[Rd] external pointers

[Prof Brian Ripley]

On Mon, 12 Dec 2005, Byron Ellis wrote:

> There's also Luke's own site, in particular http://www.stat.uiowa.edu/ 
> ~luke/R/weakfinex.html

Hmm, that _is_ a link on the page I pointed you to, under its actual 
subject, weak references.

> On Dec 12, 2005, at 12:16 AM, Prof Brian Ripley wrote:
>
>> On Mon, 12 Dec 2005, Roger Bivand wrote:
>> 
>>>> Where would be best to read about externalptr? I'm having trouble
>>>> finding material in the manuals or the site-search.
>>>> 
>>>> And would I need to use all the .Call machinery and C headers and SEXP
>>>> etc in order to handle externalptr objects?
>>> 
>>> One package using externalptr is rgdal - Tim Keitt wrote the bindings to
>>> the external GDAL library for reading raster images to first return a
>>> pointer to a dataset (on disk) opened by GDAL, then to use the object to
>>> retrieve (parts of) the data. Most of the .Call/SEXP machinery is there
>>> (for the C++ case, GDAL is C++, so GDAL manages its own memory for its
>>> objects). The package also uses S4 classes, which may be overkill for your
>>> purposes.
>> 
>> RODBC is another, somewhat simpler, one.
>> 
>> There is documentation on developer.r-project.org, but my recollection is
>> that is was not up to date (and in particular not re finalizers).  On my
>> TODO list is to add end-user documentation to `Writing R Extensions'.

-- 
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