Path: csiph.com!fu-berlin.de!uni-berlin.de!not-for-mail From: Peter Otten <__peter__@web.de> Newsgroups: comp.lang.python Subject: Re: UserList - which methods needs to be overriden? Date: Thu, 09 Jun 2016 11:40:03 +0200 Organization: None Lines: 29 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8Bit X-Trace: news.uni-berlin.de 91LFt6T5CWEcTvTMJ0unGw/usHJUlvE7cVCZFH7YVw6A== Return-Path: X-Original-To: python-list@python.org Delivered-To: python-list@mail.python.org X-Spam-Status: OK 0.001 X-Spam-Evidence: '*H*': 1.00; '*S*': 0.00; 'finally:': 0.05; 'override': 0.07; 'type,': 0.07; 'inherited': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'subclass': 0.09; 'subject:which': 0.09; 'collections.': 0.16; 'empty.': 0.16; 'pop()': 0.16; 'received:80.91.229.3': 0.16; 'received:dip0.t-ipconnect.de': 0.16; 'received:io': 0.16; 'received:plane.gmane.org': 0.16; 'received:psf.io': 0.16; 'received:t-ipconnect.de': 0.16; 'sources,': 0.16; 'userdict': 0.16; 'wrote:': 0.16; 'proposed': 0.20; 'seems': 0.23; 'header :User-Agent:1': 0.26; '(which': 0.26; 'header:X-Complaints-To:1': 0.26; 'figure': 0.27; 'checking': 0.27; 'sequence': 0.27; 'container': 0.29; 'modified,': 0.29; "i'm": 0.30; 'classes': 0.30; 'too.': 0.30; 'becomes': 0.30; 'checked': 0.31; 'skip:s 30': 0.31; 'source': 0.33; "i'll": 0.33; 'list': 0.34; 'but': 0.36; 'there': 0.36; 'to:addr:python-list': 0.36; 'subject:?': 0.36; 'subject:: ': 0.37; 'method': 0.37; 'received:org': 0.37; 'thought': 0.37; 'anything': 0.38; 'sure': 0.39; 'easily': 0.39; 'to:addr:python.org': 0.40; 'received:de': 0.40; 'some': 0.40; 'ever': 0.60; 'skip:u 10': 0.61; 'nagy': 0.84; 'this...': 0.84; 'subject:needs': 0.93 X-Injected-Via-Gmane: http://gmane.org/ X-Gmane-NNTP-Posting-Host: p57bd9048.dip0.t-ipconnect.de User-Agent: KNode/4.13.3 X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.22 Precedence: list List-Id: General discussion list for the Python programming language List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Mailman-Original-Message-ID: X-Mailman-Original-References: Xref: csiph.com comp.lang.python:109716 Nagy László Zsolt wrote: > I would like to create a collections.UserList subclass that can notify > others when the list is mutated. I'm not sure which methods I need to > override. I have checked the sources, and it seems difficult to figure > out which methods needs to be overriden. For example, > MutableSequence.extend is just a for loop that calls append(). Also, the > clear() method just calls pop() until the sequence becomes empty. But > UserList overrides extend, so if I ever want to know when the list is > modified, I need to override extend() too. There are lots of base > classes (UserList, MutableSequence, Sequence ) etc and some mutating > methods might be inherited from those. I'll also have to do this for > UserDict (which is a MutableMapping, which is a Mapping). > > Is there a way to easily find out which methods of are mutating the > collection? Other than going over the source and checking all (normal > and inherited) methods? How about set(dir(collections.UserList)) - set(dir(collections.Sequence)) > And finally: set is a built in container type, but we don't have a > UserSet in collections. Was it ever proposed to be added to collections? I thought it was the other way round and UserList/UserDict were only kept for backwards-compatibility, but don't find anything in the docs to support this...