[R-pkg-devel] [FWD] [CRAN-pretest-archived] CRAN submission JuliaConnectoR 0.5.0

[Jeff Newmiller]

One could take the position that the library and require functions were a mistake to begin with and that all contributed packages should be accessed using ::...  or one could recognize that these functions are an expected feature of R at this point and then it is not defensible to ban the proposed approach of importing names as Stefan wants to. I don't think it is fair to require this higher level of specificity just because it involves use of attach.

That said, another feature of R packages is the integrated help system... importing Julia functions wholesale may lead to problems with consistency in navigating the help files. IMO it may be justifiable to ban this particular syntactic convenience to maintain some separation in the minds of users looking for help on these new functions, since the syntactic and semantic structure of functions from another language may not align well with normal R functions. But I am not familiar with Julia or Stefan's package or the support it brings in this area... I just disagree with banning a "library" lookalike function "just because" it happens to involve attach.

On April 6, 2020 8:40:12 AM PDT, Duncan Murdoch <murdoch.duncan using gmail.com> wrote:
>On 06/04/2020 11:25 a.m., Stefan Lenz IMBI wrote:
>> Yes, as I wrote earlier, I would like to imitate the behaviour of
>loading an R package
>> 
>>   juliaUsing("SomeJuliaPackage") # exports myJuliaFunction
>>   myJuliaFunction()
>> 
>> like R:
>> 
>>   library("MyRPackage") # exports myRFunction
>>   myRFunction()
>> 
>> I could return an environment, such that the call becomes
>> 
>>   attach(juliaUsing("SomeJuliaPackage"))
>>   myJuliaFunction()
>
>I wouldn't use it that way.  I'd write it as
>
>     sjp <- juliaUsing("SomeJuliaPackage")
>     sjp$myJuliaFunction()
>
>This is similar to the advice to use pkg::foo() rather than
>library(pkg) 
>followed by plain foo() in the code.
>
>Duncan Murdoch
>
>> 
>> But calling juliaUsing(), as it is now, takes care that if a package
>is imported a second time,
>> the first data base is removed via detach().
>> This way, users do not have to worry about calling juliaUsing()
>mutliple times in a script, same
>> as R users don't have to worry about calling library() multiple
>times.
>> If you call the code with attach() multiple times and do not detach,
>you get your screen cluttered with
>> warnings "xxx is masked by xxx".
>> So I would say it would decrease user-friendliness to return an
>environment.
>> I also want to make explicit, that the call to attach
>> occurs only once in my code, after creating the environment:
>> 
>>   envName <- paste0("JuliaConnectoR:", absoluteModulePath)
>>   if (envName %in% search()) {
>>   detach(envName, character.only = TRUE)
>>   }
>>   attach(funenv, name = envName)
>> 
>> This code is only called by juliaImport() and juliaUsing(), which
>aren't called by any other function of
>> the package
>> and are supposed to be called directly by the user.
>> 
>> Stefan
>>   
>> ----------------ursprüngliche Nachricht-----------------
>> Von: Duncan Murdoch [murdoch.duncan using gmail.com]
>> An: Dirk Eddelbuettel [edd using debian.org], Ben Bolker
>[bbolker using gmail.com]
>> Kopie: List r-package-devel [r-package-devel using r-project.org]
>> Datum: Mon, 6 Apr 2020 11:00:09 -0400
>> -------------------------------------------------
>>   
>>   
>>> On 06/04/2020 10:49 a.m., Dirk Eddelbuettel wrote:
>>>>
>>>> On 6 April 2020 at 08:38, Ben Bolker wrote:
>>>> | Just reply to the CRAN maintainers and explain this situation.
>It¨s
>>>> | slightly buried, but the e-mail you received does say:
>>>> |
>>>> | > If you are fairly certain the rejection is a false positive,
>please reply-all to this
>>>> | > message and explain.
>>>>
>>>> True, but this misses the "Letter of the law" versus the "Spirit of
>the law".
>>>>
>>>> It might be worth mentioning that use of attach() is seen, to find
>one poor
>>>> analogy, pretty much like use of global variables these days. "Just
>because
>>>> you could does not mean you should".
>>>>
>>>> See e.g. one of the first google hits for 'r do not use attach'
>here:
>>>>
>https://stackoverflow.com/questions/10067680/why-is-it-not-advisable-to-use-attach-in-r-and-what-should-i-use-instead
>>>
>>> I don't have a strong opinion on this: the proposed use seems to be
>no
>>> worse than library() or require(). Those are fine for users to use,
>but
>>> are discouraged in a package. If the attach() never happens without
>an
>>> explicit request from the user (and that's what it sounds like), I'd
>say
>>> it's probably okay.
>>>
>>> However, there is an easy workaround: just return the environment
>>> without attaching it. Then the user has the choice of attaching it,
>or
>>> using it as a prefix when they call the functions in it. So it's not
>as
>>> though this will destroy the utility of the package if Stefan isn't
>>> allowed to call attach().
>>>
>>> Duncan Murdoch
>>>
>>> ______________________________________________
>>> R-package-devel using r-project.org mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-package-devel
>>>
>> 
>>
>
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Sent from my phone. Please excuse my brevity.