[R] suggestion on method dispatch

[Wincent]

Dear all, I have define a function  and its methods as follows:

######## beginning of code
fn <- function(x,...){
UseMethod("fn")
}

fn.foo1 <- function(x, commonA=1, ...){
print("fn.foo1 is called.")
}

fn.foo2 <- function(x, uniqueFoo2, common=1, ...){
## uniqueFoo2 is a unique argument in fn.foo2
x <- uniqueFoo2; class(x) <- "foo1"
## use uniqueFoo2 to generate a object of class foo1
dots <- list(...)
do.call(fn.foo1, c(list(x=x,common=common),dots)
## pass x, commonA and other arguments from ... to fn.foo1
}

y <-  "y"; class(y) <- "foo2"
fn(x=y, "unique argument")

######## end of code

They works as expected. I call fn.foo1 because I don't want to
duplicate the same piece of code.
Yet, I wonder if here is any official way to do the same thing without
directly call fn.foo1 via do.call.
To directly call a method is not a good coding style, right?

Thanks very much for your suggestion in advance.

-- 
Wincent Rong-gui HUANG
Doctoral Candidate
Dept of Public and Social Administration
City University of Hong Kong
http://asrr.r-forge.r-project.org/rghuang.html