From tkeitt at utexas.edu  Thu May 26 00:36:16 2016
From: tkeitt at utexas.edu (Tim Keitt)
Date: Wed, 25 May 2016 17:36:16 -0500
Subject: [Rd] Suggestion: mkString(NULL) should be NA
In-Reply-To: <alpine.LFD.2.20.1605251032520.4743@itasca.stat.uiowa.edu>
References: <CABFfbXt7raZDRaGP+T=XWKeBZq8oh88FRh8+Xj7jFkf_VFspsA@mail.gmail.com>
	<CABFfbXu0LTrSy9Qq5mouq6fX=nN=NF9xshtM8Q9khYn3cWtEQw@mail.gmail.com>
	<CADwqtCP2O7zUSJ3BHvYbkD25EyJPyj9LhdazJf5UzELVW1_9-w@mail.gmail.com>
	<CABFfbXtUHYepH93PZrYktNbFfNX-Y8iF5Pk6DYOgUFk=MGK7pA@mail.gmail.com>
	<CADwqtCNLmskyk1v_syjGeH6H4tnLTAkihKh8c0gHuc7nHDqpDQ@mail.gmail.com>
	<22341.32520.155909.439980@stat.math.ethz.ch>
	<CABFfbXtVi09hpKc-FbgWBbPkJrU1V2bNdsTHqBEdxFK2rfmpog@mail.gmail.com>
	<CAOQ5NyftzeVpbRGxM0Jd6=8f00VENWnAmW2oBQchALqvzKJOmA@mail.gmail.com>
	<CANnL8gpKeY7XVeLf+WyKCT_C2yjGo69_t25r-LTdmVu93_6eCw@mail.gmail.com>
	<alpine.LFD.2.20.1605251032520.4743@itasca.stat.uiowa.edu>
Message-ID: <CANnL8gqzCf5B7G=Xq3FiOYFq7msSBYbGbwBEU-gfgob3Wc9awA@mail.gmail.com>

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/
>>
>>         [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> R-devel at 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 at uiowa.edu
> Iowa City, IA 52242                 WWW:  http://www.stat.uiowa.edu
>

	[[alternative HTML version deleted]]



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