[ESS] TAGS only the first function in some files

[Stephen Eglen]

Henrik Andersson writes:
 > I tried to use etags to tag my R files.
 > 
 > For some files it indexes all functions but for some files it only finds 
 > the first function defined and skips the rest???
 > 
 > I ran 'etags *.R' in the folder containing my scripts, did I miss 
 > something vital?
 > 
Dear Henkrik, et al.

It looks to me like etags does not have support built-in for R code;
the fact that it worked at all for some of your scripts is probably
coincidence with support for other languages, rather than design!

Instead, I believe the solution to using etags is along the following
lines:

etags --language=none 
      --regex='/\([^ \t]+\)[ \t]*<-[ \t]*function/\1/' *.R

(I've broken the line manually before --regex, but that should all go
on one line.)

I.e. we need to describe a regex for the first line of the function;
here the regex is:

some.name <- function

note: function name is in column 0 (but adding whitespace regex should
not be hard)
whitespace _before_ assignment (<-) is necessary; that can be removed
I guess by including < as one of the characters to skip in the first
part of the regex; space after the assignment is optional.

Please test and report back; if this works out, we can add it to the
manual at least.  If it proves very useful for several ess-users, I
can see if we can get the regexp added to Emacs.

Stephen