Hi,
I think this is a bug (even though I can't find documentation
explicitly saying that it should work). Basically, Rf_PrintValue(obj)
fails when 'obj' is an S4 object that should be printed using show()
rather than print(). From the error message I'm guessing that the need
to use show is detected correctly but then show is not found.
"cbind2" in the code below is just a representative object, the same
holds for the few other S4 objects I have tried.
The following uses r-devel on i686-pc-linux-gnu, but the results are
same with R 2.4.1 (with suitable changes to the R_ParseVector call).
On powerpc Linux I get a segfault.
$ RPROG=R-devel
$ ${RPROG} --version | head -1
R version 2.6.0 Under development (unstable) (2007-04-06 r41080)
$ export LD_LIBRARY_PATH=`${RPROG} RHOME`/lib
$ cat parseEvalS4.c
#include <Rinternals.h>
#include <Rembedded.h>
#include <R_ext/Parse.h>
int main(int argc, char *argv[])
{
SEXP e, val;
int i, errorOccurred;
ParseStatus status;
char *cmds[] = { "show(5)", "show(cbind2)",
"cbind2" };
argv[0] = "R";
Rf_initEmbeddedR(argc, argv);
for (i = 0; i < 3; i++) {
printf("** I **: Executing command: %s\n", cmds[i]);
PROTECT(e = R_ParseVector(mkString(cmds[i]), -1, &status,
R_NilValue));
val = eval(VECTOR_ELT(e, 0), R_GlobalEnv);
printf("** I **: Evaluation succeeded, now printing using
Rf_PrintValue:\n");
Rf_PrintValue(val);
UNPROTECT(1);
}
Rf_endEmbeddedR(0);
return 0;
}
$
$ gcc -o parseEvalS4 \> `${RPROG} CMD config --cppflags` \
> `${RPROG} CMD config --ldflags` parseEvalS4.c
$
$ ${RPROG} CMD ./parseEvalS4 --vanilla --silent
** I **: Executing command: show(5)
[1] 5
** I **: Evaluation succeeded, now printing using Rf_PrintValue:
[1] 5
** I **: Executing command: show(cbind2)
standardGeneric for "cbind2" defined from package "methods"
function (x, y)
standardGeneric("cbind2")
<environment: 0x8b34ef8>
Methods may be defined for arguments: x, y
** I **: Evaluation succeeded, now printing using Rf_PrintValue:
NULL
** I **: Executing command: cbind2
** I **: Evaluation succeeded, now printing using Rf_PrintValue:
Error: could not find function "show"
Error: unprotect(): only 0 protected items
$
-Deepayan
Look at the definition of PrintValue:
void PrintValue(SEXP s)
{
PrintValueEnv(s, R_BaseEnv);
}
That's not going to find show from R_BaseEnv. We need to get it from the
methods namespace.
On Sat, 7 Apr 2007, Deepayan Sarkar wrote:
> Hi,
>
> I think this is a bug (even though I can't find documentation
> explicitly saying that it should work). Basically, Rf_PrintValue(obj)
> fails when 'obj' is an S4 object that should be printed using
show()
> rather than print(). From the error message I'm guessing that the need
> to use show is detected correctly but then show is not found.
>
> "cbind2" in the code below is just a representative object, the
same
> holds for the few other S4 objects I have tried.
>
> The following uses r-devel on i686-pc-linux-gnu, but the results are
> same with R 2.4.1 (with suitable changes to the R_ParseVector call).
> On powerpc Linux I get a segfault.
