[9fans] ctags on plan 9 with acme-friendly tags

["Anthony Sorace" <anothy@gmail.com>]

i occasionally have to deal with moderate to large bodies of code
written by others and of questionable structural integrity. most often
this is C code, but sometimes its other things. there are a few tools
i've seen which help on the learning curve; ctags is one of the more
significant one.

i've gotten Exuberant Ctags 5.7 to run on plan 9 ("ported" is a bit
strong; it was two tweaks after './configure'). i've also added
options to produce filename:line tags for acme and the plumber. i'm
cleaning things up a bit for upstream submission, but in the mean time
you can get what i've done at /n/sources/contrib/anothy/src/ctags;
there's a README.plan9 that gives instructions for building ('make
ctags' under ape and then 'cp ctags $home/bin/$objtype', basically)
and what the changes from the distribution were.

exuberant generates tags for a dozen or so languages, but i've only
tested it with C; i'll be pushing some perl and php at it this week.
if anyone would like to try it with anything else it supports, please
let me know how it goes.

i'm considering doing a limbo parser; exuberant makes it relatively
easy to add language. of course, i've never seen limbo code convoluted
enough to make it relevant there. i'm also considering writing a
program for use with acme's 2-1 chord to look up elements in a tag
file. if anyone's interested in either of those (either has a use for
them or would like to do them), let me know.

i'd like to get something that'll generate visual static call graphs
eventually (feed into graphviz, perhaps), but i'm not likely to spend
any time on it in the near future. if anyone's look at that, i'd love
to hear about it.

incidentally, the levels of (mis?)indirection in exuberant's argument
processing are truly "impressive".
anthony