From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Daniel Colascione Newsgroups: gmane.emacs.devel Subject: Re: Generators (iterators) for Gnu Emacs Date: Fri, 05 Dec 2014 17:08:27 -0500 Message-ID: <54822CDB.8080408@dancol.org> References: <877fy77zhp.fsf@web.de> <87lhmm24x9.fsf@gmail.com> <54812545.6030008@dancol.org> <87d27y22lp.fsf@gmail.com> <87lhmmiim7.fsf@gmail.com> <5481D080.7000206@dancol.org> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="FACTlEjwoufThrJQJS26RtkHqUV0ALksL" X-Trace: ger.gmane.org 1417817416 14979 80.91.229.3 (5 Dec 2014 22:10:16 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 5 Dec 2014 22:10:16 +0000 (UTC) Cc: Leo Liu , emacs-devel@gnu.org To: Stefan Monnier Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Fri Dec 05 23:10:10 2014 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1Xx14j-0006rp-8D for ged-emacs-devel@m.gmane.org; Fri, 05 Dec 2014 23:10:09 +0100 Original-Received: from localhost ([::1]:52640 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Xx14i-0005ll-Nq for ged-emacs-devel@m.gmane.org; Fri, 05 Dec 2014 17:10:08 -0500 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:56375) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Xx13G-00040S-1x for emacs-devel@gnu.org; Fri, 05 Dec 2014 17:08:38 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Xx13E-0004pi-BV for emacs-devel@gnu.org; Fri, 05 Dec 2014 17:08:37 -0500 Original-Received: from dancol.org ([2600:3c01::f03c:91ff:fedf:adf3]:40109) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Xx13D-0004oU-Ul for emacs-devel@gnu.org; Fri, 05 Dec 2014 17:08:36 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=dancol.org; s=x; h=Content-Type:In-Reply-To:References:Subject:CC:To:MIME-Version:From:Date:Message-ID; bh=WUT6jC31Q0Z+kv4/6ewFIfurtVJ1MVrP674KIv4P/rY=; b=WpQwFpCUS800yz+ah1aKPBhUO1A9k65WDATgPnclqwRfUENVaBiGdRd+hcs0jk1w4TcTJ8GTialZwtH1sQZHnaS0Wyea6NtjoJAT71auxnZT3NwwIv/EJbspznJu8RT5y9dYTqg/3v3/z99OEqoE9V2jFxLhK9FSOv8nu7V2WQ9fwHvXi3rDKW+HtGonagnLgWqpGsb8q4ybI9Wbqvd1vwcz1oqZsaHI9BZ/AMLP7rYjpvrvkpairRCngLDhBuIgl4nT89WuBEJRadurLrfEw0he3mNYbMfZolZxEgC/oZiU6oYiwtjZcxub4HYGOxXnyX9BT6eopZ4z+AVoX81x/A==; Original-Received: from [2620:10d:c0a3:1003:2ab2:bdff:fe1c:db58] by dancol.org with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.84) (envelope-from ) id 1Xx13B-0007V5-Sq; Fri, 05 Dec 2014 14:08:34 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 In-Reply-To: X-detected-operating-system: by eggs.gnu.org: Error: Malformed IPv6 address (bad octet value). X-Received-From: 2600:3c01::f03c:91ff:fedf:adf3 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:179037 Archived-At: This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --FACTlEjwoufThrJQJS26RtkHqUV0ALksL Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable On 12/05/2014 01:32 PM, Stefan Monnier wrote: >> I'd really rather signal to stop iteration. That way, it's harder to i= gnore >> end-of-iteration and loop forever and it remains possible to iterate o= ver >> *any* value. condition-case is setjmp. I'm not *that* concerned by >> performance. The only other reasonable alternative is for iterators to= >> yield a cons (terminal-p . value), and consing is going to be much wor= se >> than condition-case. >=20 > The alternative I was thinking was to return a unique value, as in: >=20 > (defvar gen-eog (make-symbol "=A1end-of-generator!")) > (defun gen-eog-p (x) (eq x gen-oeg)) >=20 Right. That's the approach I don't like: now there's a value you can't en= umerate. What if you wanted to enumerate, say, the values of all symbols?= =09 --FACTlEjwoufThrJQJS26RtkHqUV0ALksL Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBCAAGBQJUgizbAAoJEN4WImmbpWBlu9IQAJutFZ1BjCgRc3svYJmZdyyY zWm5Go6KvkXd6OyORJnbJOFG4amxLjIYno/LC3sQOo97H81KLlYFDr7ogtbLtGts HcemIzkC3K3bLe4vSkpidYSlnAe7c5ozlET5A0xvQSmwuT69l4Bl14aKfZDoQWnx jMPxG2Uo2xIx4s8LfdEQn1W50C/ESCu1lfqprI59uvMOBeYjf4GE7jBLbKkSTfXa IldwdZSxrjlvNr6NnAj9zAAt3emVG6OOARKdMY96/iHL/ymNFRqShXA7upfgRu+5 RKcf/MM2Me0mBLtvzUMItKDrhYEpHOayWdY7h4K5cIHRqG0G6l9KWWnbIcXvMPc4 7Of9ID2kU3SLkhr3kGRtkvg3yTXZOUjL1fD1awJtTaLp/p+0UO7JAK30Nha8PUFj 0ZjAD+cFvmnjRNRyS3ukUoG2iHcrFAK/ySVhWojcVDBvb3+R+EfsyzdOG3hM9a+f Ek6r2D5AWbZL8EpgRJmPn9fD/VNZrwx/5Zj5sYhhlFRJyHdcDei7VQMl+GL7Wd4n OSx9L3WQH4M3FuYpQ7DdARJJUjddsmJUBU0mqXijy1kPliFtR1v0Ha+pemXAmb3I h1JMRN4Am306D7Dx6Gunwx1lIeGDhHQYXzER1C0KJTDIJBKp5VB4xa7BwDWgjpAx /bwP86R2ccHgtGw068Tp =EkAy -----END PGP SIGNATURE----- --FACTlEjwoufThrJQJS26RtkHqUV0ALksL--