>
>
> $ RPROG=R-devel
> $ ${RPROG} --version | head -1
> R version 2.6.0 Under development (unstable) (2007-04-06 r41080)
> $ export LD_LIBRARY_PATH=`${RPROG} RHOME`/lib
> $ cat parseEvalS4.c
>
> #include <Rinternals.h>
> #include <Rembedded.h>
> #include <R_ext/Parse.h>
>
> int main(int argc, char *argv[])
> {
> SEXP e, val;
> int i, errorOccurred;
> ParseStatus status;
> char *cmds[] = { "show(5)", "show(cbind2)",
"cbind2" };
>
> argv[0] = "R";
> Rf_initEmbeddedR(argc, argv);
>
> for (i = 0; i < 3; i++) {
> printf("** I **: Executing command: %s\n", cmds[i]);
> PROTECT(e = R_ParseVector(mkString(cmds[i]), -1, &status,
R_NilValue));
> val = eval(VECTOR_ELT(e, 0), R_GlobalEnv);
> printf("** I **: Evaluation succeeded, now printing using
> Rf_PrintValue:\n");
> Rf_PrintValue(val);
> UNPROTECT(1);
> }
>
> Rf_endEmbeddedR(0);
> return 0;
> }
>
> $
> $ gcc -o parseEvalS4 \
>> `${RPROG} CMD config --cppflags` \
>> `${RPROG} CMD config --ldflags` parseEvalS4.c
> $
> $ ${RPROG} CMD ./parseEvalS4 --vanilla --silent
> ** I **: Executing command: show(5)
> [1] 5
> ** I **: Evaluation succeeded, now printing using Rf_PrintValue:
> [1] 5
> ** I **: Executing command: show(cbind2)
> standardGeneric for "cbind2" defined from package
"methods"
>
> function (x, y)
> standardGeneric("cbind2")
> <environment: 0x8b34ef8>
> Methods may be defined for arguments: x, y
>
> ** I **: Evaluation succeeded, now printing using Rf_PrintValue:
> NULL
> ** I **: Executing command: cbind2
> ** I **: Evaluation succeeded, now printing using Rf_PrintValue:
> Error: could not find function "show"
> Error: unprotect(): only 0 protected items
> $
>
> -Deepayan
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>
--
Brian D. Ripley, ripley at stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595
Deepayan, you fail to load the methods package, so you cannot use S4. Eval "library(methods)" first then everything is fine. Cheers, Simon On Apr 7, 2007, at 7:33 PM, Deepayan Sarkar wrote:> Hi, > > I think this is a bug (even though I can't find documentation > explicitly saying that it should work). Basically, Rf_PrintValue(obj) > fails when 'obj' is an S4 object that should be printed using show() > rather than print(). From the error message I'm guessing that the need > to use show is detected correctly but then show is not found. > > "cbind2" in the code below is just a representative object, the same > holds for the few other S4 objects I have tried. > > The following uses r-devel on i686-pc-linux-gnu, but the results are > same with R 2.4.1 (with suitable changes to the R_ParseVector call). > On powerpc Linux I get a segfault. > > > $ RPROG=R-devel > $ ${RPROG} --version | head -1 > R version 2.6.0 Under development (unstable) (2007-04-06 r41080) > $ export LD_LIBRARY_PATH=`${RPROG} RHOME`/lib > $ cat parseEvalS4.c > > #include <Rinternals.h> > #include <Rembedded.h> > #include <R_ext/Parse.h> > > int main(int argc, char *argv[]) > { > SEXP e, val; > int i, errorOccurred; > ParseStatus status; > char *cmds[] = { "show(5)", "show(cbind2)", "cbind2" }; > > argv[0] = "R"; > Rf_initEmbeddedR(argc, argv); > > for (i = 0; i < 3; i++) { > printf("** I **: Executing command: %s\n", cmds[i]); > PROTECT(e = R_ParseVector(mkString(cmds[i]), -1, &status, > R_NilValue)); > val = eval(VECTOR_ELT(e, 0), R_GlobalEnv); > printf("** I **: Evaluation succeeded, now printing using > Rf_PrintValue:\n"); > Rf_PrintValue(val); > UNPROTECT(1); > } > > Rf_endEmbeddedR(0); > return 0; > } > > $ > $ gcc -o parseEvalS4 \ >> `${RPROG} CMD config --cppflags` \ >> `${RPROG} CMD config --ldflags` parseEvalS4.c > $ > $ ${RPROG} CMD ./parseEvalS4 --vanilla --silent > ** I **: Executing command: show(5) > [1] 5 > ** I **: Evaluation succeeded, now printing using Rf_PrintValue: > [1] 5 > ** I **: Executing command: show(cbind2) > standardGeneric for "cbind2" defined from package "methods" > > function (x, y) > standardGeneric("cbind2") > <environment: 0x8b34ef8> > Methods may be defined for arguments: x, y > > ** I **: Evaluation succeeded, now printing using Rf_PrintValue: > NULL > ** I **: Executing command: cbind2 > ** I **: Evaluation succeeded, now printing using Rf_PrintValue: > Error: could not find function "show" > Error: unprotect(): only 0 protected items > $ > > -Deepayan > > ______________________________________________ > R-devel at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel > >