[R-pkg-devel] Creating Accessor Methods

[Thomas Petzoldt]

On 10.03.2016 16:48, Daniel Nüst wrote:
> Hi Glenn!
>
> On 10/03/16 15:05, Glenn Schultz wrote:
>> I have a package with to S4 classes (MBSCashFlow, REMICCashFlow and
>> BondCashFlow) all of which contain the slot Duration.  I would like
>> have an accessor Duration that would work on multiple signatures.  Is
>> this possible?  I have checked my books, help, BioConductor tutorials
>> and it appears that this is not possible.  Has anyone ever run into
>> this situation?
>
> I actually use a similar mechanism to extract values from different S4
> classes in my package, and it works quite well. So if I understand you
> right, the following code might help you to get closer to want you want:
>
> https://github.com/52North/sos4R/blob/master/R/SOS-methods-accessor.R
>
> I created methods for different signatures, see for example
> "sosObservedProperties".

Yes, that's straightforward. But I still wonder if it is at all possible 
to use not only different *signatures*, but also different argument 
*names* in S4, e.g.:

foo(formula, data, ...)

foo(data, grouping, ...)


Now I'm using a combination of S3 and S4 in my package for this purpose, 
and for some other quirks.

Thomas


-- 
Dr. Thomas Petzoldt
Technische Universitaet Dresden
Faculty of Environmental Sciences
Institute of Hydrobiology
01062 Dresden, Germany

E-Mail: thomas.petzoldt at tu-dresden.de
http://tu-dresden.de/Members/thomas.petzoldt