[Rd] Is ALTREP "non-API"?

[Simon Urbanek]

> On Apr 24, 2024, at 12:52 AM, Hadley Wickham <h.wickham using gmail.com> wrote:
> 
>> 
>> 
>> 
>>>> ALTREP is part of the official R api, as illustrated by the presence of
>>>> src/include/R_ext/Altrep.h. Everything declared in the header files in
>> that
>>>> directory is official API AFAIK (and I believe that is more definitive
>> than
>>>> the manuals).
>>>> 
>>> 
>>> That is not true at all - the presence of header does not constitute
>> declaration of something as the R API. There are cases where internal
>> functions are in the headers for historical or other reasons since the
>> headers are used both for the internal implementation and packages. That's
>> why this is in R-exts under "The R API: entry points for C code":
>>> 
>>> If I understand your point correctly, does this mean that
>> Rf_allocVector() is not part of the "official" R API? It does not appear to
>> be documented in the "The R API: entry points for C code" section.
>>> 
>> 
>> It does, obviously:
>> https://cran.r-project.org/doc/manuals/R-exts.html#Allocating-storage-1
> 
> 
> I'm just trying to understand the precise definition of the official API
> here. So it's any function mentioned in R-exts, regardless of which section
> it appears in?
> 
> Does this sentence imply that all functions starting with alloc* are part
> of the official API?
> 

Again, I can only quote the R-exts (few lines below the previous "The R API" quote):


We can classify the entry points as
API
Entry points which are documented in this manual and declared in an installed header file. These can be used in distributed packages and will only be changed after deprecation.


It says "in this manual" - I don't see anywhere restriction on a particular section of the manual, so I really don't see why you would think that allocation is not part on the API.

Cheers,
Simon




>> For many purposes it is sufficient to allocate R objects and manipulate
> those. There are quite a
>> few allocXxx functions defined in Rinternals.h—you may want to explore
> them.
> 
> Generally, things in a file with "internal" in its name are internal.
> 
> Hadley
> 
> -- 
> http://hadley.nz
> 
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