From: Marcin Borkowski <mbork@mbork.pl>
To: Stefan Monnier <monnier@iro.umontreal.ca>
Cc: help-gnu-emacs@gnu.org
Subject: Re: [External] : Re: Why is defun not executed during load-file?
Date: Mon, 31 May 2021 22:09:04 +0200 [thread overview]
Message-ID: <87pmx6acnz.fsf@mbork.pl> (raw)
In-Reply-To: <jwva6oaofeq.fsf-monnier+emacs@gnu.org>
On 2021-05-31, at 21:47, Stefan Monnier via Users list for the GNU Emacs text editor <help-gnu-emacs@gnu.org> wrote:
>> Hm ... interesting. Yeah, maybe we should start do that more?
>
> Not really: it's better to avoid macros when you can.
> But it's better to use macros than to use `eval`.
>
>> What kind of things or problems could or should you solve
>> with macros?
>
> Whenever you find yourself forced to use `eval` ?
Or when you lack some syntactical construct you could find useful, like
anaphoric-if. Or if what you need is closer to a "special form" than to
a function. A typical case is when you need a construct which will be
able to evaluate something or not, depending on the circumstances. Or
when you need a construct which will evaluate some form(s) /after/ doing
something (remember that when a function gets its arguments, they are
all evaluated before even the first form of a function is evaluated!).
Here (shameless plug!) is an example of something you couldn't achieve
with functions alone (unless you wanted to wrap some code in `(lambda ()
...)', which would be rather ugly):
http://mbork.pl/2016-04-24_The_conditional-save-excursion_macro
Hth,
--
Marcin Borkowski
http://mbork.pl
next prev parent reply other threads:[~2021-05-31 20:09 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-30 22:48 Why is defun not executed during load-file? Drew Adams
2021-05-30 22:57 ` Emanuel Berg via Users list for the GNU Emacs text editor
2021-05-31 2:05 ` [External] : " Drew Adams
2021-05-31 2:56 ` Emanuel Berg via Users list for the GNU Emacs text editor
2021-05-31 5:05 ` Drew Adams
2021-05-31 19:20 ` Emanuel Berg via Users list for the GNU Emacs text editor
2021-05-31 19:47 ` Stefan Monnier via Users list for the GNU Emacs text editor
2021-05-31 20:09 ` Marcin Borkowski [this message]
2021-06-07 2:19 ` Emanuel Berg via Users list for the GNU Emacs text editor
2021-06-07 6:27 ` Jean Louis
2021-06-07 14:18 ` FW: " Drew Adams
2021-06-07 14:41 ` Emanuel Berg via Users list for the GNU Emacs text editor
2021-05-31 21:40 ` Example use of macro to minimize and generalize the code Jean Louis
2021-05-31 23:37 ` Michael Heerdegen
2021-05-31 23:59 ` Jean Louis
2021-06-01 0:34 ` Michael Heerdegen
2021-06-01 0:39 ` Jean Louis
2021-06-01 0:59 ` Michael Heerdegen
2021-06-01 1:25 ` Jean Louis
2021-06-01 14:02 ` Michael Heerdegen
2021-06-01 16:33 ` Jean Louis
2021-06-01 16:54 ` Yuri Khan
2021-06-01 17:24 ` Jean Louis
2021-06-01 17:57 ` Yuri Khan
2021-06-01 18:12 ` Jean Louis
2021-05-31 21:45 ` Example use of macro to minimize and generalize the code (2) Jean Louis
2021-05-31 21:48 ` [External] : Re: Why is defun not executed during load-file? Michael Heerdegen
2021-05-31 23:41 ` Drew Adams
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