From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: =?UTF-8?Q?Andreas_R=c3=b6hler?= Newsgroups: gmane.emacs.help Subject: Re: (copy-marker nil) Date: Mon, 7 May 2018 16:23:17 +0200 Message-ID: <181880cf-6962-72a2-2c65-25d4b884d3e9@easy-emacs.de> References: <364c8f2d-06ab-4f81-852f-eb3bac7a0615@easy-emacs.de> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit X-Trace: blaine.gmane.org 1525702841 10137 195.159.176.226 (7 May 2018 14:20:41 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Mon, 7 May 2018 14:20:41 +0000 (UTC) User-Agent: Mozilla/5.0 (X11; Linux i686; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 To: John Mastro , Help Gnu Emacs mailing list Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Mon May 07 16:20:37 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 1fFh0G-0002XS-FM for geh-help-gnu-emacs@m.gmane.org; Mon, 07 May 2018 16:20:36 +0200 Original-Received: from localhost ([::1]:46541 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fFh2N-0006wt-IB for geh-help-gnu-emacs@m.gmane.org; Mon, 07 May 2018 10:22:47 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:52325) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fFh1i-0006uB-Sc for help-gnu-emacs@gnu.org; Mon, 07 May 2018 10:22:10 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fFh1f-0005w2-Ff for help-gnu-emacs@gnu.org; Mon, 07 May 2018 10:22:06 -0400 Original-Received: from mout.kundenserver.de ([212.227.126.131]:40231) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1fFh1f-0005us-6l for help-gnu-emacs@gnu.org; Mon, 07 May 2018 10:22:03 -0400 Original-Received: from [192.168.178.35] ([188.103.18.182]) by mrelayeu.kundenserver.de (mreue003 [212.227.15.167]) with ESMTPSA (Nemesis) id 0Lj7Ag-1ekUwJ1TPK-00dDQt; Mon, 07 May 2018 16:22:01 +0200 In-Reply-To: Content-Language: en-US X-Provags-ID: V03:K1:bQ8sTUYmUHEIvrkyzjYCl40VY8fVhLcDwb3rxGr2y6lTbJmD1Pg dtAsOvktDBGvPD3DAJQ73m7cxO77vMfsP8SYKrXsktAc+H72DVs8xfGiYS52NB6EIfSaoYt NCK0307XWTjnIpTxkMbvdE+eNFdVsmKVwzfQ0WJuQg7d4y5xUeFYv1mhs6uACR7Cr7a1cc7 YhWkpTKPW/jZrBubqOfmQ== X-UI-Out-Filterresults: notjunk:1;V01:K0:NalJxXJnryQ=:/VHuWv6Pj0UTSkFA2jCnpS /L0TwR9/q0x4bfFMkdZCzmSdLxu7UI2xdR+AOH5x0UlGw9cBfwHa8laXgW1UTmfoIZJvbFUkz h7lC6wQSXqr1Q+j1qfoAOMyVwumqCS2AqcokGZVaeXNJ5iVF7Xk3wdT+BKHtdl/SQxL+sIP2M mzuBXn/DJww4GDoqvt8dHcCS0IdQAHZFPyswdBG6bwgj5qV5a10N8lCHaet0r/apirVnvgION tP7znTAVeCT+FZE9spp8fE2/3Wh6TZZZL1Z6Ia0c6b7HDT/PCs7QCFqOBJ7zfJe8eLqNFiCPW t2h01nKhO8vBptdQEGEn3S5a8JaLH9XRyiqFbhJmEP9jWgaU+kGhXpLBs0uY5SW70IFANdbpy L98CDa6dbh8hWxDRNj+2+mhFmQBv6vWFiWFDo/VpuKcg0wo7jISK4voNgU6bLPPhKWdqQWziQ dneLXenhDuNTCqWBFl6pGDV7gGngN33foMO25ys8WVav+2vjGHdocxSG1Hbl8agaxOvMGSkCe 4qvHbi/SKOVNktWs76Pi+/c5pTGFK2FRj0gTajXybsKAbJ1Rflfj0VbFFdVmPSn2SEh7pPxbB B30jYoLuMHOjQynQB6Dq4/BkMMW223GP+ZwRHLqWVN5qXYwPgx8bsjzAA/PaQ6/G5Os5kRZ4x NwIsN+jGmufhAPE+db6JRBqOt/4z+bGU1/CzvQv2ufD9t+angaW9S7Ux+5Msr1b8YwJ7b3PwA N/WSwuNUZWsiGS5R X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 212.227.126.131 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:116676 Archived-At: On 07.05.2018 15:39, John Mastro wrote: > Andreas Röhler wrote: >> being surprised WRT behavior of copy-marker: >> >> (setq a (copy-marker nil)) -> # >> (markerp a) -> t >> a -> # >> >> Is taking nil by copy-marker reasonable? >> >> Wanted to check for a valid buffer position, which doesn't seem >> possible that way. While without copy-marker, the variable a would be >> set to nil, now the result evaluates to #, which >> is a kind of t. > > There are other ways to get a marker to no buffer, such as > > (let ((a (point-marker))) > (set-marker a nil)) > > So if you don't control the creation of the marker, it's probably a > scenario you need to take care for either way. > > Explicitly testing the marker's buffer should work: > > (let ((a (copy-marker nil))) > (and (markerp a) > (buffer-live-p (marker-buffer a)))) > Thanks. A way to deal with ;)