Path: csiph.com!usenet.pasdenom.info!news.redatomik.org!newsfeed.xs4all.nl!newsfeed2a.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 0.000 X-Spam-Evidence: '*H*': 1.00; '*S*': 0.00; 'parameters': 0.04; 'argument': 0.05; 'guido': 0.05; '(using': 0.07; '*args,': 0.09; '__init__': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'python': 0.11; 'def': 0.12; 'jan': 0.12; 'sections': 0.14; '__new__': 0.16; 'args,': 0.16; 'buggy': 0.16; 'builtins': 0.16; 'expecting': 0.16; 'highlight': 0.16; 'object()': 0.16; 'received:80.91.229.3': 0.16; 'received:plane.gmane.org': 0.16; 'reedy': 0.16; 'subject:object': 0.16; 'subject:skip:m 10': 0.16; 'typeerror:': 0.16; 'wrote:': 0.18; 'obviously': 0.18; 'header:User-Agent:1': 0.23; 'error': 0.23; 'new,': 0.24; 'passes': 0.24; 'tracker': 0.26; 'header:X -Complaints-To:1': 0.27; 'header:In-Reply-To:1': 0.27; 'url:bugs': 0.29; 'am,': 0.29; 'andrew': 0.30; 'change,': 0.30; 'code': 0.31; '"",': 0.31; '>>>>': 0.31; 'object.': 0.31; 'yes.': 0.31; 'file': 0.32; 'class': 0.32; 'worked': 0.33; 'url:python': 0.33; '(most': 0.33; 'skip:_ 10': 0.34; 'core': 0.34; 'something': 0.35; 'but': 0.35; 'doing': 0.36; 'method': 0.36; 'url:org': 0.36; 'depends': 0.38; 'to:addr:python-list': 0.38; 'issue': 0.38; 'recent': 0.39; 'to:addr:python.org': 0.39; 'changed': 0.39; 'received:org': 0.40; 'break': 0.61; 'new': 0.61; 'first': 0.61; 'happen': 0.63; 'decided': 0.64; 'behavior': 0.77; "'object'": 0.84; '3.4': 0.84; 'received:fios.verizon.net': 0.84 X-Injected-Via-Gmane: http://gmane.org/ To: python-list@python.org From: Terry Reedy Subject: Re: Basic misunderstanding on object creation Date: Wed, 13 May 2015 12:36:09 -0400 References: <25ba3a96-21ee-4a83-b7c1-8ac60508d30c@googlegroups.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Gmane-NNTP-Posting-Host: pool-98-114-97-173.phlapa.fios.verizon.net User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 In-Reply-To: <25ba3a96-21ee-4a83-b7c1-8ac60508d30c@googlegroups.com> X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.20+ 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: 43 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1431534990 news.xs4all.nl 2930 [2001:888:2000:d::a6]:34448 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:90567 On 5/13/2015 9:25 AM, andrew cooke wrote: > The following code worked on Python 3.2, but no longer works in 3.4. Bugfixes break code that depends on buggy behavior. See https://bugs.python.org/issue1683368 Your code also fails in 2.7.9 if you inherit Foo from object. The exact error messages changed for 3.4 in https://bugs.python.org/issue7963 > Did something change, Obviously yes. > or have I always been doing something dumb? You were depending on behavior of object that Guido decided was buggy. I found the tracker issue by looking for 'object' in the Core and Builtins sections of the changelog one can access from What's New, first paragraph (using Highlight All in Firefox). >>>> class Foo: > ... def __new__(cls, *args, **kargs): > ... print('new', args, kargs) > ... super().__new__(cls, *args, **kargs) > ... >>>> class Bar(Foo): > ... def __init__(self, a): > ... print('init', a) > ... >>>> Bar(1) > new (1,) {} > Traceback (most recent call last): > File "", line 1, in > File "", line 4, in __new__ > TypeError: object() takes no parameters > > What I was expecting to happen (and what happens in 3.2) is that the object.__new__ method passes the argument to the __init__ of the subclass. -- Terry Jan Reedy