[R] Required Packages etiquette

[Liaw, Andy]

[This is probably more appropriate for R-devel rather than R-help.]

IMHO the criterion for requiring a package (say `X') is that, if some
function(s) in your package can not perform its tasks correctly without
something in `X', then you should list `X' as required.  You can not assume
the user will have `X' loaded (or even installed) if you do not list it as
`required'.

Andy

> From: GiusVa
> 
> Dear friends,
> 
> I am writing a package that I think may be of interest to 
> many people so I
> am in the process to build-check-write-thedocumentation for it. 
> 
> I have some questions regarding the "rules"  that a package
> should abide in order to be consistent with the other 
> packages on CRAN.
> I have read and reread the Writing R extension manual and googled the
> mailing list and I have found answers to many questions, but some have
> been left unanswered. Sorry if they may seem trivial, but I have
> joined the R community only 4 months ago and I still I do not have a
> feeling of what is the right course of action.
> 
> Questions:
> 
> 1) the package I am writing ( MYPKG throughout the rest of 
> the message)
> makes use of many packages. Some of them are fundamental to MYPKG and
> are pervasive, i.e. without them the package will not work and many
> functions are used. For these class of packages I (think) know what to
> do.
> 
> The second class of package interests MYPKG only for specific
> task. For example, I need the "coda" package if one wants to use a
> specific function of MYPKG that produces a MCMC chain. What is the
> best way to require the package? Inside the function that request it?
> 
> The relation between the  third class of packages and MYPKG is very
> tricky. For example, from the MASS package MYPKG only uses "ginv" to
> get the generalized inverse. "ginv" is an important function, i.e. it
> is used in many functions. Do I have to require MASS? Or should I just
> include only "ginv" in the package?
> 
> Thank you for patience.
> 
> Giuseppe
> 
> ------------------------------------------------------------
> |Giuseppe Ragusa
> |University of California, San Diego
> |9500 Gilman Dr. 0508
> |La Jolla, CA 92093
> 
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