Date: Wed, 18 Jan 2012 14:21:47 -0500
From: Austin Clements <amdragon@MIT.EDU>
To: Mark Walters <markwalters1009@gmail.com>
Subject: Re: [PATCH v3] Make buttons for attachments allow viewing as well as
	saving
Message-ID: <20120118192147.GF16740@mit.edu>
References: <87lip5rj43.fsf@qmul.ac.uk>
	<1326843886-18387-1-git-send-email-markwalters1009@gmail.com>
	<20120117235318.GZ16740@mit.edu> <87ipk9rgg9.fsf@qmul.ac.uk>
	<20120118012539.GA16740@mit.edu> <87fwfdqoev.fsf@qmul.ac.uk>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <87fwfdqoev.fsf@qmul.ac.uk>
User-Agent: Mutt/1.5.21 (2010-09-15)
Cc: notmuch@notmuchmail.org
Precedence: list

Quoth Mark Walters on Jan 18 at 10:46 am:
> 
> > > +(defun notmuch-show-view-part (message-id nth &optional filename content-type )
> > > +  (notmuch-with-temp-part-buffer message-id nth
> > > +    ;; set mm-inlined-types to nil to force an external viewer
> > > +    (let ((handle (mm-make-handle (current-buffer) (list content-type)))
> > > +         (mm-inlined-types nil))
> > > +      ;; We override mm-save-part as notmuch-show-save-part is better
> > > +      ;; since it offers the filename
> > > +      (flet ((mm-save-part (&rest args) (ignore)))
> > > +           (or (mm-display-part handle)
> > > +               (notmuch-show-save-part message-id nth filename content-type))))))
> > > 
> > > Is that a reasonable solution? 
> > 
> > It's *probably* safe to depend on the result of mm-display-part, but
> > you can avoid the question altogether by simply calling
> > notmuch-show-save-part from your flet mm-save-part.  E.g.,
> > 
> > (flet ((mm-save-part (&rest args) (notmuch-show-save-part 
> >                                    message-id nth filename content-type)))
> >   (mm-display-part handle))
> 
> Unfortunately that does not work since mm-display-part has a local
> variable "filename".  I could copy the variables to some notmuch
> prefixed variables but maybe there is some obvious "quoting" to avoid
> the problem? (I can't easily check now as the gnu site is closed for the
> day.)

Arrrg, dynamic scoping.  Well, you can

;; Lexically bind everything we need in mm-save-part to prevent
;; potential dynamic shadowing.
(lexical-let ((message-id message-id)
              (nth nth)
              (filename filename)
              (content-type content-type))
  (flet ((mm-save-part (&rest args) (notmuch-show-save-part 
                                     message-id nth filename content-type)))
    (mm-display-part handle)))

Or you could just, y'know, do what were doing.