R devel - Nov 2010 - how to store package options over sessions?

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?

Thanks,
Mark

–––––––––––––––––––––––––––––––––––––––
Mark Heckmann
Dipl. Wirt.-Ing. cand. Psych.
Celler Straße 27
28205 Bremen
Blog: www.markheckmann.de
R-Blog: http://ryouready.wordpress.com






	[[alternative HTML version deleted]]

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

I'm not sure why it was not mentioned do far, but the most obvious solution
is to create a special object in the workspace (usually a hidden environment or
a list - e.g. .myPackage.options.env). One advantage is that the user has full
control over whether it should be save or not as it's tied to the workspace.
On load the package can look for it and use it if it is what's expected
(e.g., it may be worth using a specific class).

That said, in either case I think it's important to make it optional and
document it well, because leaving files or objects around when not expected is
impolite to say the least.

Cheers,
Simon


On Nov 20, 2010, at 11:12 AM, 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?
> 
> Thanks,
> Mark
> 
> ???????????????????????????????????????
> Mark Heckmann
> Dipl. Wirt.-Ing. cand. Psych.
> Celler Stra?e 27
> 28205 Bremen
> Blog: www.markheckmann.de
> R-Blog: http://ryouready.wordpress.com
> 
> 
> 
> 
> 
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel

On Sat, Nov 20, 2010 at 11:12 AM, Mark Heckmann <mark.heckmann at gmx.de>
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?
>
You can use options and getOptions for this.  The user can place an
options command in their .Rprofile or just enter it into their session
to override the defaults.  See ?options .  For example, in the gsubfn
package look at the engine argument:
> library(gsubfn)
Loading required package: proto
> args(gsubfn)
function (pattern, replacement, x, backref, USE.NAMES = FALSE,
    ignore.case = FALSE, engine = getOption("gsubfn.engine"),
    env = parent.frame(), ...)

The user can put an options(engine = "...whatever...") in their
.Rprofile file or can enter it interactively into R.  If not,
getOption("gsubfn.engine") returns NULL and the gsubfn package can
check whether engine was passed as a NULL and supply a default.

-- 
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GKX Group, GKX Associates Inc.
tel: 1-877-GKX-GROUP
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