unload features before installing packages with :ensure

[shackra]

I'm looking to this feature for cases like org-mode that advice you to don't load any org file to avoid issues when updating to 8.x, I know that you can unload features, someone else in the Emacs IRC channel suggested me to use unintern.

I guess that for this feature, simply allow the user to run any elisp code before :ensure does it's job if, and only if, a package does not exists and need to be installed.

[Fuco1]

You realize that you upgrade once and then it's over? You are creating a problem for you that does not exist. Simply run emacs -q, update, and then have fun with your new org version.

[shackra]

@Fuco1 I know I can do that, but I want something that don't requires me to do that.

[YoungFrog]

IIUC, either the package exists and :ensure won't do anything (it
doesn't check for upgrades), or it does not exist and there is no
problem. What am I missing ?

[shackra]

@YoungFrog the package exists, it comes with Emacs. But the org-mode project says that if you are going to update org-mode, you better don't have it loaded. This directive cannot be followed if you configuration is loaded from a org file.

[npostavs]

run any elisp code before :ensure does it's job if, and only if, a package does not exists
...
the package exists, it comes with Emacs.

So this feature will not help you.

[shackra]

Why not, @npostavs?

[npostavs]

org is already installed so :ensure will not do anything. Your proposed before-ensure-hook will likewise not run.

[shackra]

@npostavs I can confirm you that it is not the case.

[thomasf]

yeah, thats not the case.. However, when you upgrade the package next time it won't happen.. I also believe that that this is too much of a created problem with undefined behaviour for things such as package upgrades which might for instance be done without use-pacakge even loaded..

If this feature should exists it should probably live in package.el and not use-package.

[npostavs]

I can confirm you that it is not the case.

Huh? You asked "to run ... elisp code ... if, and only if, a package does not exist..." and then said "the package exists, it comes with Emacs".

Furthermore, use-package-ensure-elpa:

(defun use-package-ensure-elpa (package)
  (when (not (package-installed-p package))
    (package-install package)))

In my emacs 24.3 without upgrading org whatsoever:
(package-installed-p 'org) => t

yeah, thats not the case.. However, when you upgrade the package next time it won't happen.

:ensure doesn't check the "upgraded" status, it checks the installed status. What am I missing?

[thomasf]

When I start emacs (24.3.94) using emacs -Q and then list-packages the org package is not listed for me,,., I guess package.el would install it for me if it was "ensured"..

If you are using org-modes own package.el repo it gets even stranger since you as a user might want the org-plus-contrib package while other packages probably depends on the one only named org which basically means that you will get a double org mode installs as well... Here i would prefer if the org-plus-contrib package actually would depend on the org one to lessen the risk of problems,

My opinion is that all these things even more strongly suggests that the problem, if there is one lies in one or more of:

• emacs own default packaged org (not registered)
• package.el (lack of package specific upgrade routines)
• org-modes own package.el repository (multiple packages providing the same thing by different names, could also be solved by improving package.el to have meta packages)

And not anything use-package should fix.

[thomasf]

@shackra I suggest that if you really want this you should implement it in your own init.el by adding advices to some package.el functions. And/or take it up on the emacs mailing lists.

Also, as a side note: I always restart my emacs instances after package upgrades, there are so many potential problems arising from that situation that some things are unloaded and others arent if you have lots of packages installed... I don't know if it ever has caused any problems but I won't take that risk.

[shackra]

@npostavs really, "ensure" will upgrade org, I'm not kidding since I did a test.

@thomasf well, you are right, an update routine seems to be missing in package.el for packages like org.

[npostavs]

When I start emacs (24.3.94) using emacs -Q and then list-packages the org package is not listed for me,,., I guess package.el would install it for me if it was "ensured"..

Hmm, the builtin version is not listed (even though other builtin packages are) but (package-installed-p 'org) still returns non-nil.

really, "ensure" will upgrade org, I'm not kidding since I did a test.

Interesting, I also did a test and got the opposite result. Either we have different Emacsen, or different tests. I tried with Emacs versions 24.3.3, and 24.3.94.1 with the following init.el:

(add-to-list 'load-path "/home/npostavs/src/use-package")

(package-initialize t)

(require 'use-package)
(use-package org
  :ensure t)

[shackra]

@npostavs maybe if you tried this:

(add-to-list 'load-path "/home/npostavs/src/use-package")
(package-initialize t)

(setf package-archives (list (quote ("gnu" . "http://elpa.gnu.org/packages/"))
                               (quote ("marmalade" . "http://marmalade-repo.org/packages/"))
                               (quote ("melpa" . "http://melpa.milkbox.net/packages/"))
                               (quote ("org" . "http://orgmode.org/elpa/"))))
(package-refresh-contents)
(require 'use-package)
(use-package org
  :ensure t)