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Re: Lisp hints with VM, BBDB and Personality Crisis
From: |
Jesper Harder |
Subject: |
Re: Lisp hints with VM, BBDB and Personality Crisis |
Date: |
Mon, 15 Sep 2003 04:28:26 +0200 |
User-agent: |
Gnus/5.1003 (Gnus v5.10.3) Emacs/21.3.50 (gnu/linux) |
spam@juliva.com writes:
> I am not an expert in elisp and I was wondering if there is a way to
> shorten the code? Especially, in checking nil variables, I tend to do
> a lot of (unless (eq thingy nil).
You can express it more succinctly as:
(when thingy
...)
which is equivalent to (unless (eq thingy nil) ...).
There's also `null', which is the usual way of testing for a nil
value:
(null thingy) == (eq thingy nil)
Sometimes `not' (which is just another name for `null') might express
your intent better.
> Any other comments are appreciated.
>
> (defun my-check-efriend()
> "Fetch the 'to' address from the e-mail. Look up in bbdb for the given
> address. Look in the note field and check for the string
> 'efriend'. Returns t when that's the case"
The style guideline is to write the first line of a docstring as a
self-contained sentence. Because in some cases -- e.g. when you use
`M-x apropos' -- only the first line is displayed.
> (when (string-match "efriend" note) t)
`when' is redundant here. Just returning the result of
(string-match "efriend" note)
is the conventional way of doing it (the docstring should then say
"Return non-nil when ...", of course).