R help - Mar 2016 - How to make a function aware of its own call arguments

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

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
>
>______________________________________________
>R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>https://stat.ethz.ch/mailman/listinfo/r-help
>PLEASE do read the posting guide
>http://www.R-project.org/posting-guide.html
>and provide commented, minimal, self-contained, reproducible code.
	[[alternative HTML version deleted]]

Hi,

Thanks for your suggestion.

missing(x) works only if x is not altered within the function, which is 
not the case in my actual function (which is more complex than the 
example function I send in my previous post).

Are you aware of any function what would query the original function 
call arguments no matter what happens in the function?

Sebastien

On 3/24/2016 8:47 AM, Jeff Newmiller wrote:
> 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
>
>    
------------------------------------------------------------------------
>
>     R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>     https://stat.ethz.ch/mailman/listinfo/r-help
>     PLEASE d
>       o read
>     the posting guidehttp://www.R-project.org/posting-guide.html
>     and provide commented, minimal, self-contained, reproducible code.
>
-- Sebastien Bihorel Associate Director, Pharmacometrics Buffalo Office: 
+1-716-633-3463 ext. 323 | Website <http://www.cognigencorp.com> 
<http://www.simulations-plus.com/Default.aspx>