[Rd] Suggestion: mkString(NULL) should be NA

[luke-tierney at uiowa.edu]

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/
>
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>
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-- 
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
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