Mailman 3 August 2007 - Python-Dev

make iter() return an empty iterator?
by Facundo Batista 03 Aug '07

03 Aug '07

2007/8/3, Andrew Bennetts <andrew-pythondev(a)puzzling.org>: > I don't really think there's much reason to make "iter()" work. As you say, What bad thing could happen if we make iter() work? If nothing, we should ask ourselves: which is the more intuitive behaviour to expect of iter()? To raise an exception or to return an empty iterator? I'm +0 for the latter. -- . Facundo Blog: http://www.taniquetil.com.ar/plog/ PyAr: http://www.python.org/ar/

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NotImplemented comparisons
by Facundo Batista 03 Aug '07

03 Aug '07

People: Pablo Hoffman opened this bug: "[1764761] Decimal comparison with None fails in Windows". It's not a Decimal problem, see the differente behaviour of this basic test in Linux and Windows: Python 2.5.1 (r251:54863, May 2 2007, 16:56:35) [GCC 4.1.2 (Ubuntu 4.1.2-0ubuntu4)] on linux2 >>> class C(object): ... def __cmp__(self, other): ... return NotImplemented ... >>> c = C() >>> print c < None False >>> print NotImplemented < None False Python 2.5.1 (r251:54863, Apr 18 2007, 08:51:08) [MSC v.1310 32 bit (Intel)] on win32 >>> class C(object): def __cmp__(self, other): return NotImplemented >>> c = C() >>> print c < None True >>> print NotImplemented < None False Here's where I stop: don't know where to keep looking... Does somebody know why is a difference here? Furthermore, we can check that is a problem regarding __cmp__: >>> class C(object): def __cmp__(self, other): return NotImplemented def m(self): return NotImplemented >>> c = C() >>> print c < None True >>> print c.m() < None False This is not the first time I find an issue through Decimal regarding NotImplemented, there was this thread: http://mail.python.org/pipermail/python-dev/2005-December/059046.html , but I don't know if that's a separate issue or not. Thanks for your help! -- . Facundo Blog: http://www.taniquetil.com.ar/plog/ PyAr: http://www.python.org/ar/

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make iter() return an empty iterator?
by Georg Brandl 03 Aug '07

03 Aug '07

Sure, you could use ``iter(())`` or ``iter([])``, but for consistency's sake wouldn't it make sense for ``iter()`` to return an empty iterator, as ``str()`` returns an empty string etc.? Georg -- Thus spake the Lord: Thou shalt indent with four spaces. No more, no less. Four shall be the number of spaces thou shalt indent, and the number of thy indenting shall be four. Eight shalt thou not indent, nor either indent thou two, excepting that thou then proceed to four. Tabs are right out.

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T_PYSSIZET in Include/structmember.h can be hidden
by Neal Norwitz 03 Aug '07

03 Aug '07

Martin, Do you know why T_PYSSIZET is inside a #ifdef HAVE_LONG_LONG? That seems like a mistake. Here's the code: #ifdef HAVE_LONG_LONG #define T_LONGLONG 17 #define T_ULONGLONG 18 #define T_PYSSIZET 19 /* Py_ssize_t */ #endif /* HAVE_LONG_LONG */ ISTM, that T_PYSSIZET should be after the #endif. Was this a mistake or intentional? n

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Re: [Python-Dev] NotImplemented comparisons
by Facundo Batista 02 Aug '07

02 Aug '07

2007/8/2, Paul Moore <p.f.moore(a)gmail.com>: > A wild guess: c < None falls back to checking c.__cmp__(None) < 0. > This translates to NotImplemented < 0, and as the ordering of built in > types is implementation dependent, maybe that explains the difference > between Windows and Linux? "NotImplemented < 0" returns False, which is ok, but different from "c < None" 2007/8/2, Guido van Rossum <guido(a)python.org>: > > But how do you explain the difference in behaviour between Linux and Windows? > > Perhaps the comparison compares the objects' address. No, because NotImplemented and None are always the same: if this is the problem Linux and Windows could be different but they would be consistent with themselves (and Windows is not coherent with itself). Bottom line: I can easily fix Decimal to handle this special case, the point is that maybe we have a lower level bug here... Regards, -- . Facundo Blog: http://www.taniquetil.com.ar/plog/ PyAr: http://www.python.org/ar/

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Re: [Python-Dev] NotImplemented comparisons
by Facundo Batista 02 Aug '07

02 Aug '07

2007/8/2, Guido van Rossum <guido(a)python.org>: > NonImplemented isn't treated as special when returned by __cmp__(); > __cmp__ is not considered a binary operator like __add__. (__lt__ and > friends *do* get treated as such -- but instead of __rlt__ we use > __gt__, etc.) I understand that is tricky how NotImplemented and comparisons interact. But how do you explain the difference in behaviour between Linux and Windows? Thanks! -- . Facundo Blog: http://www.taniquetil.com.ar/plog/ PyAr: http://www.python.org/ar/

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Python Package Index hostname change
by "Martin v. Löwis" 01 Aug '07

01 Aug '07

The Python Packaging Index (the software formerly known as Cheeseshop) is now available at http://pypi.python.org/pypi The old addresses (www.python.org/pypi, and cheeseshop.python.org/pypi) will continue to work, either as aliases or using HTTP redirections. The software was renamed to its old name (PyPI - Python Package Index), as the Cheeseshop name was ever confusing people unfamiliar with British television comedy sketch (and puzzling even to people familiar with the sketch, as you *can* get packages from the package index). If you would like to discuss PyPI and its future, please join catalog-sig(a)python.org. Regards, Martin

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Python-Dev August 2007