Re: [package-vc] Consider cleaning up files from install process

[Adam Porter]

On 9/19/23 08:50, Philip Kaludercic wrote:

> > An alternative would be to follow Quelpa's example: rather than
> > loading the package directly from the git repository's directory, the
> > package's files could be copied into a new directory in the elpa/
> > directory, and Emacs could load the package from there.
> >
> > As a developer, I would prefer that approach, because I don't usually
> > want Emacs to load whatever commit I may have checked out in a
> > package's repository.  I want to install a commit of a package into my
> > Emacs configuration and have that one loaded until I install a
> > different one.
>
> Isn't this workflow already supported by `package-install-file'?  And
> otherwise, there wouldn't be much of a point to just replicate the
> functionality of an existing package manager.

That doesn't seem to do the same thing: it doesn't install from a git 
repo, per se, but from local files or directories:

  (package-install-file FILE)

  Install a package from FILE.
  The file can either be a tar file, an Emacs Lisp file, or a
  directory.

What I like to do is to install the package from the git repo as a, 
well, "normal package," i.e. as if it were installed from ELPA.  That's 
how Quelpa works: it produces, e.g. 
"~/.emacs.d/elpa/PACKAGE-VERSION/PACKAGE{,...}.el".  I don't have to 
have a local clone of the repo first.

(Also, the name of the command suggests that it only installs from files 
rather than directories; I didn't even realize it could install from 
directories until now.)

> > In other words, the way package-vc-install currently works leaves me
> > vulnerable to this scenario:
> >
> > 1.  I use package-vc-install to install one of my packages from its
> > local repository directory.
> > 2.  I check out a feature branch of that package to work on a new
> > feature, saving some files but not loading any of the changed code.
> > 3.  I restart Emacs (e.g. maybe I shut down the system and turned it
> > back on the next day).
> > 4.  That work-in-progress feature branch of my package gets loaded
> > into Emacs automatically (which may be entirely broken, being a WIP).
>
> I understand your issue, but anecdotally, I can also give an example
> where I wanted to change some functionality, by M-x find-function'ing
> the source buffer and then loosing the change after upgrading the
> package.

IMHO that seems like a sort of user-error, to leave uncommitted changes 
in a repo that's under the control of a system that doesn't take such 
changes into account when operating on the repo.  IOW, if I install a 
package with command package-FOO, I expect the files it makes to be 
under its purview, not mine; they are not my personal data files, but 
belong to Emacs and its package.el library, the same as if I used "M-x 
package-install".

To put it another way, it seems like a bit of an anti-pattern to develop 
a package that's stored in "~/.emacs.d/elpa"--that directory is supposed 
to be for installed packages' files, and it should be safe to wipe that 
directory out at any time and reinstall packages from their 
sources--after all, "M-x package-delete" shouldn't be wiping out user 
data.  Development on packages should be done on clones stored outside 
of "~/.emacs.d", e.g. in "~/src" or whatever one uses.  IMHO, of 
course--Emacs is all about user freedom--yet I think we should encourage 
the better practices.

> > Whereas if I use Quelpa, it installs the files a package's recipe
> > specifies into the expected location in the elpa/ directory, and that
> > remains independent of whatever I may have checked out in the
> > package's local git directory.  My Emacs configuration and installed
> > packages remain consistent regardless of whatever in-between state I
> > may have left a package's repository in.
> >
> > Philip, would you be willing to consider switching to that model for
> > package-vc-install, or offering it as an option?
>
> Can you describe the interface you are imagining.  From what I
> understand, it should be possible to reproduce what you need by
> combining `package-vc-checkout' and `package-install-file'?

Well, I would expect it to act similarly to Quelpa:

1. Clone the git repo (shallowly, at least by default) to a directory 
(perhaps a temporary one, but at least one stored in the appropriate XDG 
cache directory, outside of user-emacs-directory).

2.  Call package-install-file on that worktree.

3.  The package ends up installed into package-user-dir as if it were 
installed with package-install from ELPA.

Then if the user wants to modify the package, he should either a) use a 
local clone wherever he keeps such projects, or b) configure package-vc 
to clone the repo to such a directory, and then a command could automate 
finding the source files in that directory rather than the ones in 
package-user-dir which are loaded into Emacs.  (IIRC Straight, for 
example, does something like this, but I don't use it myself.)

Do these explanations clarify what I mean?  Let me know if I need to try 
again.  :)

--Adam