Thomas Schneider <qsx@chaotikum.eu> writes:

> I’m struggling to combine use-package, package.el, and Emacs packages
> installed by the system package manager (e.g., apt).
> 
> I want:
> - to install packages via the system package manager as much as possible
>   This is especially important for packages such as pdf-tools, which
>   require development headers of several libraries, but are readily
>   installed via system packages

Me too.  I am convinced that public Emacs package archives should
provide packages for popular package managers, not only for package.el.
It is totally feasible to generate most of those automatically.

If a package manager installs a package that depends on a C library, it
must be able to provide that C library too.  Thus, as long as Emacs
packages depend on external software, they should be installed by a
package manager that is good enough to install (as well as fetch,
configure, build, of course) said external software.

> - not to install packages again as user, when they are already
>   installed system-wide
>   
> - especially as dependencies
>   For example, Gentoo provides AUCTeX, but not auctex-latexmk.  When I
>   install the latter via package.el, it installs AUCTeX again, even
>   though it’s already installed system-wide

I have an Emacs package available from my Gentoo repository:
https://gitlab.com/akater/elpa-to-ebuilds
README explains how to add the repository and install the package.

It is currently capable of producing, mostly correctly, working ebuilds
from non-built-in Emacs features that are currently loaded into Emacs
(together with their dependencies, which is what normally happens).

I migrated almost all Emacs packages I use to Portage.  I have not
published those 50-something ebuilds but if you are interested in
similar migration, I'll be able to help.

I don't have any testers besides myself and thus can't guarantee smooth
experience with elpa-to-ebuilds but I'd love to meet some testers and
potential collaborators who share the above views on Emacs package
management and dissatisfaction with package.el.  In fact, due to lack of
testers I'm not even sure elpa-to-ebuilds installs OK.

> - to continue using use-package, or something else that helps me
> structure my init.el

I'm using use-package almost exclusively.  I think it could be
integrated with system package managers but you'd need installation
rights (this likely means root, in my experience) anyway.

> - not to download half of MELPA the first time I start Emacs on a new
> host

This sounds impossible if “new host” implies “no Emacs packages
installed” --- could you clarify?