R help - Apr 1997 - R-beta: An all.names function

I could not find the all.names function in R so I created the
enclosed.  Comments, criticisms, or changes to a one-liner by creating
nested anonymous functions are welcome.  I'll try to work out a
corresponding all.vars function.

### $Id: allFns.R,v 1.2 1997/04/28 13:08:21 bates Exp $
### Some replacement functions that are missing in R

### Determine all the names (symbols) occuring in an object.
### This is probably grossly inefficient.
all.names <-
  function (x) 
{
  if (mode(x) == "symbol") 
    return(as.character(x))
  if (length(x) == 0) 
    return(NULL)
  if (is.recursive(x)) 
    return(unlist(lapply(as.list(x), all.names)))
  character(0)
}   

### Local variables:
### mode: R
### End:

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Doug,

your 'all.names' function
	[wow, I didn't even know it in S..]
seems to have been written with S in your mind;
you are exactly demonstrating some of the 'fine' differences between  R
& S
>1> all.names <- function (x) 
>2> {
>3>   if (mode(x) == "symbol")  return(as.character(x))
>4>   if (length(x) == 0)       return(NULL)
>5>   if (is.recursive(x))      return(unlist(lapply(as.list(x),
all.names)))
>6>   character(0)
>7> }   
1) length(x) is not always defined in R; e.g. it is NOT for functions.
   --> Delete line 4  

2) functions  are NOT lists and cannot be coerced to,
   which makes line 5 fail for function objects.

As a matter of fact, I once was also a bit interested in this.
At that time, 'args' did not yet exist, and I wanted to abuse
'as.list' for
functions.
I was told that this is 'bad'
	(functions have nothing to do with lists;
	 in R, functions can have a defining environment going with them...)
and 'args' is now provided which helps my most immediate need.


In short: I don't think  you can define an  all.names(.) function which
	  works with functions arguments, in the current version of R.




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