How to patch an S4 method in an R package?

Question

If you find a bug in a package, it's usually possible to patch the problem with fixInNamespace, e.g. fixInNamespace("mean.default", "base").

For S4 methods, I'm not sure how to do it though. The method I'm looking at is in the gWidgetstcltk package. You can see the source code with

getMethod(".svalue", c("gTabletcltk", "guiWidgetsToolkittcltk"))

I can't find the methods with fixInNamespace.

fixInNamespace(".svalue", "gWidgetstcltk")

Error in get(subx, envir = ns, inherits = FALSE) : 
  object '.svalue' not found

I thought setMethod might do the trick, but

setMethod(".svalue", c("gTabletcltk", "guiWidgetsToolkittcltk"),
  definition = function (obj, toolkit, index = NULL, drop = NULL, ...) 
  {
      widget = getWidget(obj)
      sel <- unlist(strsplit(tclvalue(tcl(widget, "selection")), 
          " "))
      if (length(sel) == 0) {
          return(NA)
      }
      theChildren <- .allChildren(widget)
      indices <- sapply(sel, function(i) match(i, theChildren))
      inds <- which(visible(obj))[indices]
      if (!is.null(index) && index == TRUE) {
          return(inds)
      }
      if (missing(drop) || is.null(drop)) 
          drop = TRUE
      chosencol <- tag(obj, "chosencol")
      if (drop) 
          return(obj[inds, chosencol, drop = drop])
      else return(obj[inds, ])
  },
  where = "package:gWidgetstcltk"  
)

Error in setMethod(".svalue", c("gTabletcltk", "guiWidgetsToolkittcltk"),  : 
  the environment "gWidgetstcltk" is locked; cannot assign methods for function ".svalue"

Any ideas?

Answer 1

How about the old-school way of getting the source, applying the change and rebuilding?