From: Emanuel Berg <embe8573@student.uu.se>
To: help-gnu-emacs@gnu.org
Subject: Re: if vs. when vs. and: style question
Date: Tue, 24 Mar 2015 00:19:11 +0100 [thread overview]
Message-ID: <878uen1evk.fsf@debian.uxu> (raw)
In-Reply-To: mailman.2645.1427151196.31049.help-gnu-emacs@gnu.org
Marcin Borkowski <mbork@wmi.amu.edu.pl> writes:
> assuming (e1) and (e2) are some expressions, all
> three forms:
>
> (if (e1) (e2))
>
> (when (e1) (e2))
>
> (and (e1) (e2))
>
> are semantically equivalent. Which one is better
> style (and when)? I would guess that =when= is
> better iff (e2) is a =progn= (since we can drop the
> =progn= altogether, and this seems to be the point
> of =when=), and =and= might be considered better
> (well, maybe) by some people when both (e1) and (e2)
> are very short (though I personally would avoid
> that, since =if= seems easier for a human to
> understand at a first glance). Am I right?
I don't think `and' should be used to evaluate and
return =stuff= (I mean evaluate as in side-effects),
rather, use it as the familiar gate of binary logic,
thought here it isn't binary but can be of whatever
arity. But no rule without exceptions, of course...
To me `if' + `progn' is better than `when' because
I am more familiar with those constructs and also, if
I ever have to change something, which happens all the
time, I will not have to bother thinking "is this
still a `progn'? if it isn't, should I remove the
`when'? if I don't, will anyone wonder why I used
a `when' instead of `if'? Less thinking, more coding
I'd say with plain `if' and then whatever is needed
from there to get it done.
But I can't say I'd hit the ceiling if anyone used
`when', with or without the need for a `progn' in the
equivalent `if' clause. Using `and' for no reason I'd
consider worse because that could be really confusing.
--
underground experts united
next parent reply other threads:[~2015-03-23 23:19 UTC|newest]
Thread overview: 109+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <mailman.2645.1427151196.31049.help-gnu-emacs@gnu.org>
2015-03-23 23:19 ` Emanuel Berg [this message]
2015-03-23 22:53 if vs. when vs. and: style question Marcin Borkowski
2015-03-24 0:15 ` Pascal J. Bourguignon
2015-03-24 0:34 ` Drew Adams
2015-03-24 0:22 ` Drew Adams
[not found] ` <mailman.2648.1427156603.31049.help-gnu-emacs@gnu.org>
2015-03-24 2:28 ` Emanuel Berg
2015-03-24 6:12 ` Rusi
2015-03-25 0:21 ` Emanuel Berg
2015-03-25 0:20 ` Pascal J. Bourguignon
2015-03-25 2:44 ` Emanuel Berg
2015-03-25 2:51 ` Rusi
2015-03-25 7:12 ` Pascal J. Bourguignon
2015-03-25 14:02 ` Rusi
2015-03-25 14:40 ` Stefan Monnier
2015-03-25 15:22 ` Pascal J. Bourguignon
2015-03-25 15:37 ` Rusi
2015-03-29 1:17 ` Emanuel Berg
2015-03-25 15:45 ` Rusi
2015-03-29 1:03 ` Emanuel Berg
2015-03-29 2:41 ` Rusi
2015-03-29 3:11 ` Rusi
2015-03-29 14:05 ` Óscar Fuentes
2015-03-29 16:00 ` Drew Adams
2015-03-30 1:55 ` Óscar Fuentes
[not found] ` <mailman.2998.1427680540.31049.help-gnu-emacs@gnu.org>
2015-03-30 2:25 ` Rusi
2015-03-29 18:27 ` Pascal J. Bourguignon
2015-03-30 0:09 ` Stefan Monnier
2015-03-30 1:33 ` Óscar Fuentes
2015-03-30 1:50 ` Stefan Monnier
2015-03-30 9:44 ` tomas
2015-03-30 11:46 ` Óscar Fuentes
[not found] ` <mailman.3016.1427716011.31049.help-gnu-emacs@gnu.org>
2015-03-30 13:03 ` Pascal J. Bourguignon
2015-03-30 14:18 ` Stefan Monnier
2015-03-30 15:21 ` Marcin Borkowski
2015-03-30 15:31 ` Óscar Fuentes
[not found] ` <mailman.3031.1427729518.31049.help-gnu-emacs@gnu.org>
2015-03-30 17:15 ` Pascal J. Bourguignon
