[Rd] relative path to source files in vignette

[Peter Ruckdeschel]

Hi,

this may be slightly off-topic, but as you are the experts:

we have written a small vignette, in which we want to refer to
.R, .Rd source files by means of relative paths.

More specifically, we want to use TeX package "listings" to include
source code,

[which btw in the mean time works pretty well together with "fancyvrb"
so can be used
 with Sweave without problems...]

To avoid redundancy we would like to use

  \lstinputlisting[firstline=<n1>,lastline=<n2>]{<r-source-file.R>}

and to do so we somehow need path information.

This is /not/ a "listings" issue, as we might also have used
   \input{<r-source-file.R>}, only is \lstinputlisting a bit more
flexible...

Using relative paths, i.e. as the vignette resides in subfolder "inst/doc"
something like

     ../../../<mypkg>/R/<myR.R>    or   ../../../<mypkg>/man/<myRd.Rd>

does the job for  both  R CMD build   and   R CMD check ,
--- in standard configurations.

However, as you may change the location of the check folder with
the -o option of R CMD check, (and possibly other things, we have
not yet thought of ...), our solution is not quite satisfactory,
so we have been wondering whether there is a (platform-independent)
way to access the package source folder (under check) from within
TeX.

--- or if you prefer to solve it from R-side:

We would appreciate an Sweave-chunk to do the following:
+have three arguments firstline, lastline, filename
  [where filename is relative to the package source folder]
+read out the information about the path to the package
  source folder [from the env-variable?]
+with this information read in the part of the source file
  between <firstline> and <lastline>
  and places this content ---without wrapping it to
  \begin{Schunk} ... \end{Schunk}--- into the .tex file
  ---preferrably  already into a \begin{listing}\end{listing}
   environment...

Any suggestions how to resolve this?

Thank you already,
Peter