Merged from miles@gnu.org--gnu-2005 (patch 149-151, 629-641)

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

diff --git a/lisp/subr.el b/lisp/subr.el
index 944f73b..5613940 100644 (file)
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -1309,6 +1309,34 @@ definition only or variable definition only.
        (setq files (cdr files)))
       file)))
 
+;;;###autoload
+(defun locate-library (library &optional nosuffix path interactive-call)
+  "Show the precise file name of Emacs library LIBRARY.
+This command searches the directories in `load-path' like `\\[load-library]'
+to find the file that `\\[load-library] RET LIBRARY RET' would load.
+Optional second arg NOSUFFIX non-nil means don't add suffixes `load-suffixes'
+to the specified name LIBRARY.
+
+If the optional third arg PATH is specified, that list of directories
+is used instead of `load-path'.
+
+When called from a program, the file name is normaly returned as a
+string.  When run interactively, the argument INTERACTIVE-CALL is t,
+and the file name is displayed in the echo area."
+  (interactive (list (completing-read "Locate library: "
+                                     'locate-file-completion
+                                     (cons load-path load-suffixes))
+                    nil nil
+                    t))
+  (let ((file (locate-file library
+                          (or path load-path)
+                          (append (unless nosuffix load-suffixes) '("")))))
+    (if interactive-call
+       (if file
+           (message "Library is file %s" (abbreviate-file-name file))
+         (message "No library %s in search path" library)))
+    file))
+
 \f
 ;;;; Specifying things to do later.