[Rd] why is \alias{anRpackage} not mandatory?

[Duncan Murdoch]

On 06/10/2008 8:06 AM, Thomas Petzoldt wrote:
> Duncan Murdoch wrote:
>> Thomas Petzoldt wrote:
>>> Dear R developers,
>>>
>>> if one uses package.skeleton() to create a new package, then a file 
>>> anRpackage.Rd with the following entries is prepared:
>>>
>>> \name{anRpackage-package}
>>> \alias{anRpackage-package}
>>> \alias{anRpackage}
>>> \docType{package}
>>>
>>>
>>> Packages created this way have a definite entry or overview page, so:
>>>
>>> ?anRpackage
>>>
>>> gives new users of a certain package a pointer where to start reading.
>>>
>>> This is similar for packages which have the same name as their main 
>>> workhorse function, e.g. zoo or nlme, but there are many packages 
>>> which don't have an \alias{anRpackage}.
>>>
>>> "Writing R Extensions", sec. 2.1.4 says:
>>>
>>> "Packages may have an overview man page with an \alias 
>>> pkgname-package, e.g. `utils-package' for the utils package, when 
>>> package?pkgname will open that help page. If a topic named pkgname 
>>> does not exist in another Rd file, it is helpful to use this as an 
>>> additional \alias."
>>>
>>> My question: what speaks against making this sentence more pronounced 
>>> and why not NOTE-ing a missing package alias in the package check?
>>>
>>>   
>> Not everybody likes the idea of the overview man page, so when I wrote 
>> that I left it weak.  Some of the disadvantages:
> 
> You speak about the disadvantages but there are, of course, obvious 
> advantages. Almost all scientific papers start with an abstract, why not 
> requesting one for software packages, at least for new ones?

We already require one in the DESCRIPTION file for all packages, which 
you can see with

library(help=packagename)

This is related to my first two points:  people have already done this 
work so they are reluctant to do it again, and duplicate information is 
a bad idea.

I think the R help system is too fragmented:  it's hard to discover all 
the different types of help that are already there (Rd files, 
DESCRIPTION files, vignettes, the manuals, NEWS, CHANGES, ChangeLogs, 
SVN logs, source comments, mailing lists, web pages and publications, 
...).  I think having a ?packagename man page is a good place for a 
single starting point, and I consider packages without one to be poorly 
documented.  But obviously, not everyone agrees.

>> - there are lots of packages without one, so this would create a lot of 
>> work for people to add them.
> 
> No, I don't think that this is too much work. Positively speaking, it's 
> one small contribution to bring more light into the exponentially 
> growing haystack.

I agree, and I even added these to all the packages under my control: 
but there are hundreds of package authors, and some have different 
priorities than you and me.

> What about starting to advertise the use of \alias{anRpackage}, i.e. a 
> short article in R News and subsequently an email to the developers.

I would have thought that putting this into NEWS and Writing R 
Extensions was the right way to advertise it.  If people don't read 
those, why would you think they'll read R News?  But more is better, so 
go ahead and submit an article to R News.

I don't like robot mailings, so I wouldn't appreciate an email on this. 
  I don't recommend that you send one.


> 
>> - the ones that do exist tend to include outdated information.  People 
>> update the DESCRIPTION file but forget to update the corresponding 
>> information in the overview.
> 
> This is in fact a problem. Suggestions:
> 
> - propose basic style guidelines (in an R-News article)
> - allow variables in .Rd files (your idea to allow "Sweave like 
> constructs" may be even better). In addition to entries from 
> DESCRIPTION, one can think also about importing data from CITATION and 
> possibly also from other resources.
> 
>> - in general there's a lot of dissatisfaction with the Rd format, so 
>> there's reluctance to invest any more effort in it.
> 
> You are right, .Rd has its limitations, but as you say, there is nothing 
> better available in the moment. (BTW: I heard rumours at useR! about 
> discussions on a meta documentation format? Is there any public 
> information about this??)

I first heard proposals for a replacement format at DSC 2001.  I don't 
know of anything concrete.

Duncan Murdoch

> 
>> It would probably be a good idea to generate one automatically if not 
>> provided by the author, at build or install time:  this would address 
>> the first point.  
> 
> A reasonable idea -- at least if combined with a motivating request to 
> package authors to provide an own one.
> 
>> I've been slowly working on some fixes that address 
>> the second point.  (The current idea is to use Sweave-like constructs to 
>> import things from the DESCRIPTION file at install time.)  There's no 
>> way to address the third point other than providing a better format, and 
>> I don't see any prospect of that happening.
> 
> So if there are no advances in that direction I see no other choice than 
> using the existing mechanisms! Recently, I had several contacts with 
> package authors who were not even aware about the possibility of 
> providing a package information .Rd file.
> 
>> Duncan Murdoch
>>
> 
> Thanks, Thomas P.