From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: "Garreau\, Alexandre" Newsgroups: gmane.emacs.help Subject: Re: `when' vs. `and' / `unless' vs `or' Date: Wed, 17 Oct 2018 02:02:28 +0200 Message-ID: <871s8pl9t7.fsf@portable.galex-713.eu> References: <87o9btob5k.fsf@portable.galex-713.eu> <99393ed6-6947-4246-ad8e-b4984c776a53@default> <87zhvdldoh.fsf@portable.galex-713.eu> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Trace: blaine.gmane.org 1539734472 28665 195.159.176.226 (17 Oct 2018 00:01:12 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Wed, 17 Oct 2018 00:01:12 +0000 (UTC) User-Agent: Gnus (5.13), GNU Emacs 25.1.1 (i686-pc-linux-gnu) Cc: help-gnu-emacs@gnu.org To: Drew Adams Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Wed Oct 17 02:01:08 2018 Return-path: Envelope-to: geh-help-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1gCZGu-0007NB-2P for geh-help-gnu-emacs@m.gmane.org; Wed, 17 Oct 2018 02:01:08 +0200 Original-Received: from localhost ([::1]:60639 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gCZIz-0008Uo-TN for geh-help-gnu-emacs@m.gmane.org; Tue, 16 Oct 2018 20:03:17 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:44599) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gCZIJ-0008Tw-54 for help-gnu-emacs@gnu.org; Tue, 16 Oct 2018 20:02:36 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gCZII-0003wl-9S for help-gnu-emacs@gnu.org; Tue, 16 Oct 2018 20:02:35 -0400 Original-Received: from portable.galex-713.eu ([2a00:5884:8305::1]:41448) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gCZII-0003pK-05 for help-gnu-emacs@gnu.org; Tue, 16 Oct 2018 20:02:34 -0400 Original-Received: from localhost ([::1] helo=portable.galex-713.eu) by portable.galex-713.eu with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1gCZID-0001v6-6C; Wed, 17 Oct 2018 02:02:29 +0200 X-GPG-FINGERPRINT: E109 9988 4197 D7CB B0BC 5C23 8DEB 24BA 867D 3F7F X-Accept-Language: fr, en, it, eo In-Reply-To: (Drew Adams's message of "Tue, 16 Oct 2018 16:21:06 -0700 (PDT)") X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2a00:5884:8305::1 X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: Users list for the GNU Emacs text editor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Original-Sender: "help-gnu-emacs" Xref: news.gmane.org gmane.emacs.help:118288 Archived-At: Le 16/10/2018 =C3=A0 16h21, Drew Adams a =C3=A9crit=C2=A0: >> Okay, so what about when you care about the result, but absolutely not >> about the return value of the condition? >>=20 >> (unless cond body) vs (or cond body) -> `or' might imply you might want >> to return cond. > > I don't understand the question. I use (or ...) when I want to return > the value of a disjunction, where that value, if non-nil, might be > any non-nil Lisp value. If (or cond body) returns cond then it's > because cond is non-nil? What's the question? I was just saying in the first case it will return nil while in the second it will return cond (the first arg), so if you don=E2=80=99t want to return cond (because it=E2=80=99s not what you want) you=E2=80=99ll end up = with (and (not cond) body). > (And there is no "cond" as in condition versus "body" as in body. `or' > just returns the first non-nil arg, or nil if none is non-nil.) It was just to use the same arg names, it doesn=E2=80=99t change anything a= s you say. > What's a "big-condition"? A condition of more than a single sexp, such as (and cond cond) instead of just cond (which may be (=3D x 1), so that it would have instead (and (=3D x 1) (=3D x 2)) for instance). > I use `if' when the code cares about the return value, just like > `or' and `and'. If the code doesn't care about the return value, > and if there is only one condition, then I use `when' or `unless'. > Dunno what you mean. Isn't what less easy to understand than > what? (if (or cond cond) then else) than, canonically (and (not (and (or cond cond) then)) else) (not sure about a simplified version), which is the way to write it without an `if', as you said you didn=E2=80=99t use it if t= he condition was more than a single sexp.