Re: Superseded packages

[ludo@gnu.org (Ludovic Courtès)]

Leo Famulari <leo@famulari.name> skribis:

> On Sat, Sep 24, 2016 at 11:14:41AM +0900, Ludovic Courtès wrote:
>> Leo Famulari <leo@famulari.name> skribis:
>> > +(define-public attic
>> > +  (package (inherit borg)
>> > +    (name "attic")
>> > +    (properties `((superseded . ,borg)))))
>> 
>> I was thinking that we could keep the ‘attic’ recipe as-is, only with
>> this extra ‘properties’ field.
>> 
>> That way, “guix package -u” and “guix package -i attic” would install
>> Borg, but people who insist could still run:
>> 
>>   guix package -e '(@ (gnu packages backup) attic)'
>> 
>> Thoughts?
>
> That's a much better idea than what I had proposed.
>
> I found that I had to move the attic package definition below borg's, or
> else the borg variable was unbound when building (gnu packages backup):

[...]

> So the attached patch moves attic after borg and supersedes it. Is it
> expected that we have to shuffle the package definition around like
> this?

Yes, because ‘properties’ are evaluated eagerly.

We could change the ‘superseded’ property to always be a promise, as
Efraim suggests; we’ll see later if that’s really necessary.

The patch LGTM.

Thank you!

Ludo’.