevices utils datasets methods base other attached packages: [1] mgcv_1.7-6 sos_1.3-0 brew_1.0-6 lattice_0.19-26 loaded via a namespace (and not attached): [1] grid_2.13.0Matrix_0.999375-50 nlme_3.1-101 tools_2.13.0 -- David. R: version platform i386-apple-darwin9.8.0 arch i386 os darwin9.8.0 system i386, darwin9.8.0 status major 2 minor 13.0 year 2011 month 04 day13 svn rev55427 language R version.string R version 2.13.0 (2011-04-13) I ~ $: gcc --version i686-apple-darwin10-gcc-4.2.1
Re: [Rd] Compilation error Mac binary
On 29.06.2011, at 21:19, Dirk Eddelbuettel wrote: Soeren just shown resilience and persistence in getting his package written, built and now onto CRAN. The remaining step is to learn more about cross-platform build issues. Because that is the (high) standard of CRAN, and if you want to be part of it, you are expected to conform. No shortcuts. Hehehe :-D Okay, Dirk, I'll try my best :-)! Cheers Sören __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
[Rd] R CMD check on CRAN
Hello I have a package with a configure script (--include-something). How does the package pass the check on CRAN, that is, how should I signalise that check and install may need options? Thanks Sören __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
[Rd] Reference Classes, Generator Object
Hello, I am working with a reference class: Foo - setRefClass(Bar, fields = list( a = numeric), methods = list( baz = function( xa ) a - xa ) ) x - Foo$new() x$baz(2) x$a y - new(Bar) y$baz(4) y$a But that might be confusing, since new(Foo) does not work and neither does Bar$new() (which is both clear to me but -- maybe -- not to the user). So my idea was to: Bar - setRefClass(Bar, fields = list( a = numeric), methods = list( baz = function( xa ) a - xa ) ) x - Bar$new() x$baz(2) x$a y - new(Bar) y$baz(4) y$a However, this is not the way it is usually done (e.g., with Rcpp modules), why not? Thanks, Sören __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
[Rd] S4 class, passing argument names to function, modify original
Hello, an S4 class Foo is defined with a setter, $. For several reasons, the
setter calls a function, .foo.update(). However, bypassing the argument names
of the setter does not work. Question 1: Why not and how can I fix this?
Question 2: What is the way to define either the function or the setter to
modify the original object (not returning the modified copy of it an overwrite
the original by assignment)? Thanks, Sören
setClass(Foo,
representation(
N = numeric
),
prototype(
N = 1
)
)
.foo.update - function(object, ...) {
args - list(...)
for (i in slotNames(Foo)[pmatch(names(args), slotNames(Foo), nomatch=0)])
{
slot(object, i) - args[[i]]
# indeed more to do here
return(object)
}
}
setReplaceMethod($, Foo,
function(x, name, value) {
x - .foo.update(x, name=value)
x
}
)
x - new(Foo)
x
x$N - 99
x # NULL
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[Rd] Interfacing a C++ class
Hello Apologies for cross-posting, the discussion should (if) go to R-devel, but I also want to reach the rcpp-devel people. My C++ class FOO is a module available through Rcpp, and it works fine and is -- so far -- bug free. With trying to further develop my R package, I thought it was a good idea to interface my C++ workhorse FOO with an S4 class Foo. After some long and not always insightful trip through S4 classes and methods, I am not sure if I am on the right way of thinking and designing. Since there is no local assistance available, could you help to make things clearer? Just a brief outline: FOO is the C++ object, and Foo should be the S4 class. If the user creates an object, say bar, from class Foo, the creation process automatically makes a new FOO object relating to bar in that a unique name of the FOO instance is stored in a slot of bar. All the user then has to do is modify bar by simple assignments. The getters and setters ($, [) are set up and work. Each modification goes in hand with assigning new values to bar as well as updating the FOO object through available setters from FOO. So far, this way has brought me to about 100 lines, but now I read about ReferenceClasses and was wondering, if there is a much easier way of achieving my goals. Moreover, I was not sure any longer if my goals make sense or if a more advanced programmer would do it totally different (and could share some structural thinking on their approach). The idea behind my way of doing was based upon several considerations. First, a classical R object would not confuse users, as I assume users of my package to be rather non-skilled (and not willing to change that). Second, I want to create a properly programmed package for distribution on CRAN and publication, eventually. Third, I want to save objects across sessions. So if a user restores a session, a simple command, say, restore(), would do the trick to build all the related C++ objects again. However, I admit that I still have not figured out how to automatically clean up the workspace correctly before leaving a session, wanted or unwanted, that is, clean up memory before leaving home. Fourth, pure arithmetic check is done in C++, however, semantic check *should* be left to R, and the validity and class routines seem to be perfect for this. Fifth, some work should be done in R, such as the passing of data frames or samples from distributions. I hope to get some structured ideas and hints how to start and/or proceed. Thank you in advance, Sören __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
Re: [Rd] S4 class, passing argument names to function, modify original
On 04.06.2011, at 15:41, Martin Morgan wrote:
On 06/04/2011 03:07 AM, soeren.vo...@uzh.ch wrote:
Hello, an S4 class Foo is defined with a setter, $. For several reasons,
the setter calls a function, .foo.update(). However, bypassing the argument
names of the setter does not work. Question 1: Why not and how can I fix
this? Question 2: What is the way to define either the function or the
setter to modify the original object (not returning the modified copy of it
an overwrite the original by assignment)? Thanks, Sören
setClass(Foo,
representation(
N = numeric
),
prototype(
N = 1
)
)
.foo.update- function(object, ...) {
args- list(...)
