RE: next emacs version?

["Drew Adams" <drew.adams@oracle.com>]

> > > If you want to discern v23.x from v24.x, 
> > > emacs-major-version is the first thing I'd try.
> > 
> > I said I want to discern this code change, which will be 
> > made by Emacs Dev to 23.2 (probably; it is made now in
> > 24.0.50.1). So `emacs-major-version' is not
> > the way to check that.
> 
> Please explain more.  The above advice was based on a guess, and it
> turns out I guessed wrongly.  What exactly do you want to test for?
> 
> Was the change in files.el made before the 23.2 release branch was
> cut, or after it?  If the latter, was it made to both the trunk and
> the branch?

Dunno. The change is in the latest files.el:
http://bazaar.launchpad.net/~vcs-imports/emacs/trunk/annotate/head%3A/lisp/files
.el. And it is not in the 23.1 release.

Clicking the change-indicator link closest to the regexp definition in question
doesn't really provide useful info wrt the change, AFAICT. But clicking `View
changes to the file' and searching for "regexp" leads me to this change, which
seems to be the one:

 Chong Yidong2010-02-21 21:12:46Revision ID: 
 cyd@stupidchicken.com-20100221211246-i6nketjrj58mq1qt

 * files.el (directory-listing-before-filename-regexp): Use
 stricter matching for iso-style dates, to avoid false matches with
 date-like filenames (Bug#5597).

(The site is so slow and keeps telling me "Please try again. Sorry, there was a
problem connecting to the Launchpad server." that it's almost unusable. I had to
kill my browser, IE7, a couple of times and start over. And it kept telling me
that the page was running a script that was slowing things down so much that it
advised me to stop it.)

The change I am interested in testing for is a change in the value of
`directory-listing-before-filename-regexp', as I said before. Please see my
previous email for more details. That is really what I want to check - the goal.
Checking for a particular Emacs version would only be an indirect (and
approximate) means toward that goal.

> > In the past, I've checked `emacs-major-version' and 
> > `emacs-minor-version' together, or I've checked for the change
> > using string-match with `emacs-version'. I was wondering if
> > there is a recommendation here.
> 
> Perhaps the various predicates for comparing versions could help you
> (version<, version<=, etc.).

Good to know; I wasn't aware of them. That's essentially what I was doing using
string-match, but they simplify things. (However, I will need to combine them
with `fboundp', since they don't exist in older Emacs versions.)

The question remains, however, which >, <=, etc. test could do the job robustly,
since the dev version is 24.0.50.1 and the first corresponding release will be
23.2?