emacs-lisp/package.el (package--user-selected-p): New function.

Populates `package-selected-packages' if necessary, and then checks if
symbol PKG is contained in it.

lisp/ChangeLog

@@ -2,6 +2,18 @@
 
 	* emacs-lisp/package.el (package-delete): Document NOSAVE.
 	(package--get-deps): delete-dups when ONLY is nil.
+	(package-autoremove): Warn the user if `package-selected-packages'
+	is empty.
+
+	(package--user-selected-p): New function.
+	(package-delete, package-install, package-install-from-buffer):
+	Use it
+	(package-selected-packages): Mention it.
+
+	(package-initialize): Don't populate `package-selected-packages'.
+	(package-install-user-selected-packages, package-autoremove):
+	Special handling for empty `package-selected-packages'.
+	(package-install): Fix when PKG is a package-desc.
 
 2015-02-03  Thierry Volpiatto  <thierry.volpiatto@gmail.com>
 

lisp/emacs-lisp/package.el

@@ -340,7 +340,11 @@ when installing a new package.
 This variable will be used by `package-autoremove' to decide
 which packages are no more needed.
 You can use it to (re)install packages on other machines
-by running `package-user-selected-packages-install'."
+by running `package-user-selected-packages-install'.
+
+To check if a package is contained in this list here, use
+`package--user-selected-p', as it may populate the variable with
+a sane initial value."
   :group 'package
   :type '(repeat symbol))
 
@@ -1189,6 +1193,17 @@ number."
                nil))
       alist)))
 
+(defun package--user-selected-p (pkg)
+  "Return non-nil if PKG is a package was installed by the user.
+PKG is a package name.
+This looks into `package-selected-packages', populating it first
+if it is still empty."
+  (unless (consp package-selected-packages)
+    (customize-save-variable
+     'package-selected-packages
+     (setq package-selected-packages (package--find-non-dependencies))))
+  (memq pkg package-selected-packages))
+
 (defun package-download-transaction (packages)
   "Download and install all the packages in PACKAGES.
 PACKAGES should be a list of package-desc.
@@ -1222,9 +1237,12 @@ to `package-selected-packages'."
                                   package-archive-contents))
                     nil t))
            t)))
-  (when (and mark-selected (not (memq pkg package-selected-packages)))
-    (customize-save-variable 'package-selected-packages
-                            (cons pkg package-selected-packages)))
+  (let ((name (if (package-desc-p pkg)
+                  (package-desc-name pkg)
+                pkg)))
+    (when (and mark-selected (not (package--user-selected-p name)))
+      (customize-save-variable 'package-selected-packages
+                               (cons name package-selected-packages))))
   (package-download-transaction
    (if (package-desc-p pkg)
        (package-compute-transaction (list pkg)
@@ -1239,8 +1257,7 @@ to `package-selected-packages'."
                               "Reinstall package: "
                               (mapcar #'symbol-name
                                       (mapcar #'car package-alist))))))
-  (package-delete (cadr (assq pkg package-alist)) 'force
-                  (memq pkg package-selected-packages))
+  (package-delete (cadr (assq pkg package-alist)) 'force 'nosave)
   (package-install pkg))
 
 (defun package-strip-rcs-id (str)
@@ -1402,10 +1419,9 @@ Downloads and installs required packages as needed."
       (package-download-transaction transaction))
     ;; Install the package itself.
     (package-unpack pkg-desc)
-    (unless (memq name package-selected-packages)
-      (push name package-selected-packages)
+    (unless (package--user-selected-p name)
       (customize-save-variable 'package-selected-packages
-                               package-selected-packages))
+                               (cons name package-selected-packages)))
     pkg-desc))
 
