Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!news.mixmin.net!rt.uk.eu.org!newsfeed.xs4all.nl!newsfeed2.news.xs4all.nl!xs4all!post.news.xs4all.nl!not-for-mail Return-Path: X-Original-To: python-list@python.org Delivered-To: python-list@mail.python.org X-Spam-Status: OK 0.003 X-Spam-Evidence: '*H*': 0.99; '*S*': 0.00; 'subject:error': 0.03; 'subject:not': 0.03; 'uses.': 0.09; 'python': 0.11; 'behavior:': 0.16; 'expressions,': 0.16; 'key/datum': 0.16; 'partly': 0.16; 'reedy': 0.16; 'runtime.': 0.16; 'subject:key': 0.16; 'subject:when': 0.16; 'throw': 0.16; 'wrote:': 0.18; 'slightly': 0.19; 'thu,': 0.19; 'error': 0.23; '"you': 0.24; '31,': 0.24; 'case.': 0.24; 'documented': 0.24; 'simpler': 0.24; 'skip:{ 20': 0.24; 'specify': 0.24; 'initial': 0.24; 'define': 0.26; 'equivalent': 0.26; 'updating': 0.26; 'certain': 0.27; 'header:In- Reply-To:1': 0.27; 'wondering': 0.29; 'am,': 0.29; 'generally': 0.29; 'message-id:@mail.gmail.com': 0.30; 'keys': 0.31; 'something': 0.35; 'but': 0.35; 'received:google.com': 0.35; 'returning': 0.36; 'expected': 0.38; 'to:addr:python-list': 0.38; 'list,': 0.38; 'pm,': 0.38; 'sure': 0.39; 'to:addr:python.org': 0.39; 'changed': 0.39; 'course': 0.61; "you're": 0.61; 'times': 0.62; 'design,': 0.64; '8bit%:21': 0.69; 'jul': 0.74; 'dict()': 0.84 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :content-type:content-transfer-encoding; bh=6h35jjU2THHYzTs9OM3gXoo63OYWBVJrrnTjd5bWqPE=; b=AyoWIOhZ/AXlfiE2FvS0YSBabiJg77Ek5tY7vb8HzcenxfgzRE3VToWmH3hV845lCa KMjTRWN2yD9bh3aGJXKeE/IyawLCahB4iJYE1va1z5Erj2Oia4bCTfvsFsYQnZu+i7ex u0oyG/C0v2eA5pzSBqHj+70BY3ItOKYbTXwO8yJup7FQ+jfYBXTqdtc8xAeud7ZVL23l RPBKcRf1pcwFPSOF0lRPO7awGzy2pjZ6HOvzNqW7nUcMUH5LYGb63sWiS/iP4Ps0PbZU nz/DzJ8rHxDvrHjUPyv676HD3dSbI/JLD3OpAmWQrqEMdSSMq3XkPFrvVVOLLwO6NJ1o gpXg== X-Received: by 10.68.65.101 with SMTP id w5mr881763pbs.5.1406841455339; Thu, 31 Jul 2014 14:17:35 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: From: Ian Kelly Date: Thu, 31 Jul 2014 15:16:55 -0600 Subject: Re: Dict when defining not returning multi value key error To: Python Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: General discussion list for the Python programming language List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Newsgroups: comp.lang.python Message-ID: Lines: 28 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1406841464 news.xs4all.nl 2932 [2001:888:2000:d::a6]:50669 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:75444 On Thu, Jul 31, 2014 at 1:17 PM, Terry Reedy wrote: > On 7/31/2014 7:24 AM, Dilu Sasidharan wrote: > >> I am wondering why the dictionary in python not returning multi value >> key error when i define something like >> >> p =3D {'k':"value0",'k':"value1"} > > > This is documented behavior: "you can specify the same key multiple times= in > the key/datum list, and the final dictionary=E2=80=99s value for that key= will be > the last one given." I am not sure whether this is an accident of the > initial design, never changed since, or intended for certain uses. It ma= y > partly be because this choice is slightly simpler or, since keys are > expressions, not constants, that the check can only come at runtime. I don't know either, but I think that it's generally expected that the above would be equivalent to: p =3D dict() p['k'] =3D "value0" p['k'] =3D "value1" which of course will not throw an error since you're just updating the value in that case.