Provide generic framework for calling message-next

[Ryan Kavanagh]

 affects vm
 importance wishlist

It would be nice to have a generic framework to call "message-next"
after a certain command (e.g. reading, deleting, marking unread, etc.),
similar to the current vm-move-after-{reading,deleting} variables.
Presumably this could be configured via an "alist" of some sort, e.g.

(setq vm-post-commands
    '((vm-delete-message . '(vm-next-message))
      (vm-mark-message-read . '(vm-next-message))
      (vm-mark-message-unread . '(vm-previous-message))
      (vm-blah . '(vm-cmd1 vm-cmd2 ... vm-cmdN))))

where for each time a command is called (this can presumably be limited
to a reasonable subset like reading, deleting, unreading, marking, etc.
in implementation), its associated "post-commands", if any, are
sequentially called. In the above example, vm-next-message would be
called after deleting and reading a message, but vm-previous-message
would be called after unreading a message.

This would render vm-move-after-reading and vm-move-after-deleting
obsolete, but would be cleaner in my opinion than having to submit a
vm-move-after-XYZ patch for each command I'd like to move after :)

I'm not yet familiar with lisp, but if someone would like to guide me in
implementing this, I'll gladly do the legwork.

--
|_)|_/ Ryan Kavanagh | Debian Developer
| \| \ http://ryanak.ca/ | GPG Key 4A11C97A

[Uday Reddy (reddyuday)]

Hi Ryan, What other operations would require auto-movement commands? What
would be the rationale for auto-movement?

In the case of delete, the rationale is clear. Since we are getting rid of
the current message, we presumably want to move to another one. For
vm-flag-message-read, the motivation is similar. We are getting rid of it
from the "unread messages" pool. So, presumably we want to move to another
unread message (though I discovered that I do not always want this). Why do
you need auto-movement for other commands?

[Ryan Kavanagh (ryanakca)]

Hi Uday,

On Mon, Mar 11, 2013 at 06:38:06PM -0000, Uday Reddy wrote:
> Hi Ryan, What other operations would require auto-movement commands?

Off the top of my head:
 * mark a message read/unread
 * mark a message delete/undelete
 * mark a message flag/unflag
 * mark/unmark a message (vm-mark-message)

> What would be the rationale for auto-movement?

The ability to save a vm-next-message when going through a mailbox and
applying a series of commands. That's to say, if I'm going through a
mailbox to flag important messages, having vm call `vm-next-message'
automatically for me saves me from having to do so. Thus, when going
through n messages, I only need n keystrokes, rather than n+k, where k
is the number of operations (flag/unflag/delete/etc) I perform.
Similarly for the other operations.

Best wishes,
Ryan

--
|_)|_/ Ryan Kavanagh | Debian Developer
| \| \ http://ryanak.ca/ | GPG Key 4A11C97A