[Rd] Eval and the enclos argument

[Hadley Wickham]

On Sat, Oct 2, 2010 at 8:18 AM, Duncan Murdoch <murdoch.duncan at gmail.com> wrote:
> On 02/10/2010 7:57 AM, Hadley Wickham wrote:
>>
>> Hi all,
>>
>> I'm trying to understand the default value of the enclos argument of eval:
>>
>>  enclos = if(is.list(envir) || is.pairlist(envir)) parent.frame()
>> else baseenv()
>>
>> Why isn't it just
>>
>>  enclos = parent.frame()
>>
>> given that enclos is only meaningful (given my reading of the
>> documentation) when envir is not an environment already.
>>
>> Hadley
>>
>
>
> I think that handles the case of envir=NULL.

So that makes eval(expr, NULL) equivalent to eval(expr, baseenv()), right?

Hadley


-- 
Assistant Professor / Dobelman Family Junior Chair
Department of Statistics / Rice University
http://had.co.nz/