for (i in slotNames(Foo)[pmatch(names(args), slotNames(Foo),
nomatch=0)]) {
slot(object, i)- args[[i]]
# indeed more to do here
return(object)
}
}
Since names(args) is 'name', and 'name' is not a slot of 'Foo', the return of
pmatch is 0 and .foo.update returns NULL. Put return(object) outside the for
loop.
setReplaceMethod($, Foo,
function(x, name, value) {
x- .foo.update(x, name=value)
x
}
)
x- new(Foo)
x
x$N- 99
x # NULL
here your intention is that name=value to be substituted with N=99, but you
end up with name=99. You could arrange to parse this correctly, but this
isn't usually what you _want_ to do and I don't really understand what you're
trying to accomplish.
Exactly, what I want to parse is N=99. To clarify, .foo.update should be the
one workhorse to do a couple of things depending on arguments on more than
one object (see my post on interfacing a C++ class, just some minutes ago).
Thus, assigning x@N = 10 (x$N, x[N]) should not only end up in x (object of
class Foo) with value 10, but also should invoke FOO$setN(10) (a setter for the
C++ object, not shown here). So far, .foo.update works perfectly and indeed
alters the object x, but the setter does not parse the argument name. I tried
with quote, substitute, deparse ..., but got none working ...
Maybe
.foo.update - function(object, name, value, ...)
{
slot(object, name) - value
## some other stuff
object
}
Hope that helps a bit.
Martin
Thanks, Sören
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Re: [Rd] Create and access several instances of a C++ class from R
On 07.05.2011, at 11:15, Romain Francois wrote: Try having do_bar with this signature: void do_bar(NumericVector data); And my advice would probably also to have your C field either as a NumericVector. NumericVector is just a thin wrapper around the internal R data structure. Having data members as direct pointers is dangerous and not a very C++ way of doing things. If you want to learn about the STL, there are many books that cover it and plenty of online resources. I use this : http://cplusplus.com/reference/stl/. Using the STL is easier than dealing with pointers and stuff. If your game is to pass down a double* to some api you use, you can use the begin method of NumericVector, this will give you the array pointer (as would REAL do on the underlying SEXP): [...] For the files: the discussion continues here: http://lists.r-forge.r-project.org/pipermail/rcpp-devel/2011-May/002261.html Regards Sören __ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
Re: [Rd] Create and access several instances of a C++ class from R
Hello
Thanks again for help!
We have attached version info, code, and contents of 00install.out at the end
of the message. The package can be found here:
http://sovo.md-hh.com/files/Foo.tar.gz
We had followed Dirks explanation in the Rcpp modules vignette and the
presentation of Rcpp modules. The steps there and the ones Dirk listed here are
basically the same, and all worked fine for us, so far. Even more, we have
adapted some of the example code to a class Foo with two methods of interest,
do_foo() and do_bar(). We have played around with various combinations of which
method to expose in the module. In the end, exposing do_foo() works, R CMD
CHECK does not complain. (Except for some namespacing error, but the same
happens when I compile the example simple, see below.)
Anyway, if we want the method do_bar() to expose, R CMD CHECK Foo stops with an
error that says: cannot convert ‘SEXPREC*’ to ‘double*’ in initialization. We
*guess* that it is pointers as arguments in methods exposed that cause errors,
because there is no wrappers as() and wrap() for pointers in Rcpp. Indee,
we know that our crystal ball may fool us.
Summarising so far, principally, Rcpp modules works for us and coding with this
module is very easy, especially with the help files provided in the package.
However, Rcpp modules does not work if you want to expose methods with pointers
as exposed methods' arguments (we assume). Yet, we have to use pointers, and
rewriting the complete class is no option.
