[Rd] [External] REprintf could be caught by tryCatch(message)

[Tierney, Luke]

You can file it as a wishlist item in the bug trackign system. Without
a compelling case or a complete and well tested patch or both I doubt
it will rise to the top of anyone's priority list.

Best,

luke

On Sun, 15 Sep 2019, Jan Gorecki wrote:

> Thank you Luke for prompt reply.
> Is it possible then to request a new function to R C API "message"
> that would equivalent to R "message" function? Similarly as we now
> have C "warning" and C "error" functions.
>
> Best,
> Jan
>
> On Sun, Sep 15, 2019 at 5:25 PM Tierney, Luke <luke-tierney using uiowa.edu> wrote:
>>
>> On Sun, 15 Sep 2019, Jan Gorecki wrote:
>>
>>> Dear R-devel community,
>>>
>>> There appears to be an inconsistency in R C API about the exceptions
>>> that can be raised from C code.
>>> Mapping of R C funs to corresponding R functions is as follows.
>>>
>>> error    -> stop
>>> warning  -> warning
>>> REprintf -> message
>>
>> This is wrong: REpintf is like cat with file = stderr(). If this claim
>> is made somewhere in R documentation please report it a a bug.
>>
>>> Rprintf  -> cat
>>>
>>> Rprint/cat is of course not an exception, I listed it just for completeness.
>>> The inconsistency I would like to report is about REprintf. It cannot
>>> be caught by tryCatch(message). Warnings are errors are being caught
>>> as expected.
>>>
>>> Is there any chance to "fix"/"improve" REprintf so tryCatch(message)
>>> can catch it?
>>
>> No: this is behaving as intended.
>>
>> Best,
>>
>> luke
>>
>>> So in the example below catch(Cmessage()) would behave consistently to
>>> R's catch(message("a"))?
>>>
>>> Regards,
>>> Jan Gorecki
>>>
>>> catch = function(expr) {
>>>  tryCatch(expr,
>>>    message=function(m) cat("caught message\n"),
>>>    warning=function(w) cat("caught warning\n"),
>>>    error=function(e) cat("caught error\n")
>>>  )
>>> }
>>> library(inline)
>>> Cstop = cfunction(c(), 'error("%s\\n","a"); return R_NilValue;')
>>> Cwarning = cfunction(c(), 'warning("%s\\n","a"); return R_NilValue;')
>>> Cmessage = cfunction(c(), 'REprintf("%s\\n","a"); return R_NilValue;')
>>>
>>> catch(stop("a"))
>>> #caught error
>>> catch(warning("a"))
>>> #caught warning
>>> catch(message("a"))
>>> #caught message
>>>
>>> catch(Cstop())
>>> #caught error
>>> catch(Cwarning())
>>> #caught warning
>>> catch(Cmessage())
>>> #a
>>> #NULL
>>>
>>> ______________________________________________
>>> R-devel using r-project.org mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-devel
>>>
>>
>> --
>> Luke Tierney
>> Ralph E. Wareham Professor of Mathematical Sciences
>> University of Iowa                  Phone:             319-335-3386
>> Department of Statistics and        Fax:               319-335-3017
>>     Actuarial Science
>> 241 Schaeffer Hall                  email:   luke-tierney using uiowa.edu
>> Iowa City, IA 52242                 WWW:  http://www.stat.uiowa.edu
>

-- 
Luke Tierney
Ralph E. Wareham Professor of Mathematical Sciences
University of Iowa                  Phone:             319-335-3386
Department of Statistics and        Fax:               319-335-3017
    Actuarial Science
241 Schaeffer Hall                  email:   luke-tierney using uiowa.edu
Iowa City, IA 52242                 WWW:  http://www.stat.uiowa.edu