[Emacs-diffs] package-archive-priorities ab9a878: Package archives now have priorities.

[Jorgen Schäfer]

branch: package-archive-priorities
commit ab9a878fd8bbfa7b2e1195d346feff70d1e8889a
Author: Jorgen Schaefer <address@hidden>
Commit: Jorgen Schaefer <address@hidden>

    Package archives now have priorities.
    
    When installing packages by name, only packages from archives with
    the highest priority are considered, before versions are compared.
    
    This solves the "MELPA problem", where MELPA assigns date-based
    version numbers to packages which override all other archives.
    Giving MELPA a lower priority means packages are installed from
    MELPA only when the package is not available from other archives.
    
    This can be overridden manually by the user.
---
 lisp/emacs-lisp/package.el     |   45 ++++++++++++++++++++++++++++++++++++++-
 test/automated/package-test.el |   17 +++++++++++++++
 2 files changed, 60 insertions(+), 2 deletions(-)

diff --git a/lisp/emacs-lisp/package.el b/lisp/emacs-lisp/package.el
index 4e5c397..2030482 100644
--- a/lisp/emacs-lisp/package.el
+++ b/lisp/emacs-lisp/package.el
@@ -228,6 +228,33 @@ a package can run arbitrary code."
   :group 'package
   :version "24.1")
 
+(defcustom package-archive-default-priority 500
+  "The default priority for archives.
+
+This is used if the archive is not found in
+`package-archive-priorities'."
+  :type 'integer
+  :risky t
+  :group 'package
+  :version "25.1")
+
+(defcustom package-archive-priorities nil
+  "An alist of priorities for packages.
+
+Each element has the form (ARCHIVE-ID . PRIORITY).
+
+When installing packages, the package with the highest version
+number from the archive with the highest priority is
+selected. When higher versions are available from archives with
+lower priorities, the user has to select those manually.
+
+Archives not in this list have the priority given in
+`package-archive-default-priority'."
+  :type 'integer
+  :risky t
+  :group 'package
+  :version "25.1")
+
 (defcustom package-pinned-packages nil
   "An alist of packages that are pinned to specific archives.
 This can be useful if you have multiple package archives enabled,
@@ -1063,6 +1090,7 @@ Also, add the originating archive to the `package-desc' 
structure."
                         ;; Older archive-contents files have only 4
                         ;; elements here.
                         (package--ac-desc-extras (cdr package)))))
+         (archive-priority (package-archive-priority archive))
          (existing-packages (assq name package-archive-contents))
          (pinned-to-archive (assoc name package-pinned-packages)))
     (cond
@@ -1075,8 +1103,12 @@ Also, add the originating archive to the `package-desc' 
structure."
      (t
       (while
           (if (and (cdr existing-packages)
-                   (version-list-<
-                    version (package-desc-version (cadr existing-packages))))
+                   (or (< archive-priority
+                          (package-archive-priority
+                           (package-desc-archive (cadr existing-packages))))
+                       (version-list-<
+                        version
+                        (package-desc-version (cadr existing-packages)))))
               (setq existing-packages (cdr existing-packages))
             (push pkg-desc (cdr existing-packages))
             nil))))))
@@ -1268,6 +1300,15 @@ The file can either be a tar file or an Emacs Lisp file."
   "Return the archive containing the package NAME."
   (cdr (assoc (package-desc-archive desc) package-archives)))
 
+(defun package-archive-priority (archive)
+  "Return the priority of ARCHIVE.
+
+The archive priorities are specified in
+`package-archive-priorities' and
+`package-archive-default-priority'."
+  (or (cdr (assoc archive package-archive-priorities))
+      package-archive-default-priority))
+
 (defun package--download-one-archive (archive file)
   "Retrieve an archive file FILE from ARCHIVE, and cache it.
 ARCHIVE should be a cons cell of the form (NAME . LOCATION),
diff --git a/test/automated/package-test.el b/test/automated/package-test.el
index 6e7994a..2a337fb 100644
--- a/test/automated/package-test.el
+++ b/test/automated/package-test.el
@@ -230,6 +230,23 @@ Must called from within a `tar-mode' buffer."
     (package-refresh-contents)
     (package-install 'simple-single)))
 
+(ert-deftest package-test-install-prioritized ()
+  "Install a lower version from a higher-prioritized archive."
+  (with-package-test ()
+    (let* ((newer-version (expand-file-name "data/package/newer-versions"
+                                            package-test-file-dir))
+           (package-archives `(("older" . ,package-test-data-dir)
+                               ("newer" . ,newer-version)))
+           (package-archive-priorities '(("newer" . 100))))
+
+      (package-initialize)
+      (package-refresh-contents)
+      (package-install 'simple-single)
+
+      (let ((installed (cdr (assq 'simple-single package-alist))))
+        (should (version-list-= '(1 3)
+                                (package-desc-version installed)))))))
+
 (ert-deftest package-test-install-multifile ()
   "Check properties of the installed multi-file package."
   (with-package-test (:basedir "data/package" :install '(multi-file))