(defmacro mm-with-unibyte-current-buffer (&rest forms)
"Evaluate FORMS with current buffer temporarily made unibyte.
-Also bind the default-value of `enable-multibyte-characters' to nil.
-Equivalent to `progn' in XEmacs
-
-NOTE: Use this macro with caution in multibyte buffers (it is not
-worth using this macro in unibyte buffers of course). Use of
-`(set-buffer-multibyte t)', which is run finally, is generally
-harmful since it is likely to modify existing data in the buffer.
-For instance, it converts \"\\300\\255\" into \"\\255\" in
-Emacs 23 (unicode)."
+Equivalent to `progn' in XEmacs.
+
+Note: We recommend not using this macro any more; there should be
+better ways to do a similar thing. The previous version of this macro
+bound the default value of `enable-multibyte-characters' to nil while
+evaluating FORMS but it is no longer done. So, some programs assuming
+it if any may malfunction."
(if (featurep 'xemacs)
`(progn ,@forms)
- ;; FIXME: (default-value 'enable-multibyte-characters) is read-only
- ;; so let-binding it is wrong. The right fix is to not use this
- ;; macro at all any more, since it's been ill-defined from the start.
- (let ((multibyte (make-symbol "multibyte"))
- (buffer (make-symbol "buffer")))
- `(if mm-emacs-mule
- (let ((,multibyte enable-multibyte-characters)
- (,buffer (current-buffer)))
- (unwind-protect
- (letf (((default-value 'enable-multibyte-characters) nil))
- (set-buffer-multibyte nil)
- ,@forms)
- (set-buffer ,buffer)
- (set-buffer-multibyte ,multibyte)))
- (letf (((default-value 'enable-multibyte-characters) nil))
- ,@forms)))))
+ (let ((multibyte (make-symbol "multibyte")))
+ `(let ((,multibyte enable-multibyte-characters))
+ (when ,multibyte
+ (set-buffer-multibyte nil))
+ (prog1
+ (progn ,@forms)
+ (when ,multibyte
+ (set-buffer-multibyte t)))))))
(put 'mm-with-unibyte-current-buffer 'lisp-indent-function 0)
(put 'mm-with-unibyte-current-buffer 'edebug-form-spec '(body))