Suggestion: mkString(NULL) should be NA

On Wed, 25 May 2016, Tim Keitt wrote:

On Wed, May 25, 2016 at 7:22 AM, Michael Lawrence <

lawrence.michael at gene.com

wrote:

On Wed, May 25, 2016 at 4:23 AM, Jeroen Ooms <jeroen.ooms at stat.ucla.edu>

wrote:

I'm not disagreeing with what's been said in this thread, but I can't help
but recall that I brought up this exact issue probably 15 years ago and
was
told (by Brian, I believe) "don't do that" (pass a null pointer), which
was
perfectly fine. The real issue was not the behavior but that it was not
documented or consistent. I've lived by the mantra since that you can
never
trust a pointer in R code. User must always check for NULL.

In _C_ code.  This is true whether you are calling into the R C API or
any other C library: you as the C programmer need to make sure either
that passing NULL is OK or make sure you don't do that.

I wouldn't object to mkXXX checking for NULL and signaling an error
instead of segfaulting, but good C code calling mkXXX should still
typically do its own check and handle the situation in an appropriate
way.

Best,

luke

I just wrote my own functions mkXXX_safe that wrap the internals and check
the pointer.

THK

http://www.keittlab.org/

        [[alternative HTML version deleted]]

--
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