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bug#22317: 25.0.50; mh-e: wrong usage of cl-flet
From: |
Katsumi Yamaoka |
Subject: |
bug#22317: 25.0.50; mh-e: wrong usage of cl-flet |
Date: |
Wed, 06 Jan 2016 10:01:23 +0900 |
User-agent: |
Gnus/5.130014 (真 Gnus v0.14) Emacs/25.0.50 (i686-pc-cygwin) |
Hi,
mh-e uses Gnus functions to render MIME messages and uses the
mh-cl-flet macro to modify some of them. Currently mh-e always
loads cl (see mh-acros.el), so both cl-flet and flet are available
and mh-cl-flet will become cl-flet:
,----
| ;; Emacs 24 renamed flet to cl-flet.
| (defalias 'mh-cl-flet
| (if (fboundp 'cl-flet)
| 'cl-flet
| 'flet))
`----
However, cl-flet is quite unlike flet, IIUC. For instance, if
cl-flet is used, the mh-cl-flet code in mh-display-emphasis
,----
| ;; (defun mh-display-emphasis ()
| ;; "Display graphical emphasis."
| ;; (when (and mh-graphical-emphasis-flag (mh-small-show-buffer-p))
| (mh-cl-flet
| ((article-goto-body ())) ; shadow this function to do nothing
| (save-excursion
| (goto-char (point-min))
| (article-emphasize)))
| ;; ))
`----
will be expanded to
,----
| (progn
| (save-excursion
| (goto-char (point-min))
| (article-emphasize)))
`----
whereas if flet is used, it will be expanded to:
,----
| (let* ((vnew (cl-function (lambda nil
| (cl-block article-goto-body))))
| (old (symbol-function 'article-goto-body)))
| (unwind-protect
| (progn
| (fset 'article-goto-body vnew)
| (save-excursion
| (goto-char (point-min))
| (article-emphasize)))
| (fset 'article-goto-body old)))
`----
Note that the former doesn't achieve the original target, i.e.,
article-goto-body is not modified while running article-emphasize.
I don't know how it damages the behavior of mh-e, but I think it
should be fixed anyway. If mh-e keeps loading cl as ever,
mh-cl-flet can be:
(defalias 'mh-cl-flet 'flet)
Otherwise use this complete Emacs-Lisp style flet emulation macro
(a copy of gmm-flet that exists in only the Gnus git master):
--8<---------------cut here---------------start------------->8---
(defmacro mh-cl-flet (bindings &rest body)
"Make temporary overriding function definitions.
This is an analogue of a dynamically scoped `let' that operates on
the function cell of FUNCs rather than their value cell.
\(fn ((FUNC ARGLIST BODY...) ...) FORM...)"
(require 'cl)
(if (fboundp 'cl-letf)
`(cl-letf ,(mapcar (lambda (binding)
`((symbol-function ',(car binding))
(lambda ,@(cdr binding))))
bindings)
,@body)
`(flet ,bindings ,@body)))
(put 'mh-cl-flet 'lisp-indent-function 1)
(put 'mh-cl-flet 'edebug-form-spec
'((&rest (sexp sexp &rest form)) &rest form))
--8<---------------cut here---------------end--------------->8---
I'm not the right person to install it since I'm not a mh-e user,
sorry.
Regards,
- bug#22317: 25.0.50; mh-e: wrong usage of cl-flet,
Katsumi Yamaoka <=