More convenient default rollback for users

More convenient default rollback for users

[Lars Magne Ingebrigtsen]

When we introduce behavioural changes in Emacs, we often include a way
to get back to the old behaviour, and we document this in NEWS etc.

But wouldn't it be nice if we had this in a more convenient,
cut-and-pastable format?

Imagine you're using Emacs 26 for the first time.  Suddenly you notice
that when you hit the `hyper z' key, Emacs doesn't florbnoze as it used
to, but forblizes instead!  You're furious!  So you hit the `C-h R' (for
rollback) keystroke, and you get a buffer that looks like:

-------------
;; To roll back changes between Emacs 26 and Emacs 25.1:

;; If you want the `hyper z' key still to florbnoze instead of
;; forblizing:
(setq hyper-z-mode 'florbnoze)

... more setqs here...

;; To roll back changes between Emacs 25.1 and Emacs 24.3:

...
-------------

And then the anger dissipates.  No need to read documentation or
anything.  Just get back the old behaviour you enjoyed.

(And this would also mean that we could introduce new behaviours more
often, because rollback would be so trivial for the users.)

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

Re: More convenient default rollback for users

[Eli Zaretskii]

> From: Lars Magne Ingebrigtsen <larsi@gnus.org>
> Date: Tue, 29 Mar 2016 17:44:15 +0200
> 
> When we introduce behavioural changes in Emacs, we often include a way
> to get back to the old behaviour, and we document this in NEWS etc.
> 
> But wouldn't it be nice if we had this in a more convenient,
> cut-and-pastable format?
> 
> Imagine you're using Emacs 26 for the first time.  Suddenly you notice
> that when you hit the `hyper z' key, Emacs doesn't florbnoze as it used
> to, but forblizes instead!  You're furious!  So you hit the `C-h R' (for
> rollback) keystroke, and you get a buffer that looks like:
> 
> -------------
> ;; To roll back changes between Emacs 26 and Emacs 25.1:
> 
> ;; If you want the `hyper z' key still to florbnoze instead of
> ;; forblizing:
> (setq hyper-z-mode 'florbnoze)
> 
> ... more setqs here...
> 
> ;; To roll back changes between Emacs 25.1 and Emacs 24.3:
> 
> ...
> -------------

How do you do that with defcustoms?

Re: More convenient default rollback for users

[Lars Magne Ingebrigtsen]

Eli Zaretskii <eliz@gnu.org> writes:

> How do you do that with defcustoms?

I don't know.  Does defcustom offer something like that?

In any case, having the user go through the custom interface is way too
much work.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

Re: More convenient default rollback for users

[Eli Zaretskii]

> From: Lars Magne Ingebrigtsen <larsi@gnus.org>
> Cc: emacs-devel@gnu.org
> Date: Tue, 29 Mar 2016 18:31:06 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > How do you do that with defcustoms?
> 
> I don't know.  Does defcustom offer something like that?
> 
> In any case, having the user go through the custom interface is way too
> much work.

The problem is that some options are supposed to be changed via
defcustoms, because those invoke a special function for the new value
to take effect.  In NEWS, we usually say "customize the option
so-and-so to such-and-such value", but how do you do that in
copy/paste-able way? invoke the function by hand?

Re: More convenient default rollback for users

[Lars Magne Ingebrigtsen]

Eli Zaretskii <eliz@gnu.org> writes:

> The problem is that some options are supposed to be changed via
> defcustoms, because those invoke a special function for the new value
> to take effect.  In NEWS, we usually say "customize the option
> so-and-so to such-and-such value", but how do you do that in
> copy/paste-able way? invoke the function by hand?

Perhaps there should be a `custom-setq' function that the user could
eval?  Or perhaps this rollback buffer could be in a mode where just
hitting RET on a form would execute the proper custom incantations...

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

Re: More convenient default rollback for users

[Clément Pit--Claudel]

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On 03/30/2016 05:45 PM, Lars Magne Ingebrigtsen wrote:
> Eli Zaretskii <eliz@gnu.org> writes:
>> The problem is that some options are supposed to be changed via
>> defcustoms, because those invoke a special function for the new value
>> to take effect.  In NEWS, we usually say "customize the option
>> so-and-so to such-and-such value", but how do you do that in
>> copy/paste-able way? invoke the function by hand?
> 
> Perhaps there should be a `custom-setq' function that the user could
> eval?  Or perhaps this rollback buffer could be in a mode where just
> hitting RET on a form would execute the proper custom incantations...

