[ESS] Emacs 24, ESS and R/Sweave - 2 changes in behavior from Emacs 23

[Vitalie Spinu]

Thanks for reports. Noweb is inherently broken and will be most likely
replaced in the next version of ESS. I've already started working on a
general literate programing frontend,  available here:
https://github.com/vitoshka/litprog . 

To avoid repeating mistakes in noweb I would like to have as many self
contained reproducible examples as I can. So, if you experience problems
with noweb, please send your snippets to me personally or to this list.

I can reproduce Carslav's example on emacs 24. Mark, can you please send
a short self contained file with your problems?

Thanks, 
Vitalie.

  >> "Carslaw, David" <david.carslaw at kcl.ac.uk>
  >> on Wed, 13 Jun 2012 21:40:41 +0100 wrote:

  > Thanks Marc.  I too have related problems that would seem a good time to mention (using Vincent Goulet's latest release for Windows based on emacs 24.1).
  > Given a minimal example like this:

  > #############################################
  > \documentclass{article}

  > King's College London

  > \begin{document}
  > <<>>=
  > test <- data.frame(x = 1:3, y = 1:3)
  > @
  > \end{document} 
  > ##############################################

  > The R code is shown as a string face (M-x Describe-face) and ends up like this
  > because of the ' in King's.  I think there are other issues with constructs like
  > the quotes using backticks e.g. `backtick', which also affects fontification.
  > These issues are not present in the emacs 23.4 I was previously using.

  > All the best 

  > David Carslaw

  > -----Original Message-----
  > From: ess-help-bounces at r-project.org [mailto:ess-help-bounces at r-project.org] On Behalf Of Marc Schwartz
  > Sent: 13 June 2012 21:21
  > To: ESS-help
  > Subject: [ESS] Emacs 24, ESS and R/Sweave - 2 changes in behavior from Emacs 23

  > Hi all,

  > Greetings from useR at Vanderbilt in Nashville.

  > Having upgraded to Emacs 24 earlier this week, I began to notice some behavioral
  > changes from Emacs 23 when editing Sweave .Rnw files. I spent some time
  > isolating both problems and had the opportunity here to discuss them with Rich
  > Heiberger and Martin Maechler who suggested that I post to the list.

  > For completeness:

  > 1. Running on a MacBook Pro with fully updated OSX Lion
  > 2. Emacs 23 and 24 binaries from http://emacsformacosx.com/3. ess-12.04-4
  > 4. auctex-11.86

  > The first issue, which turns out to be my problem, is that for years, I have had the following Emacs directive at the top of my .Rnw files:

  >   % -*- mode: noweb; noweb-default-code-mode: R-mode; -*-

  > Now, in all honesty, I can't for the life of me recall the etiology of this
  > inclusion in my .Rnw templates. I have been using Emacs and Sweave since circa
  > 2003 (R itself since circa 2001). Perhaps some of the grey-haired folks like me
  > whose recollection is better than my own can provide some history, presuming
  > that this was dealing with some multi-mode issues in Emacs.

  > That all being said, this all worked fine through Emacs versions 21 and 23 on Windows, RH/Fedora Linux and OSX. That changed with 24.

  > For assistance purposes, if the above line is present, one gets an error message:

  >   "noweb mode removed"

  > and noweb font lock mode fails. Took me a while to figure out where that was coming from.

  > Looks like this message comes from the noweb-mode.el file in ESS AFAICS, around
  > line 491, not from other Emacs sources. So it would seem that something
  > pertaining to noweb mode changed and Martin had suggested that he recalled some
  > recent communications regarding noweb related code in Emacs 24 that might now
  > conflict with the above incantation. In either case, the above causes problems,
  > is no longer needed and perhaps in reality, has not been for some time.

  > The second issue, which is a bit more perplexing is a variation on a problem
  > that I have had for some time and I believe others have had as well. The prior
  > issue is that if one includes a "$" in a LaTeX section of the file
  > (eg. DataFrameName$ColumnName), for example within a \Sexpr{} to return a scalar
  > value, the presence of the "$" kills the correct font lock coloration and
  > representations (eg. subscripts, etc.) for text that follows, until a following
  > R code chunk. That issue is easily avoided by having a preceding R code chunk
  > which does the more complicated manipulation of data and assigns that to a
  > scalar, suitably named, that is then included in the \Sexpr{}.

  > The new behavior in Emacs 24, is that if one includes the "$" in an R code
  > chunk, the following LaTeX content is not correctly represented. In my case, all
  > LaTeX section text turns a brownish color (eg. rather than black) and any other
  > TeX specific font sizes, etc. are lost. For example, create a simple R chunk
  > followed by some LaTeX mode text:

  > <<>>=
  >   iris$Species
  > @

  > Some LaTeX mode text here

  > You may have to scroll the cursor through the lines of text to see the effect.

  > Completely by accident, I found that if one adds a second "$" in that R code
  > chunk (eg. iris$Species$), such that there is now a pair of "$"s, that seems to
  > trigger a correction of the underlying situation and the LaTeX section that
  > follows is correctly colored/represented as it should be. So this is a change in
  > behavior in 24 and seems to suggest that somehow the font lock mode is
  > interpreting the "$"s as an opening and closing pair of some kind of tag. This
  > pairing behavior seems to continue based upon either an odd or even number of
  > "$"s in the R chunk, thus iris$Species$$ fails, iris$Species$$$ succeeds, and so
  > forth.

  > I am not sure if folks are aware of this second issue with Emacs 24 since the
  > stable release is just out, but wanted to report my observations. As noted, I
  > did not observe this behavior with 23. If you need more information, let me
  > know.

  > Thanks for taking the time to read this.

  > Regards,

  > Marc Schwartz

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