Le 07/07/11 15:18, Romain Francois a écrit :
Le 15/06/11 14:57, Douglas Bates a écrit :
On Wed, Jun 15, 2011 at 6:38 AM, Jonas
Rauch<[email protected]> wrote:
Hey again,
just to clarify: The final solution was to implement all methods of the
derived class that are to be exposed to R and to call the method of
the base
class explicitly:
class Bar : public Foo {
...
void doSomething() { Foo::doSomething() }
};
Yes, we've been there before. According to Romain, it would be very
tricky to expose the method of the underlying class through the
derived class but it has been done in module bindings in Python, on
which Romain patterned some of the Rcpp modules code.
It is just that I need time to steal that from Boost.Python.
This is one of the improvements I want to do in modules.
This is now on a background thread in my head so that I can have
dreams/nightmares about it. I failed a few times yesterday evening and
this morning, but I can feel I'm getting closer to at least know how to
do it.
On Wed, Jun 15, 2011 at 7:16 AM, Jonas Rauch<[email protected]>
wrote:
Actually, having just the declaration like this compiled fine but and
ended up in an unresolved symbol when loading the library.
class Bar : public Foo {
...
void doSomething();
void Action() {
[some code here]
}
};
I actually had to implement doSomething and explicitly call the
Method of
the Base class:
class Bar : public Foo {
...
void doSomething() { Foo::doSomething() }
void Action() {
[some code here]
}
};
Since I do not know the internals of Rcpp modules: how hard would it
be to
include support for derived classes?
Best regards,
Jonas
On Tue, Jun 14, 2011 at 7:36 PM, Dirk Eddelbuettel<[email protected]>
wrote:
Hi Jonas,
On 14 June 2011 at 19:06, Jonas Rauch wrote:
| I am trying to write an R interface to a library that uses derived
classes in
| the following manner:
|
| class Foo {
| ...
| virtual void Action() = 0;
| void doSomething() {
| Action();
| [do complicated stuff]
| }
| ...
| };
|
| class Bar : public Foo {
| ...
| void Action() {
| [some code here]
| }
| };
|
| class Baz : public Foo {
| ...
| void Action() {
| [some other code here]
| }
| };
|
| etc.
|
| Where the abstract class Foo defines an interface and at the same
time
provides
| base functionality that can then be applied to different
implementations of
| "Action".
|
| Is it possible to expose Bar::doSomething() to R using Rcpp
modules? I
have
| tried different things and did not get it to work.
Nice C++ design. And it should work, but I think your only choice
really
is
list all exposed functions, ie your need an explicit mention of
Bar::doSomething as well as Baz::doSomething. That way Rcpp Modules
doesn't
even know these are derived class. It just seens two identifiers to
hook
up
against. As always, I may be missing parts of the picture in which
case
Romain may come forward and correct the record....
|
| I would appreciate any help.
|
| Best regards,
| Jonas Rauch
|
|
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http://romainfrancois.blog.free.fr
http://romain-francois.com
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