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Re: elisp newbie: simplifying from cl structures?
From: |
Pascal J. Bourguignon |
Subject: |
Re: elisp newbie: simplifying from cl structures? |
Date: |
Sun, 08 Feb 2015 04:37:38 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) |
torys.anderson@gmail.com (Tory S. Anderson) writes:
> Thanks for helping me straighten the code out and gain better
> understanding cl-tools and structure; it loads and mostly
> works. Thanks!
>
> (defun change-smtp ()
> "Change the SMTP server according to the current from line."
> (save-excursion
> (cl-loop with from = (save-restriction
> (message-narrow-to-headers)
> (message-fetch-field "from"))
> for (address server port) in smtp-accounts
> do (if (string-match address from)
> (return (funcall 'set-smtp server port address))
> (message "Failed to match %s with %s" address from))
> finally (error "Cannot infer SMTP information."))))
>
> (add-hook 'message-send-mail-hook 'change-smtp)
Ok, but now, you should consider that this functions is performing
several tasks of different order: some parsing of a message is done, as
well as some searching for smtp configuration, and some setting of smtp
configuration. That's a lot for a single function.
It would be better if you split it as follow, which would give you two
nice reusable functions, and makes change-smtp clearer:
(defun message-from-field ()
"Find the from field in the current buffer that must contain a message."
(save-excursion
(save-restriction
(message-narrow-to-headers)
(message-fetch-field "from"))))
(defun find-smtp-account (address accounts)
"Find the first account in `accounts' whose address matches `address'."
(find from accounts :key (function first)
:test (lambda (from address)
(string-match address from))))
(defun change-smtp ()
(let ((from (message-from-field)))
(destructuring-bind (address server port) (find-smtp-account from
smtp-accounts)
(if address
(funcall 'set-smtp server port address)
(error "Cannot not infer SMTP information")))))
--
__Pascal Bourguignon__ http://www.informatimago.com/
“The factory of the future will have only two employees, a man and a
dog. The man will be there to feed the dog. The dog will be there to
keep the man from touching the equipment.” -- Carl Bass CEO Autodesk