R devel - Sep 2017 - Please avoid direct use of NAMED and SET_NAMED macros

> To allow for future changes in the way the need for duplication is
> detected in R internal C code, package C code should avoid direct
> use of NAMED,and SET_NAMED, or assumptions on the maximal value
> of NAMED. Use the macros MAYBE_REFERENCED, MAYBE_SHARED, and
> MARK_NOT_MUTABLE instead. These currently correspond to
> 
> MAYBE_REFERENCED(x):   NAMED(x) > 0
> MAYBE_SHARED(x):       NAMED(x) > 1
> MARK_NOT_MUTABLE(x):   SET_NAMED(c, NAMEDMAX)
> 
> Best,
> 
> luke

Checking https://cran.r-project.org/doc/manuals/r-release/R-exts.html
shows that currently there is no mention of these macros in the
documentation for package writers.  Of course, the explanation of
NAMED there also does not adequtely describe what it is supposed to
mean, which may explain why it's often not used correctly.

Before embarking on a major change to the C API, I'd suggest that you
produce clear and complete documention on the new scheme.

    Radford Neal

On Sat, 2 Sep 2017, Radford Neal wrote:
>> To allow for future changes in the way the need for duplication is
>> detected in R internal C code, package C code should avoid direct
>> use of NAMED,and SET_NAMED, or assumptions on the maximal value
>> of NAMED. Use the macros MAYBE_REFERENCED, MAYBE_SHARED, and
>> MARK_NOT_MUTABLE instead. These currently correspond to
>>
>> MAYBE_REFERENCED(x):   NAMED(x) > 0
>> MAYBE_SHARED(x):       NAMED(x) > 1
>> MARK_NOT_MUTABLE(x):   SET_NAMED(c, NAMEDMAX)
>>
>> Best,
>>
>> luke
>
>
> Checking https://cran.r-project.org/doc/manuals/r-release/R-exts.html
> shows that currently there is no mention of these macros in the
> documentation for package writers.  Of course, the explanation of
> NAMED there also does not adequtely describe what it is supposed to
> mean, which may explain why it's often not used correctly.
As of yesterday they are mentioned in the R-devel version of this
manual, which will make it to the web in due course.
> Before embarking on a major change to the C API, I'd suggest that you
> produce clear and complete documention on the new scheme.
>
>    Radford Neal
>
-- 
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
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