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

[Tim Keitt]

http://www.keittlab.org/

On Wed, May 25, 2016 at 10:43 AM, <luke-tierney at uiowa.edu> wrote:

> 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 agree -- I meant it was "perfectly fine" to remind us we need to check
pointers. Its really a documentation issue.

THK




>
> 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
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>

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