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From: Les Harris <les@lesharris.com>
To: help-gnu-emacs@gnu.org
Subject: Concern around use of eval
Date: Wed, 18 Mar 2015 23:53:51 -0700	[thread overview]
Message-ID: <medrpv$a2h$1@ger.gmane.org> (raw)

I have a situation where I want to generate a bunch of nearly identical
predicate functions. Previously I had just manually defined these things
one by one but was never happy with such an obvious inefficiency (or
maintaining it). Tonight I decided I'd fix this and whacked them and
implemented a way of doing it where I can iterate over a list containing
labels and define these predicate functions using those labels:

,----
| (defvar lh/labels '("label1" "label2" "label3"))
| 
| (defmacro lh/gen-predicate (label)
|   `(defun ,(intern (concat "lh/" label "-p")) ()
|             (member ,label *lh/system-label-store*)))
| 
| (defun lh/define-predicates ()
|   (dolist (label lh/labels)
|     (eval `(lh/gen-predicate ,label))))
| (lh/define-predicates)
`----

Now this all works fine and I get my auto-generated predicates, so
success. My question/concern/niggle is around the use of (eval) in
lh/define-predicates. If I don't put eval in there then the defun the
macro evaluates into never gets evaluated itself. Stylistically, is
there a better way to do this or am I just being weird about (eval) and
should just get over it?

-- 
Do they only stand
By ignorance, is that their happy state,
The proof of their obedience and their faith?




             reply	other threads:[~2015-03-19  6:53 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-19  6:53 Les Harris [this message]
2015-03-19  8:00 ` Concern around use of eval Tassilo Horn
     [not found] ` <mailman.2302.1426752018.31049.help-gnu-emacs@gnu.org>
2015-03-19  8:12   ` Joost Kremers
2015-03-19  8:31     ` Tassilo Horn
     [not found]     ` <mailman.2305.1426753885.31049.help-gnu-emacs@gnu.org>
2015-03-20 19:54       ` Joost Kremers
2015-03-19 14:07 ` Stefan Monnier
2015-03-20 15:17   ` Thierry Volpiatto
2015-03-20 17:19     ` Bug in Elisp font-locking (was: Concern around use of eval) Tassilo Horn
2015-03-20 17:31       ` Bug in Elisp font-locking Stefan Monnier
2015-03-20 17:43         ` Drew Adams
2015-03-20 18:47         ` Tassilo Horn
2015-03-20 20:38           ` Stefan Monnier
2015-03-20 22:45             ` Tassilo Horn
2015-03-21  2:33               ` Stefan Monnier

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