From h.wickham at gmail.com  Mon Feb 18 19:59:44 2013
From: h.wickham at gmail.com (Hadley Wickham)
Date: Mon, 18 Feb 2013 12:59:44 -0600
Subject: [Rd] quote() vs quote(expr=)
In-Reply-To: <alpine.LFD.2.03.1302181238210.10691@uiowa.edu>
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	<alpine.LFD.2.03.1302181227030.10691@uiowa.edu>
	<CABdHhvFs3voJjhQ7oCMMxXSTkDvAQje_Nr2dnkWJsMwJf9z0qA@mail.gmail.com>
	<alpine.LFD.2.03.1302181238210.10691@uiowa.edu>
Message-ID: <CABdHhvHcAG77QVXu0o5x1AHORgv_fKGggFYPU4njk+jFkGcA-Q@mail.gmail.com>

Ok, that's what I thought.  Thanks!
Hadley

On Mon, Feb 18, 2013 at 12:43 PM,  <luke-tierney at uiowa.edu> wrote:
> Of course not. What I hope can happpen is that we can reduce the
> degree to which internal implementation quirks leak out into the user
> level. The fact that there is an internal "missing token" (that
> happens to be used for a couple of different things) is a quirk; if
> you look at the code I use you can see why it is a quirk. Cleaning
> this up will help computing on the language (at least that is the
> hope).
>
>
> luke
>
> On Mon, 18 Feb 2013, Hadley Wickham wrote:
>
>> In general, should we expect that the ability to compute on the
>> language within R will decrease over time? Otherwise, I presume if you
>> do change the behaviour of missing then you'll still provide some way
>> to create/call functions with missing arguments.
>>
>> Hadley
>>
>> On Mon, Feb 18, 2013 at 12:31 PM,  <luke-tierney at uiowa.edu> wrote:
>>>
>>> I wouldn't count on any way of capturing this thing being reliable in
>>> the long term.  As I recall what I do in codetools and the compiler is
>>> use features of missing() to test for it, but try to abstract those
>>> uses into one or two places only so I can easily change them if
>>> missing()'s behavior changes. Basically this internal thing
>>> _shouldn't_ be visible at R level, and if we ever figure out how to
>>> make that happen it will.
>>>
>>> Best,
>>>
>>> luke
>>>
>>>
>>> On Mon, 18 Feb 2013, Hadley Wickham wrote:
>>>
>>>> Hi all,
>>>>
>>>> I think there's a small buglet in quote:
>>>>
>>>> str(quote())
>>>> # Error in quote() : 0 arguments passed to 'quote' which requires 1
>>>> str(quote(expr = ))
>>>> # symbol
>>>>
>>>> I bring this up because this seems like the most natural way of
>>>> capturing the "missing" symbol with pure R code, compared to
>>>> substitute() or bquote() or formals(plot)$x
>>>>
>>>> Hadley
>>>>
>>>>
>>>
>>> --
>>> Luke Tierney
>>> Chair, Statistics and Actuarial Science
>>> Ralph E. Wareham Professor of Mathematical Sciences
>>> University of Iowa                  Phone:             319-335-3386
>>> Department of Statistics and        Fax:               319-335-3017
>>>    Actuarial Science
>>> 241 Schaeffer Hall                  email:   luke-tierney at uiowa.edu
>>> Iowa City, IA 52242                 WWW:  http://www.stat.uiowa.edu
>>
>>
>>
>>
>>
>
> --
> Luke Tierney
> Chair, Statistics and Actuarial Science
> Ralph E. Wareham Professor of Mathematical Sciences
> University of Iowa                  Phone:             319-335-3386
> Department of Statistics and        Fax:               319-335-3017
>    Actuarial Science
> 241 Schaeffer Hall                  email:   luke-tierney at uiowa.edu
> Iowa City, IA 52242                 WWW:  http://www.stat.uiowa.edu



-- 
Chief Scientist, RStudio
http://had.co.nz/



[Rd] quote() vs quote(expr=)
Hadley Wickham