On 8/30/2006 12:28 PM, Paul Gilbert wrote:
> Duncan Murdoch wrote:
>> On 8/30/2006 4:44 AM, Martin Maechler wrote:
>>>>>>>> "FrL" == friedrich leisch <[EMAIL PROTECTED]>
>>>>>>>> on Wed, 30 Aug 2006 09:34:13 +0200 (MEST) writes:
>>> >> Duncan Murdoch <[EMAIL PROTECTED]> writes:
>>> >>> I think we need an option to R CMD check rather than a new field in
>>> the
>>> >>> DESCRIPTION. Currently a package could be mentioned for any of
>>> these
>>> >>> reasons:
>>> >>>
>>> >>> 1. To make functions, examples or vignettes work
>>> >>> 2. To allow optional functionality in functions, examples or
>>> vignettes.
>>> >>> 3. Because it contains complementary functions.
>>> >>>
>>> >>> I don't think we really need to worry about 3: it should be
>>> contained
>>> >>> in 1 or 2, if reasonably complete examples are given.
>>> >>>
>>> >>> Case 1 is handled by Depends.
>>> >>
>>> >> I think there is an important distinction between a dependency needed
>>> >> for the package to function and a dependency needed to demonstrate
>>> >> said functionality via an example or vignette. The former is what
>>> >> Depends is about, the latter is something else (Suggests).
>>>
>>> FrL> Sorry to join in late, I am at the Compstat conference and have
>>> limited
>>> FrL> email access. What Seth describes in the above paragraph is
>>> exactly what I
>>> FrL> had in mind when splitting the single Depends field we had into
>>> Depends
>>> FrL> and Suggests: Depends are a necessity to run the package, Suggests
>>> is nice
>>> FrL> to have but not necessary. If you know how to use a package you
>>> may the
>>> FrL> decide not to install a package that is only suggested, but
>>>
>>> FrL> * may not be interested to execute the examples,
>>> FrL> * know that you never need the extra functionality
>>> FrL> * ...
>>>
>>> FrL> so it should not be auto-installed unless you ask for
>>> FrL> it (the default could also be the other way round, the
>>> FrL> point is that it should be possible to have package foo
>>> FrL> but not the packages it only suggests). On CRAN we
>>> FrL> check with all suggestions to test all bits and pieces,
>>> FrL> having an option in R CMD check to test only with
>>> FrL> suggests may be nice, if there is use for it.
>>>
>>> Yes.
>>> However, I see two (related) problems with the current 'Suggests'
>>> and that's why I opened this thread proposing to have a
>>> (what I now would want to simply call) 'canUse' :
>>>
>>> 1) For 'R CMD check' (and hence CRAN checking),
>>> Packages in 'Suggests' must be require()able, and
>>> hence all testing only happens *with* the suggested packages
>>> being there, and not without.
>>>
>>> 2) "Suggests" suggests to the human reader of DESCRIPTION that
>>> the package authors suggest to also install the packages listed
>>> there.
>>> Now there are cases, I (as package author) want to show some
>>> stuff, or even provide compatibility functionality for some
>>> packages that are related to mine, but which I really do not ``suggest''
>>> to also be installed, e.g., because the other packages do
>>> similar stuff as mine, but I believe my package to be
>>> superior. In such a case, I may, e.g., want to provide
>>> functions for porting the other package classes to my package's.
>>>
>>> Duncan Murdoch has proposed to take care of "1)" by
>>> still only use 'Suggests' but adding another option to 'R CMD
>>> check', let's say --no-suggests which would run all the
>>> checks without having the suggested packages available
>>> --- something not quite easy to implement, BTW:
>>> Imagine the typical windows users who (AFAICS) always only use
>>> one library into which they install all packages.
>>> How do you want the
>>> if( require(<my_suggested_package>) ) {
>>> ...
>>> }
>>> clause *not* to be triggered in such a case ?
>>
>> I would expect require to return FALSE. This could be done by check
>> installing a new version of require() (as it installs new T and F), or
>> by the standard require() being modified to check a stop list before
>> acting (I'd prefer this, because it would make it easier for developers
>> to experiment with functions in different environments), or by playing
>> around with the names of things in the library (probably not workable on
>> Windows), etc.
>>
>> I think the default check behaviour on CRAN should be my middle case:
>> test based on what is currently installed, don't require packages listed
>> in Suggests to be installed. I'm not sure if that should be the default
>> behaviour for R CMD check at the command line: as Kurt said, usually a
>> developer wants to check all of the code.
>>
>>> I do agree quite a bit that such a '--no-suggests' option would
>>> be very useful for 'R CMD check' -- in addition to my proposal.
>>
>> I think the other extreme (which I think is there now as
>> _R_CHECK_FORCE_SUGGESTS_) is also important.
>>
>>> Further, I think "2)" above is not taken care of anyway.
>>> After all the interesting statements and alternative proposals,
>>> I'm still proposing to introduce a 'canUse' field for DESCRIPTION
>>> which
>>> a) has a "human-readable intent" of being weaker than 'Suggests'
>>> b) will not require its packages to be available for R CMD check
>>> c) conveys extra information about the package's context, to humans, and
>>> d) will potentially be used in automated or semi-manual
>>> ``R package database management''
>>
>> I think d) is important, but I think there are too many variations on a)
>> and c) to hope that this would be used consistently. As Fritz said, the
>> thing he can remember (and what I would remember) is whether a package
>> is mandatory or optional. Fine variations within "optional" are just
>> too hard to define clearly in a two-level classification.
>>
>> On the other hand, they are relatively easy to convey in clearly written
>> documentation. So I'd still recommend that we stay with just Depends
>> and Suggests, but encourage authors to document what they mean by
>> "Suggests".
>
> The problem I see here is that this is a change from the status quo,
> which is likely to make a real mess for some time.
I'm not sure what your "this" refers to. Was it my suggestion or
Martin's? Must be his, I never make a real mess :-)
Duncan Murdoch
> The status quo is
> that packages in Depends and Suggests are needed to check examples and
> vignettes. I would not change this without a very good reason. It would
> be best to put other suggestions of extensions, that some users may want
> to use, somewhere else. The current situation is that these suggestions
> are sprinkled in Rd files, vignettes, web pages, etc. This situation is
> not too bad, but it might be nice to have some place users would expect
> to find this information. However, changing the meaning of Suggests to
> be developer defined does not strike me as an improvement.
>
> Paul Gilbert
>>
>> Duncan Murdoch
>>
>>> Martin
>>>
>>> FrL> Ad the wording in the manual: obviously that is not
>>> FrL> optimal (otherwise no need for parts of this email
>>> FrL> thread), perhaps somebody else than the original author
>>> FrL> (=me) could try to improve it for 2.4 after this
>>> FrL> clarifications? Otherwise I will give it a shot next
>>> FrL> week after I return from Rome.
>>>
>>> ______________________________________________
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>>
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> La version française suit le texte anglais.
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