Re: GNU ELPA package for CC-mode

[Stefan Monnier <monnier@iro.umontreal.ca>]

> You don't understand the notion of the VCS logs becoming polluted?

No, indeed, see below.

> In every possible way, bar the superficial.  c-version is an essential
> part of CC Mode,

Hardly: I removed it in my local Emacs and everything works just as well
as before.

> and is THE version of CC Mode.  The proposed VERSION: header is not
> a part of CC Mode, it is part of ELPA, recording the number of the
> ELPA release only.

The "Version:" header could just as well be THE version.

So, I still don't see in which way they're fundamentally different.

>> > This "Version:" header certainly has no place in master, though I can
>> > see an argument being made for it being included in an ELPA version of
>> > CC Mode.
>> The purpose of this "Version:" header is to document for package.el
>> ....
> Yes.  It's essentially part of package.el, not part of CC Mode or of
> master.

I don't think the version of a package can be considered to be "part of
package.el".

>> .... which version of the cc-mode package is bundled with Emacs so
>> that it ....
> "It" being what?  Emacs?  package.el?

package.el or "Emacs via package.el".

>> .... can decide whether some other cc-mode ELPA package is more or
>> less recent (and hence whether to activate that other package or not).
>> So it very much belongs in `master`.
> I can't follow your arguments, sorry.

Here's the scenario:

- Scene 1:
  Georges is happily using Emacs-25.4 when he notices that he'd like the
  support for newer C++ language features present in the newer version of
  CC-mode, so he installs a newer CC-mode package locally.

- Scene 2: Georges is very happy.

- Scene 3: Georges is a bit older, using Emacs-28.3 and usually happy
  about it, except baffled that his CC-mode is still not supporting the
  latest features of C++++ despite the etc/NEWS claiming that it does.

- Scene 4: Georges realizes that the problem was the old CC-mode package
  he had installed which took precedence over his Emacs's newer bundled
  CC-mode.  So he removes his old CC-mode package.

- Scene 5: Goerges is forced to go back to Emacs-25.4 temporarily and is
  annoyed that he get rid of that old CC-mode package which worked
  better than the even older CC-mode bundled with Emacs-25.4.

By adding a "Version:" header in Emacs's bundled CC-mode package,
package.el can automatically decide whether to use the bundled CC-mode
package of the separately install CC-mode package based on which of the
two is more recent, so Georges wouldn't hit the above problem in scene
3 and wouldn't have to remove the old CC-mode package hence could switch
between 25.4 and 28.3 without problems.

> Your conclusion doesn't appear to
> follow from the arguments.  This proposed "Version:" header has no
> purpose in master, only in package.el, isn't that right?

Not sure what you mean by "in package.el".  "package.el" is a file
bundled with Emacs which provides facilities to
install/activate/deinstall packages and that's all.

>> >> The generation of the new package happens when the "Version:" header
>> >> changes, so I don't think we want this header to be auto-generated on
>> >> every commit.
>> > "Changes" is a verb with an agent.  Under what scenario do you envisage
>> > this version number being changed?
>> Someone pushed a commit which changes that part of the file.
> That wasn't the question I was attempting to ask; I wanted you to tell
> me about the schedule for changing the version number, the criterion for
> doing so, the frequency with which it will be done, things like that.

I'd assume that unless you decide otherwise noone but you would change
that "Version:" header (for fear of you biting their head off), so you'd
get to choose those things the way you like.

Personally, I'd recommend you'd upgrade the "Version:" header whenever
the file has accrued enough new features or bug fixes that some users of
non-master Emacs may want to install that new package in their
own Emacs.

> It seems to make sense to make such a release on each CC Mode commit to
> master.  I thought that was the idea - to keep the ELPA release
> synchronised with master.  However, if we end up keeping this obtrusive
> "Version:" in cc-mode.el, I would say do it on every tenth commit that
> changes the substance of cc-mode.el, thus keeping the aforementioned
> pollution within reasonable bounds.

You can upgrade the "Version:" header as part of some other commit.
That's usually what I do.


        Stefan