Re: [9fans] rev control

["Russ Cox" <rsc@plan9.bell-labs.com>]

  What is the Plan 9 answer to stuff like SCCS and RCS?  The yesterday
  facility takes care of the "how do I back out of this mess?" problem,
  but I'm not sure what would be analogous to tags and commit logs.  Are
  there other tools I've overlooked?

As Scott said, yesterday is it.  For the most part,
changes happen slowly enough that the granularity of a day
is just fine.  history -D prints a diff log, which is
not quite a commit log but just as useful.  If you really
want to know, the file server keeps track of who last
touched each file, and this information is in the dump
too, so it's not hard to assign blame for old changes.

I've worked on projects that required CVS, and I've
worked on Plan 9.  Not surprisingly, I like the Plan 9 
way better.  From a usability standpoint, I like
being able to run any command I want on the dump
file system.  There's nothing to learn except the
typing of "9fs dump".  Contrast this with CVS, where
you have to learn the CVS lexicon, which is just close
enough to familiar tools to be incredibly frustrating,
in order to do anything meaningful.

The more compelling issue, though, is that many people
treat CVS as a license to commit changes: if the changes break
something, someone else can easily back them out.  
But the time spent figuring out that it's not your fault
that the program is crashing, and then finding the correct
change to back out, is lost.  The Plan 9 way requires
more communication than the CVS way, which means most
people have a better sense of what's going on and
how the changes will affect them.

I spent the summer working on a programming languages
book: the text, the associated code, and the build
scripts were all under CVS control.  Oh, and I was
using Plan 9 (hence the CVS port) but the professor
with whom I was working was using Linux.  We fell into
the CVS trap -- instead of talking through changes
before they happened, many of the discussions happened
afterward, when one of us couldn't build the world after
the other's changes.  We got a lot done, but the lack
of extensive communication about who currently owned what
meant we stepped on each other's feet more often 
than we would have liked.

I think a single common source with communication between
the (human) writers is still the best way to go.  

Russ