>>>>> Martin Maechler <maech...@stat.math.ethz.ch>
>>>>> on Fri, 9 Jan 2015 14:00:38 +0100 writes:
>>>>> Michael Lawrence <lawrence.mich...@gene.com>
>>>>> on Thu, 8 Jan 2015 14:02:26 -0800 writes:
>> On Thu, Jan 8, 2015 at 11:57 AM, <luke-tier...@uiowa.edu> wrote:
>>> On Thu, 8 Jan 2015, Michael Lawrence wrote:
>>>
>>> If we do add an argument to get(), then it should be named consistently
>>>> with the ifnotfound argument of mget().
You are right... I forgot to say so earlier in the thread.
The definition now is
get0 <- function (x, envir = pos.to.env(-1L), mode = "any", inherits = TRUE,
ifnotfound = NULL)
.Internal(get0(x, envir, mode, inherits, ifnotfound))
>>>> As mentioned, the possibility of a
>>>> NULL value is problematic. One solution is a sentinel value that
indicates
>>>> an unbound value (like R_UnboundValue).
>>>>
>>>
>>> A null default is fine -- it's a default; if it isn't right for a
>>> particular case you can provide something else.
>>>
[..................]
>>> Adding getIfExists, or .get, or get0, or whatever seems fine. Adding
>>> an argument to get() with missing giving current behavior may be OK
>>> too. Rewriting exists and get as .Primitives may be sufficient though.
> Thank you, Luke. Given that, Duncan's and the other inputs,
> I think we should go for a new function -- .Internal() for now.
> To Pete's point about arguments, I did drop 'frame' on purpose
> and indeed we could try to do away with 'where/pos' as well and
> have the environment only specified by 'envir'.
> Name: I like get0() for its brevity and prefer it to .get().
> Let me expose my current implementation on R-devel ... and start
> using it in the 'methods' package so we (Pete H. :-) can start
> measuring its impact.
I have now committed get0() to R-devel (svn rev 67386)
which is already using it in quite a few places:
in 'base', notably in base/R/namespace.R where it may speedup, also
in 'methods' in quite a few places also in the hope of some S4
speedup.
{{Now I feel having deserved some weekend break ...}}
Martin
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