*** empty log message ***

[bpt/emacs.git] / lisp / loadhist.el

diff --git a/lisp/loadhist.el b/lisp/loadhist.el
index 733129f..76ef87e 100644 (file)
--- a/lisp/loadhist.el
+++ b/lisp/loadhist.el
@@ -51,9 +51,26 @@ a buffer with no associated file, or an `eval-region', return nil."
       (error "%S is not a currently loaded feature" feature)
     (car (feature-symbols feature))))
 
+(defun file-loadhist-lookup (file)
+  "Return the `load-history' element for FILE."
+  ;; First look for FILE as given.
+  (let ((symbols (assoc file load-history)))
+    ;; Try converting a library name to an absolute file name.
+    (and (null symbols)
+        (let ((absname (find-library-name file)))
+          (if (not (equal absname file))
+              (setq symbols (cdr (assoc absname load-history))))))
+    ;; Try converting an absolute file name to a library name.
+    (and (null symbols) (string-match "[.]el\\'" file)
+        (let ((libname (file-name-nondirectory file)))
+          (string-match "[.]el\\'" libname)
+          (setq libname (substring libname 0 (match-beginning 0)))
+          (setq symbols (cdr (assoc libname load-history)))))
+    symbols))
+
 (defun file-provides (file)
   "Return the list of features provided by FILE."
-  (let ((symbols (cdr (assoc file load-history)))
+  (let ((symbols (file-loadhist-lookup file))
        provides)
     (mapc (lambda (x)
            (if (and (consp x) (eq (car x) 'provide))
@@ -63,7 +80,7 @@ a buffer with no associated file, or an `eval-region', return nil."
 
 (defun file-requires (file)
   "Return the list of features required by FILE."
-  (let ((symbols (cdr (assoc file load-history)))
+  (let ((symbols (file-loadhist-lookup file))
        requires)
     (mapc (lambda (x)
            (if (and (consp x) (eq (car x) 'require))
@@ -116,11 +133,27 @@ These are symbols with hook-type values whose names don't end in
 `-hook' or `-hooks', from which `unload-feature' tries to remove
 pertinent symbols.")
 
+(defvar unload-hook-features-list nil
+  "List of features of the package being unloaded.
+
+This is meant to be used by FEATURE-unload-hook hooks, see the
+documentation of `unload-feature' for details.")
+
 ;;;###autoload
 (defun unload-feature (feature &optional force)
   "Unload the library that provided FEATURE, restoring all its autoloads.
 If the feature is required by any other loaded code, and prefix arg FORCE
-is nil, raise an error."
+is nil, raise an error.
+
+This function tries to undo modifications made by the package to
+hooks.  Packages may define a hook FEATURE-unload-hook that is called
+instead of the normal heuristics for doing this.  Such a hook should
+undo all the relevant global state changes that may have been made by
+loading the package or executing functions in it.  It has access to
+the package's feature list (before anything is unbound) in the
+variable `unload-hook-features-list' and could remove features from it
+in the event that the package has done something normally-ill-advised,
+such as redefining an Emacs function."
   (interactive (list (read-feature "Feature: ") current-prefix-arg))
   (if (not (featurep feature))
       (error "%s is not a currently loaded feature" (symbol-name feature)))
@@ -130,8 +163,8 @@ is nil, raise an error."
        (if dependents
            (error "Loaded libraries %s depend on %s"
                   (prin1-to-string dependents) file))))
-  (let* ((flist (feature-symbols feature))
-         (file (car flist))
+  (let* ((unload-hook-features-list (feature-symbols feature))
+         (file (car unload-hook-features-list))
          (unload-hook (intern-soft (concat (symbol-name feature)
                                            "-unload-hook"))))
     ;; Try to avoid losing badly when hooks installed in critical
@@ -155,10 +188,10 @@ is nil, raise an error."
                       (string-match "-hooks?\\'" (symbol-name x)))
                  (and (boundp x)       ; Known abnormal hooks etc.
                       (memq x unload-feature-special-hooks)))
-            (dolist (y (cdr flist))
+            (dolist (y (cdr unload-hook-features-list))
               (remove-hook x y))))))
     (if (fboundp 'elp-restore-function)        ; remove ELP stuff first
-       (dolist (elt (cdr flist))
+       (dolist (elt (cdr unload-hook-features-list))
          (if (symbolp elt)
              (elp-restore-function elt))))
     (mapc
@@ -183,7 +216,7 @@ is nil, raise an error."
                (fmakunbound x)
                (let ((aload (get x 'autoload)))
                  (if aload (fset x (cons 'autoload aload))))))))
-     (cdr flist))
+     (cdr unload-hook-features-list))
     ;; Delete the load-history element for this file.
     (let ((elt (assoc file load-history)))
       (setq load-history (delq elt load-history)))))