Re: [SOLVED for GNU]

[Stephen J. Turnbull]

Removing Thi from the CC list; he'll see it on emacs-devel.

Uwe Brauer writes:

 >    > This looks incorrect, if 1.y is your trunk, and x.y for x > 1 are
 >    > branches.  In that case you should change the regexp to
 >    > "\\`1\\.[0-9]+\\'".
 > 
 > Well that is not part of the hack but part of GNU Emacs vc.el.
 > Just in case I put Thien and Emacs-devel in the CC, in case your comment
 > is relevant for the general case.

No, it's not.

I'm not sure what the general case looks like for RCS (or even if
there is one, any more -- I'm sure there are a lot of people who still
use RCS for one reason or another but I bet they have a million
different conventions for version numbering).

 >    > There's nothing in the implementation you posted that wouldn't work in
 >    > XEmacs AFAICS.  I suspect that XEmacs vc just doesn't find the new
 >    > function.  Try naming the function "vc-rcs-previous-version" instead
 >    > and see if XEmacs calls it properly.
 > 
 > That is odd, I tried it several times and got an error about number of
 > arguments, however now it *works*. I keep and eye on that.

Good.  It doesn't really surprise me that it took a few tries.
Because of the way that vc.el manages its various engines, you might
have to switch to another one then back to RCS, or kill a buffer and
reread the file, or ..., to get the new function insinuated.

Let us know if it decides to fail again.

 > Thanks all of you for your help, but I presume this function will not be
 > included in any official vc version?

I don't see why not.  Although the difference between "parent" and
"head of previous branch" is important, since RCS doesn't know about
parents as far as I can see, "head of previous branch" seems like a
good approximation.

Emacs may have a different opinion, of course.