[Rcpp-devel] idiom for creating an informative message for an exception
romain at r-enthusiasts.com
Thu Dec 2 22:46:15 CET 2010
Le 02/12/10 22:15, Douglas Bates a écrit :
> In the lme4a package I mixed calls to Rf_error and throwing C++
> exceptions. This is causing problems and I plan to replace the calls
> to Rf_error by exceptions so that there is a consistent approach.
> Many of the calls to Rf_error take advantage of the fact the Rf_error
> implicitly calls sprintf to create the error message. Thus I have
> calls like
> if (!d_x.size() == d_nrow * d_ncol)
> ::Rf_error("%s: Dim = (%d, %d) is inconsistent with x.size() = %d",
> "ddenseMatrix::ddenseMatrix", d_nrow, d_ncol, d_x.size());
> Is there a similar idiom for creating an exception's "what" argument?
> I imagine I could add std::strings and maybe use some iostreams or
> something like that ...
Maybe you can use sprintf, e.g :
require( inline )
require( Rcpp )
fx <- cxxfunction( , '
// replace 100 by whatever is large enough
// the backslashes below are just because of R escaping
std::string message( 100, \' \' ) ;
sprintf( const_cast<char*>(message.data()), "%s %d", "bla bla", 2 ) ;
return wrap( message ) ;
', plugin = "Rcpp" )
you could for example use sprintf in the body of the constructor of your
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