hook for when R quits

On Fri, Mar 11, 2011 at 11:07 AM, Prof Brian Ripley
<ripley at stats.ox.ac.uk>  wrote:
 On Fri, 11 Mar 2011, Duncan Murdoch wrote:

 On 11/03/2011 1:37 PM, Michael Lawrence wrote:
 Thanks for the suggestion, but I don't think that R finalizes all of its
 objects when it quits. At least a simple test suggests that on Linux.
 Did you use onexit=TRUE?  On Windows that appears to work...
Agree - here an object finalizer is more appropriate (different from
an end-of-session hook).

 It does work: RODBC makes extensive use of it, for exactly the purpose you
 describe (or rather, the C_level equivalent of 'it').
In help(reg.finalizer) it says:

   'onexit': logical: should the finalizer be run if the object is
still uncollected at the end of the R session?

What environments, objects, search path etc are available when the
finalizer is called this way when R exits?  Is safe to always add
'onexit=TRUE' (which now defaults to FALSE), or should I expect an
"exceptional" R system that the finalizer needs to account for?
To be very conservative, I would assume that nothing in R is available 
other than things that are stored in that environment.  That's probably 
not true, but it would be safe.  This mechanism is for finalizing things 
that R doesn't know about.

If you want to be less conservative, then you could look at the source 
code:  currently R_RunExitFinalizers is the very first
part of the cleanup.  I don't know if we guarantee this though.

Duncan Murdoch
Is there any further documentation on what happens when an R session
shuts down and in which order?

/Henrik

 Duncan Murdoch

 Michael

 On Fri, Mar 11, 2011 at 10:19 AM, Jeffrey
 Ryan<jeffrey.ryan at lemnica.com>wrote:

 >    Take a look at reg.finalizer.  You'd have to create an object
 >    internally that would persist until R exits - and a related function
 >    to handle cleanup of course.
 >
 >    HTH
 >    Jeff
 >
 >    On Fri, Mar 11, 2011 at 12:08 PM, Michael Lawrence
 >    <lawrence.michael at gene.com>    wrote:
 >    >    Hi,
 >    >
 >    >    Is there any way that a package can listen for when R quits? The Qt
 >  stuff
 >    is
 >    >    hooking into platform-specific event loops and when those die
 >    unexpectedly
 >    >    (from the perspective of Qt), it aborts, causing an annoying error
 >    dialog.
 >    >    If we could catch when R is killed, we could cleanup, like we do
 >  with
 >    >    .onUnload.
 >    >
 >    >    Thanks,
 >    >    Michael
 >    >
 >    >           [[alternative HTML version deleted]]
 >    >
 >    >    ______________________________________________
 >    >    R-devel at r-project.org mailing list
 >    >    https://stat.ethz.ch/mailman/listinfo/r-devel
 >    >
 >
 >
 >
 >    --
 >    Jeffrey Ryan
 >    jeffrey.ryan at lemnica.com
 >
 >    www.lemnica.com
 >
         [[alternative HTML version deleted]]

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 Brian D. Ripley,                  ripley at stats.ox.ac.uk
 Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
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hook for when R quits

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