Mailman 3 October 2002 - Python-Dev

the not operator (and the __not__ special method)
by Marcelo Matus Oct. 4, 2002

Oct. 4, 2002

Hello: The following test code: class Hello: def __not__(self): return "calling Hello.__not__" def __neg__(self): return "calling Hello.__neg__" a = Hello() print -a print not a shows that python doesn't call the __not__ special method in a 'not' operator statement. The Modules/operator.c file, line 234, says: spam2(neg,__neg__, "neg(a) -- Same as -a.") spam2(pos,__pos__, "pos(a) -- Same as +a.") spam2(abs,__abs__, "abs(a) -- Same as abs(a).") spam2(inv,__inv__, … [View More]

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How to add an encoding alias?
by Guido van Rossum Oct. 4, 2002

Oct. 4, 2002

In the spambayes project we encountered some mail samples that use an encoding name ('ansi-x3-4-1968') that's not in encodings/aliases.py. (At least not until I added it to CVS yesterday.) I'd like the spambayes code base to be compatible with Python 2.2.1, so I like to add this one to the list of aliases. Is there an official API to add an alias, or do I just have to write import encodings.aliases encodings.aliases.aliases['ansi-x3-4-1968'] = 'ascii' ??? (BTW, there's an alias '… [View More]

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Re: [Python-Dev] the not operator (and the __not__ special method)
by Michael Hudson Oct. 4, 2002

Oct. 4, 2002

Oren Tirosh <oren-py-d(a)hishome.net> writes: > On Thu, Oct 03, 2002 at 07:22:15PM -0400, Aahz wrote: > > On Thu, Oct 03, 2002, Brian Quinlan wrote: > > > > > > > shows that python doesn't call the __not__ special method > > > > in a 'not' operator statement. > > > > > > Python calls the special __nonzero__ method so check the truth value of > > > an object. > > > > Mark McEahern provided the full answer: … [View More]

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Offtopic: Microsoft Altair BASIC legend likes Python
by Michael McLay Oct. 4, 2002

Oct. 4, 2002

Some good press for Python: http://www.theregister.co.uk/content/archive/18909.html Twenty six years ago the microprocessor revolution found a software catalyst - a tiny BASIC interpreter that ran in 4K of memory. You've probably heard of two of its three authors - Paul Allen and Bill Gates, who'd incorporated the company 'Micro-Soft' in Albuquerque the same year. The third man, Monte Davidoff, isn't nearly as famous. You'll search in vain for an interview on the web with Monte. So we … [View More]

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PEP 285 (Adding a bool type) extending it further
by Marcelo Matus Oct. 4, 2002

Oct. 4, 2002

Given my silly problems trying to write a class which overwrite logical operations like 'and', 'or' and 'not', which is not possible by now (see the discussion following http://mail.python.org/pipermail/python-dev/2002-October/029122.html ) I would like to propose to extend the PEP 285 to add boolean operations that can be overloaded as the rest of the operations in python. The operations in question refers of course to 'and', 'or' and 'not'. I guess this will involve to add a structure … [View More]

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RE: [Python-Dev] Re: PEP239 (Rational Numbers) Reference Implemen tation and new issues
by Delaney, Timothy Oct. 4, 2002

Oct. 4, 2002

> From: Delaney, Timothy [mailto:tdelaney@avaya.com] > > Do we have double-colons yet? > > a::b Of course we do ... (slices). Tim Delaney

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RE: [Python-Dev] Re: PEP239 (Rational Numbers) Reference Implemen tation and new issues
by Delaney, Timothy Oct. 4, 2002

Oct. 4, 2002

> From: Tim Peters [mailto:tim.one@comcast.net] > > [Delaney, Timothy] > > ... > > Actually, following through my thought processes, ``x:y`` is only > > legal in the context of a sequence slice i.e. inside ``[]``. > > Dicts are worse. {1:2:3} would be hopelessly ambiguous. {(1:2):3} {1:(2:3)} I'm trying to work out a way to get more parentheses in there without surrounding the actual digits ;) But it's another overloading that I missed ... As I said, it's … [View More]

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RE: [Python-Dev] Re: PEP239 (Rational Numbers) Reference Implemen tation and new issues
by Delaney, Timothy Oct. 4, 2002

Oct. 4, 2002

> From: Greg Ewing [mailto:greg@cosc.canterbury.ac.nz] > > > I think the slice notation e.g. x[1:4] kills that idea. > > Maybe if ":" were a sliceobject-creating operator usable > anwyere, not just in [...], and you added arithmetic > methods to sliceobjects so you could use them as > rationals... The sad thing is this is actually tempting to me, given the beauty of using the "ratio" notation ``x:y`` to denote rational literals ... Actually, following through my … [View More]

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Re: PEP239 (Rational Numbers) Reference Implementation and new issues
by Andrew Koenig Oct. 3, 2002

Oct. 3, 2002

By the way, has anyone considered the idea of making operations on rationals faster by never storing any trailing zeroes in the numerator or denominator? Instead, strip them and store the (signed) difference between the number of zeroes you've stripped from the numerator and the number you've stripped from the denominator. In other words, instead of storing (num, denom) and having the number be the (exact) value of num/demon, store (num, denom, exp) and have the number be the (exact) value of … [View More]

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PEP239 (Rational Numbers) Reference Implementation and new issues
by Peter Norvig Oct. 3, 2002

Oct. 3, 2002

I agree with pinard, although I think it is a manageable problem. I went through this transition once, from Symbolics Lisp, in which integer division truncates, to Common Lisp, in which it produces a rational. After only an hour or two of fiddling with my various programs, everything seemed to work; I was very happy. But after a few days, the machine started to slow down mysteriously, especially on wake-up. It took a while to discover the culprit was my screensaver program (which I … [View More]

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