I haven't been very active lately with Rcpp, but I like Nathan's advice below. Don't redefine assert(), I think that's not friendly to inexperienced people and will just generate more questions.
Dale Smith, Ph.D. | Data Scientist | nexidia | office: +1 404 495 7220 ext 4008 | fax: +1 404 495 7221| nexidia.com -----Original Message----- From: rcpp-devel-boun...@lists.r-forge.r-project.org [mailto:rcpp-devel-boun...@lists.r-forge.r-project.org] On Behalf Of Nathan Kurz Sent: Wednesday, February 18, 2015 3:19 PM To: Miratrix, Luke Cc: rcpp-devel@lists.r-forge.r-project.org Subject: Re: [Rcpp-devel] assert() for Rcpp? On Tue, Feb 17, 2015 at 4:41 PM, Miratrix, Luke <lmirat...@fas.harvard.edu> wrote: > The proposed code: > > #include <stdio.h> > > #ifdef NDEBUG > # define assert(EX) > #else > # define assert(EX) (void)((EX) || (__assert (#EX, __FILE__, > __LINE__),0)) #endif > > void __assert (const char *msg, const char *file, int line) { > char buffer [100]; > snprintf( buffer, 100, "Assert Failure: %s at %s line #%d", msg, > file, line ); > ::Rf_error( buffer ); > } Getting more people using assert-like macros seems like a great idea. Weighing in as a C programmer with limited knowledge of Rcpp, I'd suggest: 1) Don't redefine assert() or __assert(). You'll confuse people and it will somehow manage to break things. Instead, define your own macro with a different name, likely one in all caps that starts with "R_" or "RCPP_". 2) Only keep the name 'assert' in the macro if you are keeping the semantics of assert(), that is, it dies on failure if NDEBUG not defined. If it prints a warning and recovers, or defaults to off, use a different word. I personally don't like the inverted NDEBUG approach, so would suggest a different semantics and different word. 3) It's debatable if you want to allow it to be turned off or not. If it can be turned off, people will misuse it to guard against errors and be surprised when it doesn't. I often use a noisy warning that only runs when DEBUG is positively defined (DEBUG_WARN_IF) and an abort that cannot be turned off (ERROR_ABORT_IF). 4) Don't try to snprintf() to a local buffer and then return. I don't know C++ semantics for exceptions, but at least in C, combining local stack variables with stack unwinding is asking for trouble. If you are aborting, print to STDERR directly. If you are continuing, use a normal heap allocation. Nathan Kurz n...@verse.com _______________________________________________ Rcpp-devel mailing list Rcpp-devel@lists.r-forge.r-project.org https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel _______________________________________________ Rcpp-devel mailing list Rcpp-devel@lists.r-forge.r-project.org https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel
