For a package providing 'virtual' data.frames backed by MonetDB database tables, we want to make some functions generic, to implement versions that work on single or multiple database columns. My approach was sd <- function(x, na.rm=TRUE,...) UseMethod("sd") sd.default<- base::sd I've done that before to make dotchart() generic in the 'survey' package. With dotchart() (and even sd()) there still doesn't seem to be a problem (based on the CRAN check results), but with var() we get a note Found .Internal call in the following function: ‘var.default’ with calls to .Internal functions ‘cov’ because base::var contains calls to .Internal. These seems harmless to me -- the package is only calling .Internal() through base functions in usual way. We could use var.default<-function(x, y=NULL, na.rm=TRUE, ...) base::var(x,y,na.rm,...) but it seems that could have different lazy-evaluation behaviour. -thomas -- Thomas Lumley Professor of Biostatistics University of Auckland [[alternative HTML version deleted]]