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

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 at 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

--
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 at uiowa.edu
Iowa City, IA 52242                 WWW:  http://www.stat.uiowa.edu