R devel - Mar 2009 - S4 generic masking S3 generic when using namespace

Hi,

I have two example packages, test1 and test2, where the only code in 
them is:

setGeneric("predict", function(object, ...)
standardGeneric("predict"))

(get them from http://www.cs.mu.oz.au/~gabraham/test1.tar and 
http://www.cs.mu.oz.au/~gabraham/test2.tar)

The difference between them is that first does not have a namespace, and 
loads fine. The second has a namespace but generates a warning:
 > library(test2)

Attaching package: 'test2'


	The following object(s) are masked from package:stats :

	 predict



Is this an intended behaviour? If I ignore this masking warning, do I 
risk unintended consequences later down the track?

Thanks,
Gad



 > sessionInfo()
R version 2.8.1 (2008-12-22)
i386-apple-darwin8.11.1

locale:
en_AU.UTF-8/en_AU.UTF-8/C/C/en_AU.UTF-8/en_AU.UTF-8

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

other attached packages:
[1] test2_0.1


-- 
Gad Abraham
MEng Student, Dept. CSSE and NICTA
The University of Melbourne
Parkville 3010, Victoria, Australia
email: gabraham at csse.unimelb.edu.au
web: http://www.csse.unimelb.edu.au/~gabraham

Try using setGeneric("predict") without further arguments, this should
work as it will take the existing 'predict' definition and convert it
into S4 generic. This works nicely for me for all plot, print etc
methods

* R   
*** R 2.9.0 (svn -r 47821) [/share/research/R-devel/20090203/lib64/R]
***
> setGeneric("predict")
[1] "predict"
> predict
standardGeneric for "predict" defined from package "stats"

function (object, ...) 
standardGeneric("predict")
<environment: 0xe24b080>
Methods may be defined for arguments: object
Use  showMethods("predict")  for currently available ones.

Dr Oleg Sklyar
Research Technologist
AHL / Man Investments Ltd
+44 (0)20 7144 3107
osklyar at maninvestments.com 
> -----Original Message-----
> From: r-devel-bounces at r-project.org 
> [mailto:r-devel-bounces at r-project.org] On Behalf Of Gad Abraham
> Sent: 10 March 2009 10:02
> To: R-devel at r-project.org
> Subject: [Rd] S4 generic masking S3 generic when using namespace
> 
> Hi,
> 
> I have two example packages, test1 and test2, where the only code in 
> them is:
> 
> setGeneric("predict", function(object, ...) 
> standardGeneric("predict"))
> 
> (get them from http://www.cs.mu.oz.au/~gabraham/test1.tar and 
> http://www.cs.mu.oz.au/~gabraham/test2.tar)
> 
> The difference between them is that first does not have a 
> namespace, and 
> loads fine. The second has a namespace but generates a warning:
>  > library(test2)
> 
> Attaching package: 'test2'
> 
> 
> 	The following object(s) are masked from package:stats :
> 
> 	 predict
> 
> 
> 
> Is this an intended behaviour? If I ignore this masking warning, do I 
> risk unintended consequences later down the track?
> 
> Thanks,
> Gad
> 
> 
> 
>  > sessionInfo()
> R version 2.8.1 (2008-12-22)
> i386-apple-darwin8.11.1
> 
> locale:
> en_AU.UTF-8/en_AU.UTF-8/C/C/en_AU.UTF-8/en_AU.UTF-8
> 
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  methods   base
> 
> other attached packages:
> [1] test2_0.1
> 
> 
> -- 
> Gad Abraham
> MEng Student, Dept. CSSE and NICTA
> The University of Melbourne
> Parkville 3010, Victoria, Australia
> email: gabraham at csse.unimelb.edu.au
> web: http://www.csse.unimelb.edu.au/~gabraham
> 
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
> 
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