From ripley at stats.ox.ac.uk  Fri Sep 16 10:06:33 2005
From: ripley at stats.ox.ac.uk (Prof Brian Ripley)
Date: Fri, 16 Sep 2005 09:06:33 +0100 (BST)
Subject: [Rd] loadings()   generic in R alpha
In-Reply-To: <4329B504.3020209@bank-banque-canada.ca>
References: <4329B504.3020209@bank-banque-canada.ca>
Message-ID: <Pine.LNX.4.61.0509160855171.31294@gannet.stats>

On Thu, 15 Sep 2005, Paul Gilbert wrote (in two separate messages)

> Could loadings()  in R-2.2.0  please be made generic?

> Could acf()  in R-2.2.0  please be made generic?

I think it is too late in the process for this (and especially for acf). 
In particular, it could have knock-on consequences for packages and 
recommended packages are scheduled to be all fixed in stone by next Weds.

To consider making such functions generic we would need

- a case
- discussion of what the arguments of the generic should be and what is
   to be specified about the return value.

Perhaps you could raise these again with specific proposals early in the 
developement cycle for 2.3.0.

(We have been a little too casual about speciying what generic functions 
should return in the past, and have got bitten as a result.  For example, 
can it be assumed that loadings() returns a matrix?)

-- 
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



[Rd] loadings() generic in R alpha
Prof Brian Ripley