[not found] ` <mailman.3010.1427708687.31049.help-gnu-emacs@gnu.org>
2015-03-30 12:59 ` Pascal J. Bourguignon
[not found] ` <mailman.2972.1427637975.31049.help-gnu-emacs@gnu.org>
2015-03-30 1:55 ` Rusi
[not found] ` <mailman.2749.1427294481.31049.help-gnu-emacs@gnu.org>
2015-03-25 15:33 ` Rusi
2015-03-25 15:36 ` Pascal J. Bourguignon
2015-03-25 16:06 ` Drew Adams
[not found] ` <mailman.2751.1427299594.31049.help-gnu-emacs@gnu.org>
2015-03-25 16:19 ` Rusi
2015-03-25 16:23 ` Rusi
2015-03-29 1:24 ` Emanuel Berg
2015-03-25 17:02 ` Dan Espen
2015-03-25 18:23 ` Drew Adams
[not found] ` <mailman.2758.1427307846.31049.help-gnu-emacs@gnu.org>
2015-03-25 18:52 ` Dan Espen
2015-03-26 9:47 ` Gian Uberto Lauri
2015-03-29 23:06 ` Emanuel Berg
[not found] ` <mailman.2799.1427363259.31049.help-gnu-emacs@gnu.org>
2015-03-26 10:24 ` Pascal J. Bourguignon
2015-03-26 10:28 ` Pascal J. Bourguignon
2015-03-26 10:43 ` Gian Uberto Lauri
2015-03-26 13:02 ` Pascal J. Bourguignon
2015-04-01 22:03 ` Emanuel Berg
2015-04-01 22:24 ` Emanuel Berg
2015-03-25 19:17 ` Pascal J. Bourguignon
2015-03-25 20:31 ` Drew Adams
2015-03-25 22:21 ` Richard Wordingham
2015-03-25 23:21 ` Drew Adams
2015-03-25 23:52 ` Richard Wordingham
[not found] ` <mailman.2782.1427325697.31049.help-gnu-emacs@gnu.org>
2015-03-26 3:02 ` Rusi
2015-03-26 10:01 ` Gian Uberto Lauri
[not found] ` <mailman.2800.1427364117.31049.help-gnu-emacs@gnu.org>
2015-03-26 13:00 ` Rusi
2015-03-26 13:28 ` Gian Uberto Lauri
[not found] ` <mailman.2809.1427376497.31049.help-gnu-emacs@gnu.org>
2015-03-26 15:51 ` Pascal J. Bourguignon
2015-03-26 16:21 ` Gian Uberto Lauri
[not found] ` <mailman.2779.1427322080.31049.help-gnu-emacs@gnu.org>
2015-04-01 2:31 ` Emanuel Berg
2015-04-01 3:03 ` Rusi
2015-04-01 14:29 ` Pascal J. Bourguignon
2015-04-01 14:57 ` Rusi
[not found] ` <mailman.2771.1427315503.31049.help-gnu-emacs@gnu.org>
2015-03-26 4:23 ` Rusi
2015-03-25 19:20 ` Pascal J. Bourguignon
2015-03-26 11:37 ` Alan Schmitt
2015-03-30 1:20 ` Emanuel Berg
2015-03-30 2:43 ` Pascal J. Bourguignon
2015-03-30 3:12 ` Rusi
2015-03-25 17:49 ` Pascal J. Bourguignon
2015-03-25 18:09 ` Eli Zaretskii
[not found] ` <mailman.2756.1427307016.31049.help-gnu-emacs@gnu.org>
2015-03-25 21:27 ` Rusi
2015-03-25 21:32 ` Rusi
2015-03-31 16:49 ` Emanuel Berg
2015-03-31 17:22 ` Rusi
2015-04-01 18:08 ` Emanuel Berg
2015-04-01 20:01 ` Pascal J. Bourguignon
2015-03-27 3:54 ` Emanuel Berg
2015-03-27 7:59 ` Gian Uberto Lauri
2015-03-27 8:06 ` tomas
2015-03-27 8:11 ` Gian Uberto Lauri
2015-03-27 9:20 ` tomas
2015-03-27 9:31 ` Gian Uberto Lauri
[not found] ` <mailman.2860.1427443603.31049.help-gnu-emacs@gnu.org>
2015-03-27 12:41 ` Pascal J. Bourguignon
2015-03-27 13:05 ` tomas
[not found] ` <mailman.2875.1427461540.31049.help-gnu-emacs@gnu.org>
2015-03-27 13:35 ` Rusi
2015-03-27 12:34 ` Pascal J. Bourguignon
2015-03-27 0:49 ` Emanuel Berg
2015-03-27 7:53 ` Gian Uberto Lauri
[not found] ` <mailman.2856.1427442800.31049.help-gnu-emacs@gnu.org>
2015-03-27 8:56 ` Joost Kremers
2015-03-27 12:19 ` Pascal J. Bourguignon
2015-03-27 14:20 ` Rusi
2015-03-25 2:35 ` Rusi
2015-03-27 0:31 ` Emanuel Berg
2015-03-27 21:27 ` Emanuel Berg
2015-03-27 22:54 ` Pascal J. Bourguignon
2015-03-28 1:16 ` Rusi
2015-03-28 12:47 ` Pascal J. Bourguignon
2015-03-24 15:18 ` Pascal J. Bourguignon
2015-03-25 0:44 ` Emanuel Berg
2015-03-24 7:21 ` Thien-Thi Nguyen
[not found] ` <mailman.2659.1427181547.31049.help-gnu-emacs@gnu.org>
2015-03-25 0:34 ` Emanuel Berg
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