going back in time

going back in time

[Andrea Crotti]

I was just wondering if there could be kind of undo operation for higher
level problems.

For example now I just installed ruby-tests.el from emacswiki, which (I
saw too late) unfortunately has some "global-set-keys" with combinations
that normally I use for other things.

Is there any way to revert back to the last global state (it might be
useful also in other cases of cours)?
Thanks

Re: going back in time

[Štěpán Němec]

Andrea Crotti <andrea.crotti.0@gmail.com> writes:

> I was just wondering if there could be kind of undo operation for higher
> level problems.
>
> For example now I just installed ruby-tests.el from emacswiki, which (I
> saw too late) unfortunately has some "global-set-keys" with combinations
> that normally I use for other things.
>
> Is there any way to revert back to the last global state (it might be
> useful also in other cases of cours)?

No (other than redoing your original bindings yourself, obviously).
And if a package unconditionally/irreversibly adds global bindings, you
can safely say it's badly written and complain to its author. That's
what modes and keymaps are for.

Štěpán

Re: going back in time

[Eric Abrahamsen]

Štěpán Němec <stepnem@gmail.com> writes:

> Andrea Crotti <andrea.crotti.0@gmail.com> writes:
>
>> I was just wondering if there could be kind of undo operation for higher
>> level problems.
>>
>> For example now I just installed ruby-tests.el from emacswiki, which (I
>> saw too late) unfortunately has some "global-set-keys" with combinations
>> that normally I use for other things.
>>
>> Is there any way to revert back to the last global state (it might be
>> useful also in other cases of cours)?
>
> No (other than redoing your original bindings yourself, obviously).
> And if a package unconditionally/irreversibly adds global bindings, you
> can safely say it's badly written and complain to its author. That's
> what modes and keymaps are for.

Out of curiosity, does unload-feature also unload that feature's
keybindings? How would a package author provide keybindings in
reversible way?

Eric

>
> Štěpán

Re: going back in time

[Štěpán Němec]

Eric Abrahamsen <eric@ericabrahamsen.net> writes:

> Štěpán Němec <stepnem@gmail.com> writes:
>
>> Andrea Crotti <andrea.crotti.0@gmail.com> writes:
>>> Is there any way to revert back to the last global state (it might be
>>> useful also in other cases of cours)?
>>
>> No (other than redoing your original bindings yourself, obviously).
>> And if a package unconditionally/irreversibly adds global bindings, you
>> can safely say it's badly written and complain to its author. That's
>> what modes and keymaps are for.
>
> Out of curiosity, does unload-feature also unload that feature's
> keybindings? How would a package author provide keybindings in
> reversible way?

(info "(elisp)Unloading")

I don't think it does. The problem is not unloading, but restoring the
original bindings. The package could provide a FEATURE-unload-function
which would restore the bindings previously saved (which would also have
to be done manually). But as I said, I can't think of a legitimate
reason for a package to mess with global-map. If you think defining a
mode and a keymap for the functionality you provide is unnecessary, just
define the commands and put some keybinding recommendations into a
commentary.

Štěpán

Re: going back in time

[Andrea Crotti]

>
> No (other than redoing your original bindings yourself, obviously).
> And if a package unconditionally/irreversibly adds global bindings, you
> can safely say it's badly written and complain to its author. That's
> what modes and keymaps are for.
>
> Štěpán

Yes of course it's not easy, but I think there could be something like
(save-global-excursion
        command

which could first save the global configuration and then execute a
command.

Would it maybe be too slow?
At least the global key mapping and variable values I think it could be done...

Re: going back in time

[Štěpán Němec]

Andrea Crotti <andrea.crotti.0@gmail.com> writes:

>>
>> No (other than redoing your original bindings yourself, obviously).
>> And if a package unconditionally/irreversibly adds global bindings, you
>> can safely say it's badly written and complain to its author. That's
>> what modes and keymaps are for.
>>
>> Štěpán
>
> Yes of course it's not easy, but I think there could be something like
> (save-global-excursion
>         command
>
> which could first save the global configuration and then execute a
> command.
>
> Would it maybe be too slow?
> At least the global key mapping and variable values I think it could be
> done...

Why don't you just try it?

(setq bkp-global-map (copy-seq global-map))
  ...
  GO CRAZY
  ...
(setq global-map bkp-global-map)

(Note that I have no idea if it will even work as expected for keymaps;
your backup may still share some structure with the original; not sure.
You might try `copy-tree'.)

Same with other variables.

  Štěpán

Re: going back in time

[Štěpán Němec]

(Actually there is `copy-keymap', too, but the caveat still applies.)

Re: going back in time

[Andreas Röhler]

Am 26.07.2010 20:43, schrieb Andrea Crotti:
> I was just wondering if there could be kind of undo operation for higher
> level problems.
>
> For example now I just installed

have my emacs-init under RCS, so its easily reverted, should some 
strange error occur

  ruby-tests.el from emacswiki, which (I
> saw too late) unfortunately has some "global-set-keys" with combinations
> that normally I use for other things.

if it's just some keys, why not change them inside ruby-tests.el?

Andreas

>
> Is there any way to revert back to the last global state (it might be
> useful also in other cases of cours)?
> Thanks
>
>
>

Re: going back in time

[Andrea Crotti]

>
> if it's just some keys, why not change them inside ruby-tests.el?
>
> Andreas

Of course it's not a specific problem, it was more a curiosity...
Also my configuration is under revision control, BUT I still should
restart emacs, which is bad ;)

Is there something like
- "reset everything as if it were just booted" without rebooting it?

Re: going back in time

[Andrea Crotti]

>
> if it's just some keys, why not change them inside ruby-tests.el?
>
> Andreas

Of course it's not a specific problem, it was more a curiosity...
Also my configuration is under revision control, BUT I still should
restart emacs, which is bad ;)

Is there something like
- "reset everything as if it were just booted" without rebooting it?

Re: going back in time

[Andreas Politz]

Andrea Crotti <andrea.crotti.0@gmail.com> writes:

> I was just wondering if there could be kind of undo operation for higher
> level problems.
>
> For example now I just installed ruby-tests.el from emacswiki, which (I
> saw too late) unfortunately has some "global-set-keys" with combinations
> that normally I use for other things.
>
> Is there any way to revert back to the last global state (it might be
> useful also in other cases of cours)?
> Thanks

Making a deep copy of the obarray at some defined points in time may be
all that it needs.

-ap