[Rd] 'CanMakeUseOf' field

[Seth Falcon]

Duncan Murdoch <murdoch at stats.uwo.ca> 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).

> An author should check case 2 both with and without the suggested 
> package.  A user  might be satisfied with a simple check "as things 
> currently stand", or might want a stringent check like the author wants. 
>   The author can't know that, because it will depend on the user.
>
> So I don't think this is something that should be changed in 
> DESCRIPTION.  There should be an option to R CMD check to include or 
> exclude packages mentioned in the Suggests entry.  (I'd suggest a 3 
> level option:  check as though they are not available, check as 
> currently installed, require that they be available.)

I like this approach and agree in general that a solution involving
changes to R CMD check might be the best as opposed to adding fields.

+ seth