Ludovic Courtès (2014-10-05 00:23 +0400) wrote:

> Alex Kost <alezost@gmail.com> skribis:>

[...]

>> - (Not related to this patch, but still …)  Currently with “roll-back”,
>>   we can only switch to the previous generation.  What about adding a
>>   possibility to switch to any generation?  So that we could use
>>   something like this:
>>
>>     guix package --switch-generation=7
>>
>>   Also such functionality can be added to Emacs UI: for example pressing
>>   "C" on a generation in *Guix Generation List* will make this
>>   generation the current one.
>>
>>   So ‘roll-back’ procedure may become a special case of the
>>   ‘switch-generation’ one.  WDYT?
>
> I think it’s a good idea!  (I think it was suggested in earlier
> discussions, but never implemented.)

Andreas Enge (2014-10-05 18:44 +0400) wrote:

[...]

> Actually, sometimes I would like to switch to the next generation ("-roll-
> forward", in a sense): I install something, go back with "--roll-back",
> and might like to go just one forward again.
>
> So how about the following:
> --switch-generation=1
> goes to generation 1;
> --switch-generation=-1
> goes 1 generation back;
> --switch-generation=+1
> goes one generation forward.

Thanks for the great idea!

————————————————————————————————————————————————————————————————
A patch is attached.  Some comments:

- ‘shitted-generation’ is not a very good name, I think.  Ideas?

- ‘previous-generation-number’ may use ‘shifted-generation’ now: