From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Heime Newsgroups: gmane.emacs.help Subject: Re: [External] : Use of an associated list with completing-read Date: Sat, 20 Apr 2024 06:37:08 +0000 Message-ID: References: <1ZznhcKDmGMQcjaA3pyQaBOnYG81YwX4pE1YSoGxi_Vj_UFqz_DzTcdhZ50XnL3lEDivoq5THtGr-ShAq1PMbkmNHxajYrXWeRmti6_BSD4=@protonmail.com> <6IDPPDE6NaK72davfT7rnK8S553m9H8sBdCDy8UqV81_uCoMjrGuIjErQYACxxx5LZjd2Np0R9S2RPCqIFanRLNpVZhEGvXNYfqBrYI0ahw=@protonmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="39726"; mail-complaints-to="usenet@ciao.gmane.io" Cc: Stefan Monnier , help-gnu-emacs@gnu.org To: Heime Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Sat Apr 20 08:37:55 2024 Return-path: Envelope-to: geh-help-gnu-emacs@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1ry4ME-000A4r-T5 for geh-help-gnu-emacs@m.gmane-mx.org; Sat, 20 Apr 2024 08:37:54 +0200 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ry4Lf-0002NK-Cd; Sat, 20 Apr 2024 02:37:19 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ry4Ld-0002Me-VX for help-gnu-emacs@gnu.org; Sat, 20 Apr 2024 02:37:18 -0400 Original-Received: from mail-4319.protonmail.ch ([185.70.43.19]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1ry4Lc-0000Jx-0g for help-gnu-emacs@gnu.org; Sat, 20 Apr 2024 02:37:17 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonmail.com; s=protonmail3; t=1713595033; x=1713854233; bh=/VvZa4EiLTfFxrEi1ECNv6gbwEpHZ3agsg1leixMuoU=; h=Date:To:From:Cc:Subject:Message-ID:In-Reply-To:References: Feedback-ID:From:To:Cc:Date:Subject:Reply-To:Feedback-ID: Message-ID:BIMI-Selector; b=mBpiLmx8gQEj8iAq/4hjKhKu5UyKldAXVncSP6vnVWHXnwtirGdoP6fq23Uk5xmvX nl4CS373kBJ76HUT3wGATapuhuVOGWfvf8NB4fhoq1J3EZWprLTAxQ6z+63VH/Gmz7 DgQsFQlxUMfbFHUZcCvGMv7+PEFVu6zbkkv+c0+8D7RU+0p+2qDTx7w3VWMqxgy2J7 mzsamC74BcNd+FfqwDi3zEKQL9H4C8fnAERvul+Z0EDAzUov6pqjQtWXLJ21sYVS3G Vh78tbu+XpFamCSBYFrt4jqSKLpWuWu5h1Ch8qUmXl2Sm+R9GYYHP7igRj3nZIzCXA t9xx0S8u4rwTQ== In-Reply-To: Feedback-ID: 57735886:user:proton X-Pm-Message-ID: 132fdd48a1e0305ff43054ec9b1de3389d84ee99 Received-SPF: pass client-ip=185.70.43.19; envelope-from=heimeborgia@protonmail.com; helo=mail-4319.protonmail.ch X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001, TO_EQ_FM_DIRECT_MX=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.29 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-mx.org@gnu.org Original-Sender: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.help:146397 Archived-At: On Saturday, April 20th, 2024 at 6:14 PM, Heime wrote: > On Saturday, April 20th, 2024 at 1:52 PM, Stefan Monnier via Users list f= or the GNU Emacs text editor help-gnu-emacs@gnu.org wrote: >=20 > > > > > (setq-local tema-lugar > > > > > (append tema--lugar (list (cons lnum strg)))) > > > >=20 > > > > This is the classic recipe for poor scaling performance since the a= bove > > > > operation takes time proportional to the length of the list, so if = you > > > > execute this N times (in a loop), the loop builds a list of length = N > > > > but takes time N=C2=B2 to do it. When N is small, noone notices, an= d as it gets > > > > large the performance starts to suck. > > >=20 > > > Heime: > > >=20 > > > One programming cliche for this is to > > > (1) start with a list that you create > > > (e.g., a let-binding to nil), so you > > > don't modify any existing list that > > > you might not want to mess with, (2) > > > use `nconc' instead of` append', to > > > append quickly (the list structure > > > is modified - destructive), (3) being > > > sure to set your list variable to the > > > result of each modification. > >=20 > > While this is slightly better because it avoid the O(N=C2=B2) memory > > allocation, it's still O(N=C2=B2) operations. > >=20 > > > An even more common cliche for doing > > > the same thing is to do #1, then (2) > > > cons instead of append, and (3) when > > > finished adding list elements, do an > > > `nreverse' of the list you created. > > > That too is a destructive operation. > >=20 > > That's the usual solution, with the desired linear > > (i.e. optimal) complexity, indeed. - Stefan >=20 >=20 > How would the implementation be like exactly ? Would a solution be like this ? =20 (push (cons kfrz lnum) tema-lugar)