Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!goblin2!goblin.stu.neva.ru!newsfeed.xs4all.nl!newsfeed3a.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 0.029 X-Spam-Evidence: '*H*': 0.94; '*S*': 0.00; 'referring': 0.07; 'result,': 0.07; 'def': 0.12; '>>': 0.16; 'clear.': 0.16; 'ought': 0.16; 'sequence.': 0.16; 'should.': 0.16; 'spam"': 0.16; 'subject: \n ': 0.16; 'subject:More': 0.16; 'travis': 0.16; 'wrote:': 0.18; 'value.': 0.19; 'feb': 0.22; '>>>': 0.22; 'input': 0.22; '>>>': 0.24; 'mathematical': 0.24; '>': 0.26; 'header:In-Reply-To:1': 0.27; 'function': 0.29; 'message- id:@mail.gmail.com': 0.30; "d'aprano": 0.31; 'steven': 0.31; 'subject:other': 0.31; 'another': 0.32; 'received:google.com': 0.35; 'there': 0.35; 'functions.': 0.36; 'ordered': 0.36; 'should': 0.36; 'example,': 0.37; 'represent': 0.38; 'to:addr :python-list': 0.38; 'pm,': 0.38; 'skip:& 20': 0.39; '12,': 0.39; 'to:addr:python.org': 0.39; 'called': 0.40; 'even': 0.60; 'then,': 0.60; 'course': 0.61; 'such': 0.63; 'map': 0.64; 'provide': 0.64; 'between': 0.67; '2014,': 0.84; 'subject:!)': 0.84; 'subject:via': 0.84 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=eNVbLsinAuR/OpFTdRGXHCtJPUbWMyy3l/bbe9P3KLo=; b=Tbe6YeA/RCp9QdVR17sWlEj3IkFTYwKZ2VdKySRUhXcMfyePtths0Yh+3bxm+qwJDr yrszqFG0n1f/G4MFnu/wmOjlcKtTdlpogXJzjhW/d9q4X2m3SiIzVl5mXDuHIYyNIztt YXPnDDKITmI1wPGt3glS85UhHBTFcIL3ScyEfobJUFRoqHo51A22CSFYJlNkxdIMdM4W GSvj4ww3RpSPh9+N4myRgdPYCAagPLYipITWr1zM69JDD7Al4fXRjsSPGBcBx2KJpuVg F/ALCKNjweLRSMqxzfqJncEav2AQbDwx7mHYDXwW69zU6OgU2IsZMzOYyWya/Ly7S+/c yWrg== MIME-Version: 1.0 X-Received: by 10.68.129.201 with SMTP id ny9mr4644000pbb.70.1392328805708; Thu, 13 Feb 2014 14:00:05 -0800 (PST) In-Reply-To: <52fc45e6$0$11128$c3e8da3@news.astraweb.com> References: <85c2698c-d681-4511-b111-bb1e549ece93@googlegroups.com> <52f9c392$0$11128$c3e8da3@news.astraweb.com> <52fc45e6$0$11128$c3e8da3@news.astraweb.com> Date: Thu, 13 Feb 2014 15:00:05 -0700 Subject: Re: PyWart: More surpises via "implict conversion to boolean" (and other steaming piles!) From: Ian Kelly To: Python Content-Type: multipart/alternative; boundary=047d7b10cae5dff6e304f250cf80 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: 79 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1392328815 news.xs4all.nl 2850 [2001:888:2000:d::a6]:39222 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:66260 --047d7b10cae5dff6e304f250cf80 Content-Type: text/plain; charset=ISO-8859-1 On Feb 12, 2014 9:16 PM, "Steven D'Aprano" wrote: > > On Tue, 11 Feb 2014 07:36:34 -0800, Travis Griggs wrote: > > > On Feb 10, 2014, at 10:30 PM, Steven D'Aprano > > wrote: > > > > > >>> 1. Parenthesis should not be required for parameter- less > >>> functions. > >> > >> Of course they should. Firstly, parameter-less functions are a code- > >> smell, and ought to be discouraged. Secondly, even if you have a good > >> reason for using one -- for example, random.random -- then the > >> difference between referring to the object and calling the object > >> should be clear. > > > > Interesting. Can you clarify or provide some links to the > > "parameter-less functions are a code-smell" bit? > > > Functions map a value to another value. They can be one-to-one, or many- > to-one. (Mathematically, they cannot be one-to-many or many-to-many, > that's called a relation.) What about zero-to-one? > > If the function always returns the same result, e.g.: > > def spam(): > return "spam spam spam" That's still one-to-one. There is no such thing as a zero-to-one mapping. Mathematical functions map a single value to a single value. To represent multi-argument functions then, the single input takes on the value of an ordered sequence. The input value of a 0-argument function then is the empty sequence. --047d7b10cae5dff6e304f250cf80 Content-Type: text/html; charset=ISO-8859-1


On Feb 12, 2014 9:16 PM, "Steven D'Aprano" <steve@pearwood.info> wrote:
>
> On Tue, 11 Feb 2014 07:36:34 -0800, Travis Griggs wrote:
>
> > On Feb 10, 2014, at 10:30 PM, Steven D'Aprano <steve@pearwood.info>
> > wrote:
> >
> >
> >>>    1. Parenthesis should not be required for parameter- less
> >>>    functions.
> >>
> >> Of course they should. Firstly, parameter-less functions are a code-
> >> smell, and ought to be discouraged. Secondly, even if you have a good
> >> reason for using one -- for example, random.random -- then the
> >> difference between referring to the object and calling the object
> >> should be clear.
> >
> > Interesting. Can you clarify or provide some links to the
> > "parameter-less functions are a code-smell” bit?
>
>
> Functions map a value to another value. They can be one-to-one, or many-
> to-one. (Mathematically, they cannot be one-to-many or many-to-many,
> that's called a relation.) What about zero-to-one?
>
> If the function always returns the same result, e.g.:
>
> def spam():
>     return "spam spam spam"

That's still one-to-one. There is no such thing as a zero-to-one mapping.

Mathematical functions map a single value to a single value. To represent multi-argument functions then, the single input takes on the value of an ordered sequence. The input value of a 0-argument function then is the empty sequence.

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