standardization of slot access

Thank you all for your comments, which confirm the feeling I had that
'slot' is only needed in the rare occasions Roger mentioned.  Although
'slot' is an accessor function, it seems it's not quite analogous to
functions or methods for accessing components of objects.

I find that slot() is useful in explaining to users what is going on. I 
also find that used inside s/lapply that say function(x) slot(x, "y") is a 
natural way to access contents of lists of objects. So I wouldn't conclude 
that it is only rarely used, and would recommend its use in explaining to 
students/users what is going on in new-style objects.

Roger

Cheers,

Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand at nhh.no