Re: [Rd] "\088" is legal syntax?

From: Duncan Murdoch <murdoch.duncan_at_gmail.com>
Date: Thu, 01 Sep 2011 20:55:38 -0400

On 11-09-01 8:47 PM, William Dunlap wrote:
> The CRAN package svMisc misuses it, using "\8" instead of "\10" or "\b":
> ./svMisc/R/progress.R: backspaces<- paste(rep("\8", l3), collapse = "")
>
> I noticed it when S+ emitted a warning when parsing that file:
> > p<- parse("svMisc/R/progress.R")
> Warning messages:
> The initial backslash is ignored in \8 -- not a recognized escape sequence.
> Use \\ to make a backslash in: parse("svMisc/R/progress.R")
> (S+ parses the "\8" as "8", as the warning obliquly implies.)
>
> I grepped through other CRAN sources for "\\0*8" and also found

I don't have the CRAN sources installed here so I can't check myself, but grepping for \\[0-7]*8 might find other instances. The parser would accept an 8 in any position.

Duncan

> ./mvbutils/R/mvbutils.R: rep.percent<- '\008'
> S+ emits no warning for that but parses it as "", because it
> considers the octal escape to stop at the first non-octal digit.

> Bill Dunlap
> Spotfire, TIBCO Software
> wdunlap tibco.com
>
>> -----Original Message-----
>> From: Duncan Murdoch [mailto:murdoch.duncan_at_gmail.com]
>> Sent: Thursday, September 01, 2011 5:30 PM
>> To: William Dunlap
>> Cc: r-devel_at_r-project.org
>> Subject: Re: [Rd] "\088" is legal syntax?
>>
>> On 11-09-01 5:43 PM, William Dunlap wrote:
>>> Is it intentional that the digit 8 is allowed
>>> in octal escape sequences in character literals?
>>>
>>> > "\110" == "\088"
>>> [1] TRUE
>>> > "\8" == "\b"
>>> [1] TRUE
>>>
>>> 9's are rejected, so I'd expected 8's to be illegal as well.
>>
>> It is documented that way in the R-lang manual, but I imagine it's just
>> a thinko. It's been like that since octal escapes were added in 1998.
>> I wonder how much will break if I fix it?
>>
>> Duncan Murdoch
>>
>>>
>>> > "\9"
>>> Error: '\9' is an unrecognized escape in character string starting "\9"
>>> > "\091")
>>> Error: embedded nul in string: '\091'
>>>
>>> Bill Dunlap
>>> Spotfire, TIBCO Software
>>> wdunlap tibco.com
>>>
>>>> sessionInfo()
>>> R version 2.13.1 (2011-07-08)
>>> Platform: x86_64-unknown-linux-gnu (64-bit)
>>>
>>> locale:
>>> [1] LC_CTYPE=en_US.UTF-8 LC_NUMERIC=C
>>> [3] LC_TIME=en_US.UTF-8 LC_COLLATE=en_US.UTF-8
>>> [5] LC_MONETARY=C LC_MESSAGES=en_US.UTF-8
>>> [7] LC_PAPER=en_US.UTF-8 LC_NAME=C
>>> [9] LC_ADDRESS=C LC_TELEPHONE=C
>>> [11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C
>>>
>>> attached base packages:
>>> [1] stats graphics grDevices utils datasets methods base
>>>
>>> ______________________________________________
>>> R-devel_at_r-project.org mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-devel
>



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