[Rd] Use of R_PROFILE.R / install.R

[Kurt Hornik]

>>>>> Prof Brian Ripley writes:

> According to R-exts:

>   The second purpose for @file{install.R} is to hold code that needs
>   to be executed each time the package is attached, after the image is
>   loaded.  Few packages have a need for such code so @file{install.R}
>   is normally an empty file.

>   The optional file @file{R_PROFILE.R} is executed before the code in
>   the @file{R} subdirectory and should be used to set up an
>   environment needed only to evaluate the code (which is run with the
>   @option{--vanilla} command-line flag).  Very few packages will need
>   such code.  Indeed, both @file{install.R} and @file{R_PROFILE.R}
>   should be viewed as experimental; the mechanism to execute code
>   before attaching or installing the package may change in the near
>   future.

> (Actually it's during loading, not attaching, a namespace, for packages
> with namespaces.)

> Looking on CRAN, it seems that two packages use R_PROFILE.R for
> `options(echo=FALSE)', which does not do anything useful AFAICS.  A
> non-empty install.R is used for

> require(methods)
> require(boot)
> require("Hmisc")
> data(Wcrit.R)

> and that's not the intention (and in particular require() should have its 
> return value checked!) -- this is best done in .First.lib/.onLoad.

> One problem is that the package has no way to prevent a saved image being 
> forced with INSTALL --save.


> Since this mechanism is a maintenance nightmare (especially with
> lazy-loading +/- saving images) I propose we drop it for 2.0.0.
> Instead, just as for lazy-loading, we should have a field in the
> DESCRIPTION file, with

> SaveImage: yes

> forcing saving the image, and any other value forcing not saving it.

Fine with me.

Can we perhaps agree to allow both yes/no and true/false for such
logical package DESCRIPTION metadata (and also irrespective of case)?

-k

> Note that most packages which currently save an image probably want to 
> use lazy-loading instead and so should have LazyLoad: yes in their 
> DESCRIPTION file.

> The proposed change is not backwards compatible but affects very few CRAN 
> packages, for all of which there is better solution that is backwards 
> compatible.  I have not looked at BioConductor or elsewhere, so please 
> will package authors let us know of any examples where R_PROFILE.R or 
> install.R is essential (and why).

> -- 
> Brian D. Ripley,                  ripley at stats.ox.ac.uk
> Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
> University of Oxford,             Tel:  +44 1865 272861 (self)
> 1 South Parks Road,                     +44 1865 272866 (PA)
> Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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