[BioC] limma MArrayLM subclass question

[Cyrus Harmon]

Dear bioc-devel,

I'd like to subclass MArrayLM (I think), but I'm having some trouble:

setClass("myMArrayLM", "MArrayLM")
assign("[.myMArrayLM", function(object, i, j, ...)  
{ "[.MArrayLM"(object, i, j, ...) });

and then I thought I could just do this (given def, an MArrayLM object)

as("myArrayLM", def);

But when I try that I get the following error message:

 > as("myArrayLM", def);
Error in methodsPackageMetaName("C", name) :
     'The name of the object (e.g,. a class or generic function) to  
find in the meta-data' must be a single string (got an object of  
class "matrix")
In addition: Warning message:
the condition has length > 1 and only the first element will be used  
in: if (is.na(i)) {
 >

Has anyone successfully subclassed MArrayLM? Is this something I just  
shouldn't be doing? It seems natural to want to store additional data  
in an MArrayLM and get the proper subsetting behavior, piggybacking  
on MArrayLM's existing behavior.

Also, is this the right place for limma questions? It doesn't have  
its own mailing list yet, does it?

Thanks,

Cyrus Harmon