From ripley at stats.ox.ac.uk  Fri Feb 27 19:19:00 2004
From: ripley at stats.ox.ac.uk (Prof Brian Ripley)
Date: Fri Feb 27 19:21:39 2004
Subject: [Rd] package 'stats' needs import directive for 1.9.0?
In-Reply-To: <403F7D82.4040100@bank-banque-canada.ca>
Message-ID: <Pine.LNX.4.44.0402271815310.16912-100000@gannet.stats>

On Fri, 27 Feb 2004, Paul Gilbert wrote:

[...]

> >>This  would conflict (and override?) the 
> >>S3 generic in base, which I don't think is allowed in 1.9.0. Until 
> >>recently I have been overriding the start function in base (and some 
> >>others) with my own S3 generic, and have just gone through a rather 
> >>lengthy exercise to  rename these functions and some objects and other 
> >>methods so that things do work in 1.9.0. (They do also work in 1.8.1.)
> >>
> >>Will S3 and S4 generics for start co-exist? What happens to all the S3 
> >>methods for start if the S4 generic is loaded? Won't this break a lot of 
> >>code other than mine?
> >
> >There should be no problem with an S4 generic, as it calls the actual
> >existing S3 generic as its default S4 method.  It's done for plot(), for
> >example.  What will not work is having a different S3 generic of the same
> >name in a different namespace (including in the residual non-namespace).
> >
> Ok. Will two S4 generics co-exist? Perhaps the S4 generics should be 
> defined in base just in case someone else wants to to have an S4 start 
> method too?  (This would apply to a lot of other S3 generics in addition 
> to start.)

Essentially, yes they can coexist and there is no need to predefine S4
generics just in case someone wants to write methods.  As I said, cases
like plot() and summary() get used in lots of places (although plot() is
AFAIR defined in methods).

-- 
Brian D. Ripley,                  ripley@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] package 'stats' needs import directive for 1.9.0?
Prof Brian Ripley