A couple of weeks back there was some discussion about documenting the regular expressions as used in R. Several years ago the problem was that this was OS-dependent, and to plug that problem we incorporated regexp code from a version of GNU grep, later updated to grep-2.4.2 in R 1.2.0.
I have been looking at documenting what grep(perl=TRUE) does, and we have a similar problem in that the current PCRE, 4.4, implements rather more of Perl's regexps than 3.9 (which is in 1.8.0 if the OS does not supply it, and RH8.0 has PCRE 3.9. Whichever version of Debian is on franz has PCRE 3.4). I could add a configure check for PCRE >= 4.0, and I think probably should do that. However, my inclination is to always use the version of PCRE in the R sources and thereby ensure that all builds of R have the same version, the one I will document. Comments, please. For PCRE 4.4 there is a long man page that I will use as a basis for the documentation. I am inclined just to include either a text or PDF version of the man page -- any preferences for which form? For the non-Perl regexps it is harder, as I am unsure exactly what patterns the GNU regex we have accepts. (From a problem which occurred with some Sweave regexps, I think it accepts more than it is intended to.) One fairly good docu source is the GNU grep man page: does anyone know a better one? I had thought of writing a regexp.Rd help page to which grep.Rd could refer. None of this is imminent (I am too busy) but is intended for the next minor release (which may be called 1.9.0 or 2.0.0, I gather). Brian -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-devel
