Capturing the expression representing the body of a function

Hi all,

What's the preferred way of capturing the expression representing the
contents of a function?

* body(write.csv) gives me a braced expression
* body(write.csv)[-1] gives me a mangled call
* as.list(body(write.csv)[-1]) gives me a list of calls
* as.expression(as.list(body(write.csv)[-1])) is what I want but seems
like too much work

Any suggestions?

The body of a function isn't an expression, it's a language object.  A 
language object is represented internally as a pairlist, while an 
expression is represented as a generic vector, i.e. the thing that 
list() gives.

Your 1st try gives you the language object.

The other ones only work when the body consists of a call to `{`, as the 
body of most complex functions does, but not for simple ones like

f <- function(x) 2*x

So I would say your question should be:  "What's the best way to 
construct an expression vector s.t. evaluating its elements in order is 
like evaluating the body of a function?"

And the answer to that is something like

body2expr <- function(f) {
   body <- body(f)
   if (typeof(body) == "language" && identical(body[[1]], quote(`{`))) 
as.expression(as.list(body[-1]))
   else as.expression(body)
}

Duncan Murdoch