[Rcpp-devel] R.e. Debugging Rcpp packages with GDB
On Tue, Jan 18, 2011 at 6:19 PM, Dirk Eddelbuettel <edd at debian.org> wrote:
On 18 January 2011 at 15:52, Christian Gunning wrote: | On Tue, Jan 18, 2011 at 2:46 PM, | <rcpp-devel-request at lists.r-forge.r-project.org> wrote: | > | > Can people share any tricks they use to debug Rcpp packages? For example, can I "print" variables in a format that's a bit more high-level, like something that I would get if I sent them to "cout"? | > | | It's not very sophisticated, but I find that much of the time adding | Rf_PrintValue(xx) calls to code gives me as much info as I need. ?If | it's a non-SEXP object like int, then Rf_PrintValue(wrap(my_int)). | | > If that's not entirely obvious from my question, I am not a GDB expert. :-) Basically, my workflow is: "attach to the R process", "set a breakpoint at the function entry point", "single-step and print variable values". I have used watches and conditional breakpoints in GUI debuggers, but not (yet) in gdb. Are there any Rcpp-specific gotchas to using those features with GDB? | | I have 2 related "simple questions" after reading through Chapters 1 | and 4 of "Writing R Extensions": | | My build/test chain is: | | R CMD INSTALL mypackage | R --vanilla --debugger gdb | run | require(mypackage) | <test in R> | quit() | <edit code> | R CMD INSTALL mypackage | run | require(mypackage) ## reload package with edits | <lather, rinse, repeat> | | 1) ?Is there a "best" way to reload the shared library after | rebuilding it? dyn.unload() and dyn.load()? I am partial to littler. Eg sometimes I just do ?$ R CMD INSTALL foo && r -lfoo -e'someExpressionIWantToTest()' Because the 'r' (littler) starts fresh sessions I do not need to worry about unload. ? In other cases I use inline -- it depends. | 2) Is there a simple way to include debugging symbols/keep values from | getting optimized out when building with Rcpp? You could always include -g and then strip what you don't need -- which is what Debian and Ubuntu do to give you the *-dbg packages. R sits on top of Makefile logic, and make is pretty powerful language. ?You can (literally) do just about anything.... ? Setting CFGLAGS / CXXFLAGS or their PKG_* variants is probably easiest.
Or create a file $HOME/.R/Makevars and define CXXFLAGS and CFLAGS in there. I have the following contents CFLAGS= -g -pipe -std=gnu99 -Wall -pedantic CFLAGS= -g -O3 -pipe -std=gnu99 -Wall -pedantic CXXFLAGS= -g -pipe -Wall -pedantic CXXFLAGS= -g -pipe -std=c++0x -Wall -pedantic CXXFLAGS= -g -O3 -pipe -Wall -pedantic CXXFLAGS= -g -O3 -pipe -std=c++0x -Wall -pedantic and comment out the trailing lines if I want to suppress the c++0x standard or the optimization when using the debugger.