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Path: ...!weretis.net!feeder8.news.weretis.net!fu-berlin.de!uni-berlin.de!not-for-mail From: dn <PythonList@DancesWithMice.info> Newsgroups: comp.lang.python Subject: Re: Two python issues Date: Wed, 6 Nov 2024 10:41:59 +1300 Organization: DWM Lines: 60 Message-ID: <mailman.85.1730843499.4695.python-list@python.org> References: <700403c2-e052-4670-b2ec-eaf9b4babada@pandora.be> <CANy1k1iML9=cKxhQfASBZDwqc_4N_E66MgXhddPf6zna3G-ckw@mail.gmail.com> <8faeaf6f-0110-41bd-9e21-1fc4d57b42ae@DancesWithMice.info> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Trace: news.uni-berlin.de HAMVfsCkeEKvjmCjITPO8whEf+zIgZ084+0cKTqot+sg== Cancel-Lock: sha1:FIt8Z+qCH0XI4xcCj9VV9dHm80Y= sha256:NbIjLsr8cfxlHkR/Tn6VfPRfjl07NCPyMDXWn3bF/kk= Return-Path: <PythonList@DancesWithMice.info> X-Original-To: python-list@python.org Delivered-To: python-list@mail.python.org Authentication-Results: mail.python.org; dkim=pass reason="2048-bit key; unprotected key" header.d=danceswithmice.info header.i=@danceswithmice.info header.b=iZAkOB7q; dkim-adsp=pass; dkim-atps=neutral X-Spam-Status: OK 0.014 X-Spam-Evidence: '*H*': 0.97; '*S*': 0.00; "python's": 0.05; 'cpu': 0.07; '=dn': 0.09; 'example:': 0.09; 'from:addr:danceswithmice.info': 0.09; 'from:addr:pythonlist': 0.09; 'questions:': 0.09; 'situations': 0.09; 'subject:python': 0.10; '"not': 0.16; '"where': 0.16; '(will': 0.16; 'apis': 0.16; 'duplication': 0.16; 'found"': 0.16; 'languages.': 0.16; 'message- id:@DancesWithMice.info': 0.16; 'option.': 0.16; 'received:51.254': 0.16; 'received:51.254.211': 0.16; 'received:51.254.211.219': 0.16; 'received:cloud': 0.16; 'received:rangi.cloud': 0.16; 'says:': 0.16; 'wrote:': 0.16; 'problem': 0.16; 'subject:issues': 0.19; 'to:addr:python-list': 0.20; 'idea': 0.24; 'seems': 0.26; 'bit': 0.27; '>>>': 0.28; 'think': 0.29; 'error': 0.29; 'header:User-Agent:1': 0.30; 'answers': 0.32; 'objects': 0.32; 'python-list': 0.32; 'returning': 0.32; 'said,': 0.32; 'header:Organization:1': 0.32; 'but': 0.32; "i'm": 0.33; 'there': 0.33; 'header:In-Reply-To:1': 0.34; 'requires': 0.34; 'item': 0.35; 'currently': 0.37; 'using': 0.37; 'received:192.168': 0.37; 'url-ip:151.101.0.223/32': 0.38; 'url-ip:151.101.128.223/32': 0.38; 'url-ip:151.101.192.223/32': 0.38; 'url-ip:151.101.64.223/32': 0.38; 'both': 0.38; 'use': 0.39; 'two': 0.39; 'still': 0.40; '(see': 0.40; 'should': 0.40; 'reference': 0.60; 'method': 0.61; 'above': 0.62; 'skip:b 20': 0.63; 'your': 0.64; 'received:51': 0.64; 'time.': 0.66; 'bad': 0.67; 'apply.': 0.69; 'refers': 0.69; 'sequence': 0.69; 'within': 0.69; 'content': 0.72; 'little': 0.73; 'major': 0.78; 'position': 0.81; 'study': 0.82; 'indicates': 0.84; 'similarly': 0.84; 'thus,': 0.84; 'performs': 0.93 DKIM-Filter: OpenDKIM Filter v2.11.0 vps.rangi.cloud DA1268264 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=danceswithmice.info; s=staff; t=1730842924; bh=cB9S2zxBjN6e6rDv9ibZOdhB59p39Q9cKEw2JHACk0c=; h=Date:From:Subject:To:References:In-Reply-To:From; b=iZAkOB7qKQowLHb2g7GgZ06onXPhmb671BHoMRmerK3T1llcnQjq0hVtFjrnmxBGM bDkECSr/9vuYoFd1qGckxrW7ykQneIMUN4JG/WILKrvjkDOF1zNuQuQg5/veSlRzfT