From hadley at rice.edu  Sat Oct  2 16:40:33 2010
From: hadley at rice.edu (Hadley Wickham)
Date: Sat, 2 Oct 2010 09:40:33 -0500
Subject: [Rd] Eval and the enclos argument
In-Reply-To: <4CA7311A.1000304@gmail.com>
References: <AANLkTinQ8fXByLEkJqCFOr9i4Q5KNSnf2cfAD0vBJy-6@mail.gmail.com>
	<4CA7311A.1000304@gmail.com>
Message-ID: <AANLkTinUc0-XXNa5+MxTa_GrXquywKv9sPkMGZa8LTHx@mail.gmail.com>

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/



[Rd] Eval and the enclos argument
Hadley Wickham