[Rd] how to store package options over sessions?

[Dirk Eddelbuettel]

On 20 November 2010 at 17:12, Mark Heckmann wrote:
| Hi,
| I posted this a week ago on r-help but did not get an answer. So I hope that someone here can help me:
| I want to define some options for my package the user may change.
| It would be convenient if the changes could be saved when terminating  
| an R session and recovered automatically on the next package load.
| 
| Is that possible and if yes, is the standard way to implement this?

First off:

   R> fortunes:::fortune("yoda")
   
   Evelyn Hall: I would like to know how (if) I can extract some of the
   information from the summary of my nlme.
   Simon Blomberg: This is R. There is no if. Only how.
      -- Evelyn Hall and Simon 'Yoda' Blomberg
         R-help (April 2005)
   
   R> 

Secondly, what you ask is necessarily rather OS-dependent. So of course it
can be done, but probably in way that depend on your local circumstance.

Thirdly, and to make this a little more helpful, I frequently use the RSQLite
package to cache data across sessions and invocations. For a large example,
consider the CRANberries feed (http://dirk.eddelbuettel.com/cranberries/)
which stores in SQLite what the the state of the (CRAN) world was the last it
got woken up by crontab.  I also have a few smaller ad-hoc things at work
that do similar things.

Depending on your local circumstances you may make this 'cache' of stateful
information read or read/write, make it a file on NFS or CIFS or WebDAV, make
it a database that can be read as file or over sockets and so.  

And Yoda still rules.

Dirk

-- 
Dirk Eddelbuettel | edd at debian.org | http://dirk.eddelbuettel.com