style question: returning multiple arguments - structure orlist

A little summer exercise: Can one write a list assignment function,
i.e. "list<-" so that

list(a,b,c) <- f()

would be equivalent to

r <- f()
a <- r[[1]]
b <- r[[2]]
c <- r[[3]]

Even better, do something useful with named list elements. (And what
are the odds of finding that this is really an exercise hidden
somewhere in a book by Venables and Ripley?)

I think you'll find that the first argument of an assignment function has
to exist already -- the function is passed the evaluated first argument.

This means it isn't quite true that
  a<-"foo<-"(a,value)
is the same as
  foo(a)<-value

eg

"foo<-"<-function(x,value){list(substitute(x),value)}
foo(a)<-4

Error: Object "a" not found

"foo<-"(a,1)

[[1]]
a

[[2]]
[1] 1

a<-1
foo(a)<-4
a

[[1]]
*tmp*

[[2]]
[1] 4


If this is correct, then you can't really write "list<-"

	-thomas

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