[R-SIG-Mac] Example in body() help page, unexpected warning

[Prof Brian Ripley]

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?

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
>
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> R-SIG-Mac at stat.math.ethz.ch
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-- 
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