[R] setGeneric / standardGeneric when args are not "literals"

[Vadim Ogranovich]

Hi,
 
This works

> setGeneric("clear", function(obj) standardGeneric("clear"))
[1] "clear"
 
but this doesn't. Why?

> funName <- "clear"
> setGeneric(funName, function(obj) standardGeneric(funName))
Error in .recursiveCallTest(body, fname) : 
 (converted from warning) The body of the generic function for "clear"
calls standardGeneric to dispatch on a different name ("funName")!
 

This is R-1.8.1 on RH-7.3
 
 
I came across it while trying to write a helper function that would
"safely" create generics when a function with such a name already
exists. Here is what I adapted from S4Objects but it doesn't work
becuase of the above-mentioned problem. Any suggestion how to make it
work, please?
 
setMakeGenericMethod <- function(methodName, className, fun) {
  # sets a method and creates the generics if neccessary
  if (!isGeneric(methodName)) {
    if (is.function(methodName)) {
      fun.default <- get(methodName)
    }
    else {
      fun.default <- function(object) standardGeneric(methodName)
    }
  }
 
  setGeneric(methodName, fun.default)
 
  setMethod(methodName, className, fun)
}


Thanks,
Vadim