From r.hankin at noc.soton.ac.uk  Fri Sep  9 13:09:58 2005
From: r.hankin at noc.soton.ac.uk (Robin Hankin)
Date: Fri, 9 Sep 2005 12:09:58 +0100
Subject: [Rd] two almost identical packages: best practice
Message-ID: <8B2D83C0-69CF-48DA-BF80-98ECC67AF55B@soc.soton.ac.uk>

Hi

I have written a whole bunch of methods for objects of class "octonion".

[
an octonion is a single column of an eight-row matrix.  Octonions have
their own multiplication rules and are a generalization of quaternions,
which are columns of a four-row matrix.
]

So far I've done about a dozen generic functions such as seq.octonion(),
rep.octonion(), [<-.octonion(),  and so on and so on.

Very nearly all  of these functions are applicable to objects of  
class "quaternion".
So, for example, I have a generic function Im.octonion():

R> Im.octonion
function (x)
{
     Re(x) <- 0
     return(x)
}

The definition of Im.quaternion() is exactly the same.
Sometimes the return value is an octonion:

  Conj.octonion
function (x)
{
     x <- as.matrix(x)
     x[-1, ] <- -x[-1, ]
     return(as.octonion(x))
}

So the last line of Conj.quaternion() would be "return(as.quaternion 
(x))"
but would be otherwise identical.
A similar story holds for each of maybe twenty generic functions.
Nearly all the Rd files are similarly identical:  the word "octonion"
replaces the word  "octonion".  I suppose "A" changes to "An" as well.

There is a small number of functions and datasets that are specific  
to octonions.

What is Best Practice in this situation?  I don't want to edit two  
separate
packages in tandem.   Is there a mechanism for doing what I want
in the context of a bundle?




--
Robin Hankin
Uncertainty Analyst
National Oceanography Centre, Southampton
European Way, Southampton SO14 3ZH, UK
  tel  023-8059-7743



[Rd] two almost identical packages: best practice
Robin Hankin