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

From: William Dunlap <wdunlap_at_tibco.com>
Date: Fri, 02 Sep 2011 00:47:33 +0000

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   ./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.

ink1">ink3">Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com

> -----Original Message-----
> From: Duncan Murdoch [mailto:murdoch.duncan@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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