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

[David Winsemius]

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
>>
>> _______________________________________________
>> R-SIG-Mac mailing list
>> R-SIG-Mac at stat.math.ethz.ch
>> https://stat.ethz.ch/mailman/listinfo/r-sig-mac
>
> -- 
> 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