Example in body() help page, unexpected warning

On Dec 27, 2009, at 2:07 AM, Prof Brian Ripley wrote:

Hmm, when I run example(body) I get

body> body(f) <- as.call(c(as.name("{"), e))

with no backslash.  And text help and the refman also have no backslash.

So, how are you doing this?  Cut-and-paste from HTML help?

Yes; that was how I entered it, but just now I entered this line from the 
keyboard and got the same result:

body(f) <- as.call(c(as.name("\{"), e))

Warning messages:
1: '\{' is an unrecognized escape in a character string
2: unrecognized escape removed from "\{"

--

I suspect this is yet another rendering problem with HTML help: I've fixed 
quite a few since 2.10.1 was released.

On Sat, 26 Dec 2009, David Winsemius wrote:

I am getting a warning when using the example s on the help page for body:

f <- function(x) x^5
body(f) <- quote(5^x)
## or equivalently  body(f) <- expression(5^x)
f(3) # = 125

[1] 125

body(f)

5^x

## creating a multi-expression body
e <- expression(y <- x^2, return(y)) # or a list
body(f) <- as.call(c(as.name("\{"), e))

Warning messages:
1: '\{' is an unrecognized escape in a character string
2: unrecognized escape removed from "\{"

f

function (x)
{
y <- x^2
return(y)
}

f(8)

[1] 64

The text of the Details section says that:
"The bodies of all but the simplest are braced expressions, that is calls 
to {: see the ?Examples? section for how to create such a call."

So I am puzzled that "\{" is being removed.

That is *not* what the message says: it says the backslash is being 
removed.

sessionInfo()

R version 2.10.1 RC (2009-12-09 r50695)
x86_64-apple-darwin9.8.0

Please update to a released version.

locale:
[1] en_US.UTF-8/en_US.UTF-8/C/C/en_US.UTF-8/en_US.UTF-8

attached base packages:
[1] grid      splines   stats     graphics  grDevices utils     datasets 
methods   base

other attached packages:
[1] gplots_2.7.4    caTools_1.10    bitops_1.0-4.1  gdata_2.6.1 
gtools_2.6.1
[6] hexbin_1.20.0   seqinr_2.0-7    kernlab_0.9-9   IDPmisc_1.1.06 
lattice_0.17-26
[11] Design_2.3-0    Hmisc_3.7-0     survival_2.35-7

loaded via a namespace (and not attached):
[1] cluster_1.12.1 tools_2.10.1

-- 

David Winsemius, MD
Heritage Laboratories
West Hartford, CT

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

David Winsemius, MD
Heritage Laboratories
West Hartford, CT