How to make a function aware of its own call arguments

Don't provide a default value for c in the parameter list. Then you 
can use the missing() function to make decisions, including whether to 
generate a default value for c or not.
-- 
Sent from my phone. Please excuse my brevity.

On March 24, 2016 5:11:43 AM PDT, sbihorel 
<Sebastien.Bihorel at cognigencorp.com> wrote:

    Hi,

    Please consider the following functions:

    myf1 <- function(x,fun){
        if (is.null(fun)){
          x
        } else {
          do.call(fun, list(x))
        }
    }

    myf2 <- function(a=1, b=2, fun=NULL, c=myfun1(b,fun)){

        if (myf1(b,fun)>0 & <c was not provided in function call>){
          c <- b
        }
        print(list(a,b,c))
    }

    myf2(a=2,b=3,fun=exp)
    myf2(a=2,b=3,fun=exp,c=4)

    I need to replace "<c was not provided in function call>" by some code
    that would make myf2 aware of it own calls and of the fact that the c
    argument was provided or not in the function calls.

    Thanks for your help

    Sebastien

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