 ;;;###autoload
@@ -1443,17 +1459,22 @@ The file can either be a tar file or an Emacs Lisp file."
   "Ensure packages in `package-selected-packages' are installed.
 If some packages are not installed propose to install them."
   (interactive)
-  (cl-loop for p in package-selected-packages
-           unless (package-installed-p p)
-           collect p into lst
-           finally
-           (if lst
-               (when (y-or-n-p
-                      (format "%s packages will be installed:\n%s, proceed?"
-                              (length lst)
-                              (mapconcat #'symbol-name lst ", ")))
-                 (mapc #'package-install lst))
-             (message "All your packages are already installed"))))
+  ;; We don't need to populate `package-selected-packages' before
+  ;; using here, because the outcome is the same either way (nothing
+  ;; gets installed).
+  (if (not package-selected-packages)
+      (message "`package-selected-packages' is empty, nothing to install")
+    (cl-loop for p in package-selected-packages
+             unless (package-installed-p p)
+             collect p into lst
+             finally
+             (if lst
+                 (when (y-or-n-p
+                        (format "%s packages will be installed:\n%s, proceed?"
+                          (length lst)
+                          (mapconcat #'symbol-name lst ", ")))
+                   (mapc #'package-install lst))
+               (message "All your packages are already installed")))))
 
 (defun package--used-elsewhere-p (pkg-desc &optional pkg-list)
   "Non-nil if PKG-DESC is a dependency of a package in PKG-LIST.
@@ -1509,8 +1530,8 @@ If NOSAVE is non-nil, the package is not removed from
              (unless (cdr pkgs)
                (setq package-alist (delq pkgs package-alist))))
            ;; Update package-selected-packages.
-           (when (and (memq name package-selected-packages)
-                      (null nosave))
+           (when (and (null nosave)
+                      (package--user-selected-p name))
              (customize-save-variable
               'package-selected-packages (remove name package-selected-packages)))
            (message "Package `%s' deleted." (package-desc-full-name pkg-desc))))))
@@ -1523,21 +1544,28 @@ Packages that are no more needed by other packages in
 `package-selected-packages' and their dependencies
 will be deleted."
   (interactive)
-  (let ((needed (cl-loop for p in package-selected-packages
-                      if (assq p package-alist)
-                      append (package--get-deps p))))
-    (cl-loop for p in (mapcar #'car package-alist)
-             unless (or (memq p needed)
-                        (memq p package-selected-packages))
-             collect p into lst
-             finally (if lst
-                         (when (y-or-n-p (format "%s packages will be deleted:\n%s, proceed? "
-                                                 (length lst)
-                                                 (mapconcat #'symbol-name lst ", ")))
-                           (mapc (lambda (p)
-                                   (package-delete (cadr (assq p package-alist)) t))
-                                 lst))
-                       (message "Nothing to autoremove")))))
+  ;; If `package-selected-packages' is nil, it would make no sense to
+  ;; try to populate it here, because then `package-autoremove' will
+  ;; do absolutely nothing.
+  (when (or package-selected-packages
+            (yes-or-no-p
+             "`package-selected-packages' is empty! Really remove ALL packages? "))
+    (let ((needed (cl-loop for p in package-selected-packages
+                           if (assq p package-alist)
+                           ;; `p' and its dependencies are needed.
+                           append (cons p (package--get-deps p)))))
+      (cl-loop for p in (mapcar #'car package-alist)
+               unless (memq p needed)
+               collect p into lst
+               finally (if lst
+                           (when (y-or-n-p
+                                  (format "%s packages will be deleted:\n%s, proceed? "
+                                          (length lst)
+                                          (mapconcat #'symbol-name lst ", ")))
+                             (mapc (lambda (p)
+                                     (package-delete (cadr (assq p package-alist)) t))
+                               lst))
+                         (message "Nothing to autoremove"))))))
 
 (defun package-archive-base (desc)
   "Return the archive containing the package NAME."
@@ -1663,9 +1691,6 @@ If optional arg NO-ACTIVATE is non-nil, don't activate packages."
   (unless no-activate
     (dolist (elt package-alist)
       (package-activate (car elt))))
-  (when (and package-alist (not package-selected-packages))
-    (customize-save-variable 'package-selected-packages
-                             (package--find-non-dependencies)))
   (setq package--initialized t))