[Rd] setGeneric

Luke Tierney luke at stat.uiowa.edu
Tue Apr 1 21:45:16 MEST 2003

On Tue, 1 Apr 2003, Luke Tierney wrote:

> On Tue, 1 Apr 2003, John Chambers wrote:
> > I think this is a consequence of the extra context added to make methods
> > work right with R lexical scoping, namespaces, etc.  Or a subtlety in
> > R's definition of missing()?
> > 
> > The problem is that somehow the default expression for argument `ncol'
> > makes that argument appear NOT to be missing.  But an attempt to
> > evaluate it fails because the local variable `n' hasn't been defined
> > yet.
> > 
> > The following debugging snippets, using trace on the method for
> > "numeric", show what's happening.  But as to why, we need some expert
> > help! (Luke?)
> We need a bit more info transferred across from the generic and we
> need to reset the environments of the promises for missing arguments.
> I'll look into it.

A workaround should be in place in R-devel now.


Luke Tierney
University of Iowa                  Phone:             319-335-3386
Department of Statistics and        Fax:               319-335-3017
   Actuarial Science
241 Schaeffer Hall                  email:      luke at stat.uiowa.edu
Iowa City, IA 52242                 WWW:  http://www.stat.uiowa.edu

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