On Nov 11, 2011, at 10:08 AM, Simon Urbanek wrote:
>
> On Nov 10, 2011, at 6:24 PM, KR wrote:
>
>> First of all thanks a lot to you both for all the replies, they have been of
>> great help to me!
>>
>> I got the basic embedding running, however I still have some issues to solve
>> in
>> order to complete the interface to R I am working on:
>>
>> 1. I initialize with Rf_initEmbeddR().
>> - Is there a way to have more than one R "state" (per single thread)? Or is
>> everything necessarily global?
>
> There are no threads in R. You have only one, global instance of R.
>
>
>> - I also read somewhere that the fpu settings may be touched. Is there a way
>> to
>> make sure that this is not the case? Is this related to fpu_setup()?
>>
>
> All following answers assume that you're not running REPL. If you did, you
> would get all the errors on the console callback, so I'm assuming that's not
> what you want.
>
>
>> 2. I create a string and parse it via Rf_mkString() and R_parseVector() (yes
>> I
>> protect/un-protect the SEXPs).
>> - Is it possible to obtain the precise error message, like "unexpected
>> symbol
>> in..." (as would be reported by R.exe) in case of error as a const char*
>> string?
>
> AFAIR you have to evaluate parse(text=...) for that, there is no C-level
> access to parser errors.
>
>
>> - If I pass a wrongly escaped string (for instance 'ggsave("C:\gtest.png")',
>> please notice the missing \) I get on stderr: Error '\g' is an unrecognized
>> escape and I get a crash. This does not happen if for instance i try to
>> parse
>> 'rnorm(10a10)' in which case I get the error flag and the NULL ptr return. I
>> suspect I need to initialize something / set a callback to avoid this but I
>> am
>> not sure...
>>
>
> If you get a crash, you're not setting up you R correctly. If your R quits
> then you are in non-interactive mode and you didn't setup an error handler.
>
>
>> 3. I eval with R_tryEvalSilent().
>> - Again, is it possible to obtain the precise error message in case of
>> evaluation error as would be reported from R.exe?
>>
>
For completeness: geterrmessage() R function returns the last error message
> I prefer using Rf_eval() and try(..., silent=TRUE) - you can check on the
> class of the result to see if there was an error.
>
>
>> 4. Regarding the returned result of evaluation.
>> - What is the correct way to obtain a const char* string representing the
>> result
>> as would be "printed" in the R shell by executing a command (for instance
>> "summary(c(1,2,3))") ?
>
> See ?capture.output
>
>
>> - Why is the return type (as reported from typeof in R and TYPEOF in C) of
>> "summary(c(1,2,3))" a double?
>>
>
> Because the constants 1, 2 and 3 are all doubles. For example 1L is an
> integer and "1" is a string.
>
> BTW: you are asking a lot of questions the are answered in the Rserve FAQ
> (since what you do is exactly what Rserve provides) so you may want to have a
> quick look:
> http://rforge.net/Rserve/faq.html
>
> Cheers,
> Simon
>
>
>
>> Any help / feedback on these issues would be greatly appreciated.
>>
>> Thanks again.
>>
>> ______________________________________________
>> R-devel@r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-devel
>>
>>
>
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