[Rd] setGeneric

Luke Tierney luke at stat.uiowa.edu
Tue Apr 1 17:22:43 MEST 2003

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.


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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