D() returns an argument of type call in R code example

Example 1: calculated defualt values in R function parameters

fun <- function(x,levels=levels(x)){
    blah blah blah
}

Example 2: calculated defualt values in R function parameters

fun <- function(x,y=getOption('fun.y','initialDefault')){# or getOption('pkg.fun.y',defaultValue)
    blah blah blah
}