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 ...
Hello,
I've added the sprintf template, defined as:
template <int MAX_SIZE>
const char* sprintf( const char *format, ...) {
static char buffer[MAX_SIZE];
va_list(ap);
va_start(ap, format);
vsprintf( buffer, format, ap);
va_end(ap);
buffer[MAX_SIZE] = '\0';
return strdup( buffer ) ;
}
so that we can do things like :
fx <- cxxfunction( , '
return CharacterVector::create(
sprintf<100>( "bla %d", 10 ),
sprintf<100>( "bla %s %d", " bla" , 10)
);
', plugin = "Rcpp", verbose = TRUE
)
fx()
This way, I think you can create your exception class like this:
fy <- cxxfunction( , '
throw foo_exception( 10, 10, 10 ) ;
', includes = '
class foo_exception : public std::exception {
public:
foo_exception( int nrow_, int ncol_, int size_):
nrow(nrow_), ncol(ncol_), size(size_){}
inline const char* what() const throw(){
return sprintf<100>(
"%s: Dim = (%d, %d) is inconsistent with x.size() =
%d",
"ddenseMatrix::ddenseMatrix", nrow, ncol, size
) ;
}
~foo_exception() throw(){}
private:
int nrow, ncol, size ;
} ;
', plugin = "Rcpp", verbose = TRUE
)
> tryCatch( fy(), error = function(e) writeLines( conditionMessage(e) ) )
ddenseMatrix::ddenseMatrix: Dim = (10, 10) is inconsistent with x.size()
= 10
sprintf is a template, and static data is allocated with it. The
parameter should be bug enough to host the full message.
one thing you can do is instantiate the template once :
const char* (*my_sprintf)(const char*, ...) = &sprintf<100> ;
Romain
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Romain Francois
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http://romainfrancois.blog.free.fr
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