bug#69410: 30.0.50; [WISHLIST] Use-package: allow :ensure to accept package spec instead of separate :vc keyword

[Tony Zorman via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

On Sun, Jun 30 2024 10:42, Philip Kaludercic wrote:
> No Wayman <iarchivedmywholelife@gmail.com> writes:
>
>> I think it would be cleaner to allow use-package's :ensure keyword to
>> accept the arguments the :vc keyword currently does. e.g.
>>
>> ;; Install EXAMPLE package from ELPA archive
>> (use-package example :ensure t)
>>
>> ;; Install EXAMPLE package from source
>> (use-package example :ensure (:url
>> "https://www.forge.com/maintainer/example"))
>>
>> My reasoning is that this has greater potential to work across
>> multiple package managers.
>> Instead of each package manager adding their own use-package keyword
>> (e.g. :vc, :straight, :elpaca), they can all interpret the :ensure
>> keyword's value. It would make things simpler for package maintainers
>> offering example declarations and users switching between package
>> managers.
>
> I am adding Tony to the CCs, as he implemented the :vc keyword to see if
> he has anything to comment (generally it is good to add a X-Debbugs-CC
> header, mentioning specific maintainers or people involved in a feature
> when submitting a bug).

Thanks. To be honest, I'm not a big fan of trying to cram everything
into :ensure. Implementation wise, I feel like it would make things much
messier than they are now—especially if the final goal is to maybe
extend this to other package managers. By the same thought, one might
argue that something like :load-path should be inlined into :ensure as
well, which is not a good idea in my opinion.

In either case, I think that

  (use-package example
    :ensure (:url "https://www.forge.com/maintainer/example"))

is not that much more verbose (or harder to adjust) than

  (use-package example
    :ensure t
    :vc (:url "https://www.forge.com/maintainer/example"))

This is especially true since use-package-always-ensure exists (and many
people use it) so one would just have to write

  (use-package example
    :vc (:url "https://www.forge.com/maintainer/example"))

Any kind of backwards compatibility with a hypothetical :straight
keyword would not work in either case, because :straight already exists
in straight.el and it has a completely different package specification
attached to it.

> My own take is that setting aside timing issues and the fact that the
> Emacs 30 branch has been cut, ...
>
> - The :vc keyword allows just passing t to download the package as
>   specified in the ELPA archive.  I don't see an elegant away to allow
>   this using :ensure.

Yes backwards compatibility might be a bit of a pain—especially with a
view on use-package-always-ensure—save having self-defeating constructs
like :ensure (:vc …).

  Tony

-- 
Tony Zorman | https://tony-zorman.com