From romain.francois at dbmail.com  Wed Jun 16 12:27:59 2010
From: romain.francois at dbmail.com (Romain Francois)
Date: Wed, 16 Jun 2010 12:27:59 +0200
Subject: [Rd] using C++ finalizers for external pointers
Message-ID: <4C18A72F.7010608@dbmail.com>


Hello,

In Rcpp, we use a C++ template to finalizers for external pointers:

template <typename T>
void delete_finalizer(SEXP p){
     if( TYPEOF(p) == EXTPTRSXP ){
	T* ptr = (T*) EXTPTR_PTR(p) ;
	delete ptr ;
     }
}

This works fine. Or at least it has appeared to work fine for some time.


However, when compiled with suncc, this generates warnings [1] because 
the generated function is of C++ linkage and the finalizer type is 
declared to have C linkage in Rinternals.h

extern "C" {
  	...
	typedef void (*R_CFinalizer_t)(SEXP);
	void R_RegisterFinalizer(SEXP s, SEXP fun);
	void R_RegisterCFinalizer(SEXP s, R_CFinalizer_t fun);
	void R_RegisterFinalizerEx(SEXP s, SEXP fun, Rboolean onexit);
	void R_RegisterCFinalizerEx(SEXP s, R_CFinalizer_t fun, Rboolean onexit);
	...
}

Does anyone know a workaround ?

Would using an R finalizer (with R_RegisterFinalizer) using another 
external pointer to some class be appropriate ?

Romain

[1] : http://article.gmane.org/gmane.comp.lang.r.rcpp/433

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Romain Francois
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[Rd] using C++ finalizers for external pointers
Romain Francois