Is that what customize-set-variable does? If not, then it would be very very very nice; most Emacs configs that I see online are nicely structured and split into a number of files, but they use setq even for variables that have custom setters.

Clément.


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Re: More convenient default rollback for users

[Stefan Monnier]

> Is that what customize-set-variable does?

I think so.


        Stefan

Re: More convenient default rollback for users

[Stefan Monnier]

> But wouldn't it be nice if we had this in a more convenient,
> cut-and-pastable format?

Sounds good.

> (And this would also mean that we could introduce new behaviours more
> often, because rollback would be so trivial for the users.)

Haha!


        Stefan

Re: More convenient default rollback for users

[Richard Stallman]

[[[ To any NSA and FBI agents reading my email: please consider    ]]]
[[[ whether defending the US Constitution against all enemies,     ]]]
[[[ foreign or domestic, requires you to follow Snowden's example. ]]]

  > Imagine you're using Emacs 26 for the first time.  Suddenly you notice
  > that when you hit the `hyper z' key, Emacs doesn't florbnoze as it used
  > to, but forblizes instead!  You're furious!  So you hit the `C-h R' (for
  > rollback) keystroke, and you get a buffer that looks like:

This sounds nice.  It goes with the Antinews feature we
have always had in documentation.

-- 
Dr Richard Stallman
President, Free Software Foundation (gnu.org, fsf.org)
Internet Hall-of-Famer (internethalloffame.org)
Skype: No way! See stallman.org/skype.html.

Re: More convenient default rollback for users

[John Wiegley]

>>>>> Richard Stallman <rms@gnu.org> writes:

>> Imagine you're using Emacs 26 for the first time. Suddenly you notice that
>> when you hit the `hyper z' key, Emacs doesn't florbnoze as it used to, but
>> forblizes instead! You're furious! So you hit the `C-h R' (for rollback)
>> keystroke, and you get a buffer that looks like:

> This sounds nice. It goes with the Antinews feature we have always had in
> documentation.

Agreed, it would be cool if it worked.  Having it work correctly in all cases
might become a maintenance burden, unless it were very easy to automate.

-- 
John Wiegley                  GPG fingerprint = 4710 CF98 AF9B 327B B80F
http://newartisans.com                          60E1 46C4 BD1A 7AC1 4BA2

Re: More convenient default rollback for users

[zhanghj]

Lars Magne Ingebrigtsen <larsi@gnus.org> writes:

> When we introduce behavioural changes in Emacs, we often include a way
> to get back to the old behaviour, and we document this in NEWS etc.
>
> But wouldn't it be nice if we had this in a more convenient,
> cut-and-pastable format?
>
> Imagine you're using Emacs 26 for the first time.  Suddenly you notice
> that when you hit the `hyper z' key, Emacs doesn't florbnoze as it used
> to, but forblizes instead!  You're furious!  So you hit the `C-h R' (for
> rollback) keystroke, and you get a buffer that looks like:
>
> -------------
> ;; To roll back changes between Emacs 26 and Emacs 25.1:
>
> ;; If you want the `hyper z' key still to florbnoze instead of
> ;; forblizing:
> (setq hyper-z-mode 'florbnoze)
>
> ... more setqs here...
>
> ;; To roll back changes between Emacs 25.1 and Emacs 24.3:
>
> ...
> -------------
>
> And then the anger dissipates.  No need to read documentation or
> anything.  Just get back the old behaviour you enjoyed.
>
> (And this would also mean that we could introduce new behaviours more
> often, because rollback would be so trivial for the users.)

I think a UI page like "chrome://flags/" in google chrome is better for
this function. In this page, we can show all compitable options for user
to choose.

For expert user, we can provide a file like emacs-24-compitable.el (with
emacs 25 distribution). After loading the file, all behaviors are the
same as emacs 24. This can also be used by packages.