SqRCMSu9ItV5SGEoCRGyq44QrV4NmX/MeOXgBjSd3+aEfkCMmM4j3vQBy9bXyixwWO 3KimHxeKNSJCwhqDXyPsPx/GVOvTqQPhEscf20NZObZuYsNuPcWB5OAxJoszWISB4I 9HS0F+oBBJscKn0vOqSzR5x7DpvpyNC1Ll1mT42cMGkCItPHRu/YRzZ7WM6En0RQ4E 3B0SU1Zn+Cc/w== User-Agent: Mozilla Thunderbird Content-Language: en-US In-Reply-To: <CANy1k1iML9=cKxhQfASBZDwqc_4N_E66MgXhddPf6zna3G-ckw@mail.gmail.com> X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.39 Precedence: list List-Id: General discussion list for the Python programming language <python-list.python.org> List-Unsubscribe: <https://mail.python.org/mailman/options/python-list>, <mailto:python-list-request@python.org?subject=unsubscribe> List-Archive: <https://mail.python.org/pipermail/python-list/> List-Post: <mailto:python-list@python.org> List-Help: <mailto:python-list-request@python.org?subject=help> List-Subscribe: <https://mail.python.org/mailman/listinfo/python-list>, <mailto:python-list-request@python.org?subject=subscribe> X-Mailman-Original-Message-ID: <8faeaf6f-0110-41bd-9e21-1fc4d57b42ae@DancesWithMice.info> X-Mailman-Original-References: <700403c2-e052-4670-b2ec-eaf9b4babada@pandora.be> <CANy1k1iML9=cKxhQfASBZDwqc_4N_E66MgXhddPf6zna3G-ckw@mail.gmail.com> Bytes: 6530 On 6/11/24 10:08, Jason Friedman via Python-list wrote: >> >> (a) An error-prone "feature" is returning -1 if a substring is not found >> by "find", since -1 currently refers to the last item. An example: >> >> >>> s = 'qwertyuiop' >> >>> s[s.find('r')] >> 'r' >> >>> s[s.find('p')] >> 'p' >> >>> s[s.find('a')] >> 'p' >> >>> >> >> If "find" is unsuccessful, an error message is the only clean option. >> Moreover, using index -1 for the last item is a bad choice: it should be >> len(s) - 1 (no laziness!). >> > > I'm not sure if this answers your objection but the note in the > documentation (https://docs.python.org/3/library/stdtypes.html#str.find) > says: > > The find() method should be used only if you need to know the position of > sub. > > I think the use case above is a little bit different. Not really, there are two questions: 1. is x in sequence (or in this case "not in") 2. where is x within sequence (find()) There are situations where one might be used, similarly where the other will be used, and still more where both apply. That said, and with @Cameron's observation, the idea that a function's return-value (appears to) performs two functionalities is regarded as a 'code-smell' in today's world - either it indicates "found" or it indicates "where found" (see also various APIs which return both a boolean: success/fail, and a value: None/valid-info). The problem with the third scenario being that purity suggests we should use both (1) and (2) which seems like duplication - and is certainly going to take more CPU time. (will such be noticeable in your use-case?) Backward-compatibility... ('nuff said!) With reference to the OP content about slicing: - Python's memory-addressing is different from many other languages. Thus, requires study before comparison/criticism - there are major differences in what can be accomplished with mutable and immutable objects -- Regards, =dn