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

[luke-tierney at uiowa.edu]

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
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