[R] Writing packages with `methods' package

[John Chambers]

The problem here is that the standard R way of attaching a package is to
source in the R code; when the code contains setMethod() calls and the
like, the result is to store the resulting definitions in the global
environment.

When you're writing packages using methods, you essentially always want
to use an alternative installation for the package, which creates a
binary image when R INSTALL runs.   This image is loaded when the
package is attached by calling library(), and the objects for methods,
etc. are in the package database,as you would like.

There's a paragraph in the online documentation for INSTALL that
describes what to do.  (if you want a quick fix, just touch an empty
file install.R in the package's top level directory.)

When you run INSTALL, you should see a line:

** save image

in the printout.  And no files generated in the global environment from
calling library()

Regards,
 John Chambers

Roger Peng wrote:
> 
> I'm trying to write a package which uses classes/methods as defined in the
> `methods' package.  I have a single .R file which defines the class and
> various methods for that class.  At the top of the file I have
> 
> require(methods)
> 
> and then
> 
> setClass("myclass", ...)
> setGeneric("intersect")
> setMethod("intersect", "myclass", function(x,y) ...)
> 
> I noticed that when I build the package and subsequently load it via
> library(), the methods show up in the global workspace, which is not quite
> what I wanted.
> 
> In general, is there any documentation on building packages with the
> `methods' package (i.e. is it any different from building packages without
> `methods'?) or perhaps an R-help thread I should look for?
> 
> In short, how should I setup my package so that my methods do not show up
> in the global workspace?
> 
> Thanks,
> 
> -roger
> _______________________________
> UCLA Department of Statistics
> rpeng at stat.ucla.edu
> http://www.stat.ucla.edu/~rpeng
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
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-- 
John M. Chambers                  jmc at bell-labs.com
Bell Labs, Lucent Technologies    office: (908)582-2681
700 Mountain Avenue, Room 2C-282  fax:    (908)582-3340
Murray Hill, NJ  07974            web: http://www.cs.bell-labs.com/~jmc