From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Thorsten Jolitz Newsgroups: gmane.emacs.help Subject: Re: Hash tables - how to look up values? Date: Wed, 04 Jul 2012 16:31:02 +0200 Message-ID: <87txxnbntl.fsf@googlemail.com> References: <873957d4di.fsf@googlemail.com> <877guj62jf.fsf@gnu.org> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: dough.gmane.org 1341412123 335 80.91.229.3 (4 Jul 2012 14:28:43 GMT) X-Complaints-To: usenet@dough.gmane.org NNTP-Posting-Date: Wed, 4 Jul 2012 14:28:43 +0000 (UTC) To: help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Wed Jul 04 16:28:43 2012 Return-path: Envelope-to: geh-help-gnu-emacs@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 1SmQZN-0004b4-7Q for geh-help-gnu-emacs@m.gmane.org; Wed, 04 Jul 2012 16:28:41 +0200 Original-Received: from localhost ([::1]:36608 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SmQZM-00042t-4Q for geh-help-gnu-emacs@m.gmane.org; Wed, 04 Jul 2012 10:28:40 -0400 Original-Received: from eggs.gnu.org ([208.118.235.92]:35413) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SmQZE-00042W-5c for help-gnu-emacs@gnu.org; Wed, 04 Jul 2012 10:28:36 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SmQZ8-0008M2-0z for help-gnu-emacs@gnu.org; Wed, 04 Jul 2012 10:28:31 -0400 Original-Received: from plane.gmane.org ([80.91.229.3]:34186) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SmQZ7-0008Ld-QJ for help-gnu-emacs@gnu.org; Wed, 04 Jul 2012 10:28:25 -0400 Original-Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1SmQZ5-000456-K4 for help-gnu-emacs@gnu.org; Wed, 04 Jul 2012 16:28:23 +0200 Original-Received: from e178191004.adsl.alicedsl.de ([85.178.191.4]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 04 Jul 2012 16:28:23 +0200 Original-Received: from tjolitz by e178191004.adsl.alicedsl.de with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Wed, 04 Jul 2012 16:28:23 +0200 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 25 Original-X-Complaints-To: usenet@dough.gmane.org X-Gmane-NNTP-Posting-Host: e178191004.adsl.alicedsl.de User-Agent: Gnus/5.130002 (Ma Gnus v0.2) Emacs/24.0.93 (gnu/linux) Cancel-Lock: sha1:pdgQUdHFI2KkfpoGLQTHgzvn98w= X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 80.91.229.3 X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.14 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-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.help:85656 Archived-At: Bastien writes: Hi Bastien, >> I could not find such a function - does it exist already? > > I don't think so. But here is a start: > > (let (key-found) > (maphash (lambda (key val) > (when (equal val "my_value") > (setq key-found key))) > hashtest) > key-found) > > Of course, the shortcoming is that it stops at the first key it finds, > and discards multiple keys if several have the same value. Thanks, now I even have the 'agony of choice' (is that how they call it in English?), but I might very well need both solutions - return the first or all values found. -- cheers, Thorsten