Re: [Rd] Sweave processes \Sexpr in commented LaTeX source (2.3.1patched and 2.4.0)

From: Friedrich Leisch <>
Date: Thu 21 Sep 2006 - 14:40:19 GMT

>>>>> On Wed, 20 Sep 2006 10:07:26 -0700, >>>>> Seth Falcon (SF) wrote:

  > "Antonio, Fabio Di Narzo" <> writes:
  >> 2006/9/20, Seth Falcon <>:

>>> Peter Dalgaard <> writes:
>>> > ..not to mention TeX comments inside Sexpr (e.g. %*%...). Skipping
>>> > lines with % as the first character might be a viable compromise
>>> > though.
>>> +1. You could probably ignore any lines where the first
>>> non-whitespace char is '%'. But if that seems to risky, then only
>>> recognizing first-char-is-% seems a worthwhile heuristic.
>>> Another place where this has bitten people is when they do:
>>> %\usepackage{Sweave}
>>> Sweave picks that up and doesn't insert the usepackage line itself.
  >> I've found that extremely useful for sweaving Stex files which aren't
  >> "master" files (i.e., only files to include in a main latex file).
  >> Inserting '\usepackage{Sweave}' in each would result in a latex error.
  >> So commenting it out is a useful workaround.

  > Commenting it out _and_ having Sweave see it?

Yes, I actually do that quite often, e.g., when I have my own definitions of the Sinput/Soutput/... environments in the document preamble and don't want to use any Sweave style file.

Note that we recently had a thread on the \usepackage{Sweave} path insertion problems in windows and as a result I will stop being special about it at all, i.e., users will have to put a \usepackage{Sweave} into their documents, and take care that latex finds a version of it.

The thread was end of August and I didn't do it for 2.4 because I didn't want to break all vignettes that close to a release. But I will do for the 2.5 series once 2.4.0 is released.

Ad evaluation of \Sexpr{}: That can be considered a bug, hence I could try a fix even in feature freeze. But as I will be offline for a week starting tomorrow this will also have to wait until the 2.5 series (or 2.4.1, depending on the change).

My favorite would not be a separate option eval.Sexpr but eveluate only when the global option for eval is true. Then an


at any place in a document would stop all evalualtions, be it code chunks (which do not override the default) or Sexpr. If somebody has good useage for a separate option I could be convinced to have it, otherwise I'll go for \Sexpr{} listening to the eval option.

Fritz mailing list Received on Fri Sep 22 00:57:19 2006

Archive maintained by Robert King, hosted by the discipline of statistics at the University of Newcastle, Australia.
Archive generated by hypermail 2.1.8, at Thu 21 Sep 2006 - 18:30:08 GMT.

Mailing list information is available at Please read the posting guide before posting to the list.