Namespaces, coercion and setAs

On Fri, 26 Nov 2004, roger koenker wrote:

I'm trying to resolve a small problem that has arisen from 
introducing a
NAMESPACE for the package SparseM.  Prior to the namespace I had a 
class
"matrix.diag.csr" that consisted of diagonal sparse matrices.  It was
defined to have the same attributes as the matrix.csr class and setAs
was used to define how to coerce integers and vectors into this form:

setClass("matrix.diag.csr","matrix.csr")

setAs("numeric","matrix.diag.csr",function(from){
         if(length(from)==1){
                 n <- as.integer(from)
                 if(n>0) from  <-  rep(1,n)
                 else stop("Sparse identity matrices must have 
positive,
integer dimension")
                 }
         else n <- length(from)
         return(new("matrix.diag.csr", ra = from ,ja = 
as.integer(1:n),
                 ia = as.integer(1:(n+1)), dimension =
as.integer(c(n,n))))
         })

This seemed to be fine.   I could do,

	A  <- as(5,"matrix.diag.csr")

and A would be a 5x5 identity matrix in sparse form.  But 
post-namespace
I get:

A <- as(5,"matrix.diag.csr") Error in as(5, "matrix.diag.csr") : No

method or default for coercing "numeric" to "matrix.diag.csr"

so apparently using exportClass(matrix.diag.csr)  isn't sufficient for
coerce to know what to do. Using findClass("matrix.diag.csr") 
indicates
that the class is recognized to be from SparseM, so my question is:  
is
there some mechanism that I'm missing in the NAMESPACE scheme that 
would
enable my old setAs() directive to work, or is there some other
suggestion on how to proceed?

I'm far from sure about this, but is "coerce" one of the exported 
methods?
I'm having the same difficulty in retrofitting a NAMESPACE to the
forthcoming sp package of spatial classes, for S4 classes.

I see from src/library/methods/NAMESPACE that as and coerce are 
exported
from there - should a package with a NAMESPACE and S4 classes do

import(methods) ?

Roger

url:	www.econ.uiuc.edu/~roger        	Roger Koenker
email	rkoenker@uiuc.edu			Department of Economics
vox: 	217-333-4558				University of Illinois
fax:   	217-244-6678				Champaign, IL 61820

-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School 
of
Economics and Business Administration, Breiviksveien 40, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 93 93
e-mail: Roger.Bivand@nhh.no