Recently, Dirk gave us the advice to have a look at STL containers. We have
googled and found some information, and looking at it works fine, however,
working with it is somewhat beyond our C++ skills. If the STL things *are*
our *only* solution, could some reader here provide us with a specific solution
to exposing do_bar()? Or what else can we do to (1) use the class as is
(because it works with dyn.load as well as in other software outside R) and (2)
incorporate things into Rcpp modules (or other code) anyway?
Thanks for all help!
Sören and Carlo
On 07.05.2011, at 02:39, Dirk Eddelbuettel wrote:
Sören and Carlo,
On 6 May 2011 at 19:24, soeren.vo...@uzh.ch wrote:
| Hello
|
| We have a C++ class with several methods that manipulate an object. How is
| it possible to create several instances of that class *from R* in the C++
| realm, which can then be accessed via a given name character?
Yes it is, and even somewhat easily given Rcpp modules as we tried to explain
over at the Rcpp-devel list when you asked there. As a real quick
proof-of-concept, I did the following:
1) Make sure you have a recent Rcpp such as 0.9.3 or 0.9.4
2) Let Rcpp create a complete 'stub' of a working package with Rcpp modules
support for you via the Rcpp.package.skeleton.function() with the
module=TRUE argument:
R library(Rcpp)
R Rcpp.package.skeleton(simple, module=TRUE)
Creating directories ...
Creating DESCRIPTION ...
Creating NAMESPACE ...
Creating Read-and-delete-me ...
Saving functions and data ...
Making help files ...
Done.
Further steps are described in './simple/Read-and-delete-me'.
Adding Rcpp settings
added RcppModules: yada
added Depends: Rcpp
added LinkingTo: Rcpp
added useDynLib directive to NAMESPACE
added Makevars file with Rcpp settings
added Makevars.win file with Rcpp settings
added example header file using Rcpp classes
added example src file using Rcpp classes
added example R file calling the C++ example
added Rd file for rcpp_hello_world
copied the example module
R
3) As you are keen to see that we get actual new objects, I am just doing
the minimal code for by adding one for a new class member function:
void showmyaddress() const { std::cout Address is this
std::endl; }
which I add to the class 'World' in file simple/src/rcpp_module.rcpp -- on
line 32 if it matters. I also add this line to the module definition in
the same file on line 62:
.const_method( showmyaddress, World::showmyaddress, get *this ptr
address)
It doesn't matter that the method is const, you can do without const in
both eg
void showmyaddress() { std::cout Address is this std::endl; }
.method( showmyaddress, World::showmyaddress, get *this ptr address)
All that the code does is reveal its pointer to stdout.
4) Install it via
$ R CMD INSTALL simple
5) Try it in R (and I first
R library(simple)
Loading required package: Rcpp
R World
C++ class 'World' 0x2b84940
Constructors:
World()
Fields: No public fields exposed by this class
Methods:
std::string greet()
docstring : get the message
void set(std::string)
docstring : set the message
void showmyaddress() const
docstring : get *this ptr address
R
R w1 - new( World )
R w1$showmyaddress()
Address is 0x2748370
[Rd] Create and access several instances of a C++ class from R
Hello
We have a C++ class with several methods that manipulate an object. How is it
possible to create several instances of that class *from R* in the C++ realm,
which can then be accessed via a given name character? Symbolic example (we
hope this illustrates our problem):
// C++ side:
class Foo{
...
}
// perhaps:
void my_new_instance_wrapper(the_character) // plain to see that I am no C++
programmer ;-)
{
static Foo the_character; // no return needed since we know the name of the
instance = the_character
}
# R side:
create_new_instance - function(name){
dono_what_to_use_here(???, class)
}
# perhaps:
create_new_instance - function(name){
.C(my_new_instance_wrapper, as.character(name))
}
dyn.load(Foo)
obj1 - create_new_instance(bar, class=Foo)
obj2 - create_new_instance(baz, class=Foo)
str(obj1)
: character which can be manipulated using class methods in the C++ realm
What we do not want: make simple copies of the object in R; use Rcpp modules
(we tried that without success, pointers in constructors cause trouble);
re-write our code such that C++ only works off heavy code, the rest is
R-side. What we want: interfacing (from the R-side) instances of our class
where the instances exist in the C++ realm.
Either there is a function (or code) in R that solve this task, perhaps by
returning pointers to instances of C++ classes. (Or there is a possibility to
create a wrapper in C++ creating a new instance, the wrapper we do not know of.)
Thanks for any notes, tips, experiences.
Sören and Carlo
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