[Rd] Capturing the complete unevaluated expression corresponding to function (body + formals)

Hadley Wickham hadley at rice.edu
Wed May 4 15:30:08 CEST 2011

On Wed, May 4, 2011 at 8:07 AM, Duncan Murdoch <murdoch.duncan at gmail.com> wrote:
> On 04/05/2011 8:38 AM, Hadley Wickham wrote:
>> Hi all,
>> Is there any way to capture the complete unevaluated expression
>> corresponding to a function?  I want the equivalent of
>> x<- quote(function(x) x = 3)
>> But captured after the function is created.  Body and formals each
>> captures a part, but is there a built in way to get the whole thing?
> Internally, "function" is a function that produces a closure object.  After
> you call it and the function is created, the inputs are gone, all you have
> is the result.  But you can reconstruct it as you did below, because
> "function" basically just glues the parts together (and adds an environment
> as well).

Ok, I was getting confused because it looks like deparse and print(f,
useSource = F) can print the whole thing. But looking at the source, I
see that they reconstruct the function from the formals and the body


Assistant Professor / Dobelman Family Junior Chair
Department of Statistics / Rice University

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