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From: Tassilo Horn <tsdh@gnu.org>
To: help-gnu-emacs@gnu.org
Subject: Re: Concern around use of eval
Date: Thu, 19 Mar 2015 09:31:17 +0100	[thread overview]
Message-ID: <87d2458k2y.fsf@gnu.org> (raw)
In-Reply-To: <slrnmgl16k.6n4.joost.m.kremers@j.kremers4.news.arnhem.chello.nl> (Joost Kremers's message of "19 Mar 2015 08:12:04 GMT")

Joost Kremers <joost.m.kremers@gmail.com> writes:

> Why not do it at the top level directly? E.g.:
>
> ,----
> | (defvar lh/labels '("label1" "label2" "label3"))
> | 
> | (defmacro lh/gen-predicate (label)
> |   `(defun ,(intern (concat "lh/" label "-p")) ()
> |      (member ,label *lh/system-label-store*)))
> | 
> | (mapc (lambda (label)
> |         (lh/gen-predicate label))
> |       lh/labels)
> `----

That won't work because.  When reading the mapc form, emacs sees that
`lh/gen-predicate' is a macro and tries to expand it with the symbol
label as argument.  The macroexpansion takes place before the actual
execution of the code.

Bye,
Tassilo



  reply	other threads:[~2015-03-19  8:31 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-19  6:53 Concern around use of eval Les Harris
2015-03-19  8:00 ` 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 [this message]
     [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  0:06               ` Johan Bockgård
2015-03-21  7:26                 ` Tassilo Horn
2015-03-21  2:33               ` Stefan Monnier
2015-03-21  7:55                 ` Tassilo Horn

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