[Rd] Rf_PrintValue problem with methods::show

[Simon Urbanek]

Deepayan,

don't mind my last mail - one shouldn't write e-mails before the  
first cup of coffee in the morning ;).. "methods" used to be excluded  
from the embedded startup (AFAIR), but that's no longer the case, so  
it must be something else. Sorry for the noise (I'm off to get the  
coffee :P).

Cheers,
Simon

On Apr 8, 2007, at 8:31 AM, Simon Urbanek wrote:

> 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
>>
>>
>