-;; Because the `partial-completion-mode' option is defined before the
-;; `partial-completion-mode' command and its callee, we give the former a
-;; default `:initialize' keyword value. Otherwise, the `:set' keyword value
-;; would be called to initialise the variable value, and that would call the
-;; as-yet undefined `partial-completion-mode' function.
-;; Since the default `:initialize' keyword value (obviously) does not turn on
-;; Partial Completion Mode, we do that here, once the `partial-completion-mode'
-;; function and its callee are defined.
-(when partial-completion-mode
- (partial-completion-mode t))
+;;;###autoload
+(define-minor-mode partial-completion-mode
+ "Toggle Partial Completion mode.
+With prefix ARG, turn Partial Completion mode on if ARG is positive.
+
+When Partial Completion mode is enabled, TAB (or M-TAB if `PC-meta-flag' is
+nil) is enhanced so that if some string is divided into words and each word is
+delimited by a character in `PC-word-delimiters', partial words are completed
+as much as possible and `*' characters are treated likewise in file names.
+
+For example, M-x p-c-m expands to M-x partial-completion-mode since no other
+command begins with that sequence of characters, and
+\\[find-file] f_b.c TAB might complete to foo_bar.c if that file existed and no
+other file in that directory begin with that sequence of characters.
+
+Unless `PC-disable-includes' is non-nil, the `<...>' sequence is interpreted
+specially in \\[find-file]. For example,
+\\[find-file] <sys/time.h> RET finds the file `/usr/include/sys/time.h'.
+See also the variable `PC-include-file-path'."
+ :global t :group 'partial-completion
+ ;; Deal with key bindings...
+ (PC-bindings partial-completion-mode)
+ ;; Deal with include file feature...
+ (cond ((not partial-completion-mode)
+ (remove-hook 'find-file-not-found-hooks 'PC-look-for-include-file))
+ ((not PC-disable-includes)
+ (add-hook 'find-file-not-found-hooks 'PC-look-for-include-file)))
+ ;; ... with some underhand redefining.
+ (cond ((and (not partial-completion-mode)
+ (functionp PC-old-read-file-name-internal))
+ (fset 'read-file-name-internal PC-old-read-file-name-internal))
+ ((and (not PC-disable-includes) (not PC-old-read-file-name-internal))
+ (setq PC-old-read-file-name-internal
+ (symbol-function 'read-file-name-internal))
+ (fset 'read-file-name-internal
+ 'PC-read-include-file-name-internal)))
+ (when (and partial-completion-mode (null PC-env-vars-alist))
+ (setq PC-env-vars-alist
+ (mapcar (lambda (string)
+ (let ((d (string-match "=" string)))
+ (cons (concat "$" (substring string 0 d))
+ (and d (substring string (1+ d))))))
+ process-environment))))
+