[Rcpp-devel] R.e. Debugging Rcpp packages with GDB

[Douglas Bates]

On Mon, Jan 24, 2011 at 9:10 PM, Andrew Redd <amredd at gmail.com> wrote:
> Davor,
> A good place to start might be to mirror the behavior of the str in base R.
>  That gives quick truncated information, the kind that is helpful in
> debugging.
> -Andrew

There is an internal function in R called inspect that does some of
that.  I think Simon wrote it for a particularly difficult debugging
problem.  Unfortunately it is not exported as part of the R API and,
as far as I can see, only be called as an .Internal call from R

> foo <- 1:10
> .Internal(inspect(foo))
@20f1420 13 INTSXP g0c4 [NAM(1)] (len=10, tl=0) 1,2,3,4,5,...
> .Internal(inspect(list(a=LETTERS[1:4], b=10:12, c=pi)))
@3195728 19 VECSXP g0c3 [ATT] (len=3, tl=0)
  @3195800 16 STRSXP g0c3 [] (len=4, tl=0)
    @2804c28 09 CHARSXP g0c1 [gp=0x20] "A"
    @2804bf8 09 CHARSXP g0c1 [gp=0x20] "B"
    @20cb5b8 09 CHARSXP g0c1 [MARK,gp=0x21] "C"
    @1eff388 09 CHARSXP g0c1 [MARK,gp=0x21] "D"
  @319d518 13 INTSXP g0c2 [] (len=3, tl=0) 10,11,12
  @28048f8 14 REALSXP g0c1 [] (len=1, tl=0) 3.14159
ATTRIB:
  @28059f0 02 LISTSXP g0c0 []
    TAG: @1ec21a8 01 SYMSXP g0c0 [MARK,NAM(2),gp=0x4000] "names"
    @31956e0 16 STRSXP g0c3 [] (len=3, tl=0)
      @202e288 09 CHARSXP g0c1 [MARK,gp=0x21] "a"
      @1ff31f8 09 CHARSXP g0c1 [MARK,gp=0x21] "b"
      @1ee5528 09 CHARSXP g0c1 [MARK,gp=0x21] "c"

I'll suggest exporting the underlying function inspect.
> On Mon, Jan 24, 2011 at 7:55 PM, Dirk Eddelbuettel <edd at debian.org> wrote:
>>
>> On 24 January 2011 at 16:36, Davor Cubranic wrote:
>> | To follow up my original post, it is possible to define GDB
>> pretty-printers using Python. (See
>> http://sourceware.org/gdb/onlinedocs/gdb/Pretty-Printing.html.) Would people
>> be interested in having Rcpp-specific pretty printers?
>>
>> That would be great. I have read about this feature ever since gcb 7.0 was
>> announced but have never used. It probably would make a lot of sense here.
>>
>> Dirk
>>
>> | Davor
>> |
>> | On 2011-01-19, at 7:01 AM, Dirk Eddelbuettel wrote:
>> |
>> | >
>> | > On 19 January 2011 at 08:43, Douglas Bates wrote:
>> | > | > | 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 $HOME/.R/Makevars and define CXXFLAGS and CFLAGS in
>> | > | there.  I have the following contents
>> | > |
>> | > | CFLAGS= -g -pipe -std=gnu99 -Wall -pedantic
>> | > | CFLAGS= -g -O3 -pipe -std=gnu99 -Wall -pedantic
>> | > | CXXFLAGS= -g -pipe -Wall -pedantic
>> | > | CXXFLAGS= -g -pipe -std=c++0x -Wall -pedantic
>> | > | CXXFLAGS= -g -O3 -pipe -Wall -pedantic
>> | > | CXXFLAGS= -g -O3 -pipe -std=c++0x -Wall -pedantic
>> | > |
>> | > | and comment out the trailing lines if I want to suppress the c++0x
>> | > | standard or the optimization when using the debugger.
>> | >
>> | > Seconded.
>> | >
>> | > That is actually what I do, including the better-than-awesome ccache:
>> | >
>> | > edd at max:~$ cat .R/Makevars
>> | > # edd 03 Mar 2009
>> | >
>> | > ## for C code
>> | > CFLAGS=-g -O3 -Wall -pipe -pedantic -std=gnu99
>> | > #CFLAGS=-O3 -g0 -Wall -pipe -std=gnu99
>> | > ## for C++ code
>> | > CXXFLAGS= -g -O3 -Wall -pipe -pedantic -Wno-variadic-macros
>> | > #CXXFLAGS= -g0 -O3 -Wall -pipe -Wno-variadic-macros
>> | > #CXXFLAGS= -O3 -g0 -Wall -pipe
>> | > ## for Fortran code
>> | > #FFLAGS=-g -O3 -Wall -pipe
>> | > FFLAGS=-O3 -g0 -Wall -pipe
>> | > ## for Fortran 95 code
>> | > #FCFLAGS=-g -O3 -Wall -pipe
>> | > FCFLAGS=-O3 -g0 -Wall -pipe
>> | >
>> | > CC=ccache gcc
>> | > CXX=ccache g++
>> | > FC=ccache gfortran
>> | > F77=ccache gfortran
>> | > MAKE=make -j4
>> | > edd at max:~$
>> | >
>> | >
>> | > The -Wno-variadic-macros was once needed when Romain was a tad more
>> | > aggressive in trying new C++0x features.
>> | >
>> | > The 'make -j4' also takes care of parallel builds.
>> | >
>> | > Dirk
>> | >
>> | > --
>> | > Dirk Eddelbuettel | edd at debian.org | http://dirk.eddelbuettel.com
>> | > _______________________________________________
>> | > Rcpp-devel mailing list
>> | > Rcpp-devel at lists.r-forge.r-project.org
>> | >
>> https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel
>> |
>>
>> --
>> Dirk Eddelbuettel | edd at debian.org | http://dirk.eddelbuettel.com
>> _______________________________________________
>> Rcpp-devel mailing list
>> Rcpp-devel at lists.r-forge.r-project.org
>> https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel
>
>
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