Mailman 3 October 2013 - Python-Dev

summing integer and class
by Igor Vasilyev Oct. 3, 2013

Oct. 3, 2013

Hi. Example test.py: class A(): def __add__(self, var): print("I'm in A class") return 5 a = A() a+1 1+a Execution: python test.py I'm in A class Traceback (most recent call last): File "../../test.py", line 7, in <module> 1+a TypeError: unsupported operand type(s) for +: 'int' and 'instance' So adding integer to class works fine, but adding class to integer fails. I could not understand why it happens. In objects/abstact.c we have the following function: static PyObject * binary_op1(PyObject *v, PyObject *w, const int op_slot) { PyObject *x; binaryfunc slotv = NULL; binaryfunc slotw = NULL; if (v->ob_type->tp_as_number != NULL) slotv = NB_BINOP(v->ob_type->tp_as_number, op_slot); if (w->ob_type != v->ob_type && w->ob_type->tp_as_number != NULL) { slotw = NB_BINOP(w->ob_type->tp_as_number, op_slot); if (slotw == slotv) slotw = NULL; } if (slotv) { if (slotw && PyType_IsSubtype(w->ob_type, v->ob_type)) { x = slotw(v, w); if (x != Py_NotImplemented) return x; Py_DECREF(x); /* can't do it */ slotw = NULL; } x = slotv(v, w); if (x != Py_NotImplemented) return x; Py_DECREF(x); /* can't do it */ } if (slotw) { x = slotw(v, w); if (x != Py_NotImplemented) return x; Py_DECREF(x); /* can't do it */ } Py_RETURN_NOTIMPLEMENTED; } When we adding class to integer we have both slotv and slotw. x = slotv(v, w); -> returns Py_NotImplemented. But in this case we should execute x = slotw(v, w); and function should be completed in the same way as when we adding integer to class. Can someone advise please where I mistake. -- thanks, Igor Vasilyev

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Re: [Python-Dev] [Python-checkins] cpython: [issue19151] Fix issue number in Misc/NEWS entry.
by A.M. Kuchling Oct. 3, 2013

Oct. 3, 2013

On Thu, Oct 03, 2013 at 08:48:47PM +0200, eric.snow wrote: > -- Issue #19951: Fix docstring and use of _get_suppported_file_loaders() to > +- Issue #19151: Fix docstring and use of _get_suppported_file_loaders() to ^^^ likely a typo? --amk

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summing integer and class
by Игорь Васильев Oct. 3, 2013

Oct. 3, 2013

Hi. Example test.py: class A(): def __add__(self, var): print("I'm in A class") return 5 a = A() a+1 1+a Execution: python test.py I'm in A class Traceback (most recent call last): File "../../test.py", line 7, in <module> 1+a TypeError: unsupported operand type(s) for +: 'int' and 'instance' So adding integer to class works fine, but adding class to integer fails. I could not understand why it happens. In objects/abstact.c we have the following function: static PyObject * binary_op1(PyObject *v, PyObject *w, const int op_slot) { PyObject *x; binaryfunc slotv = NULL; binaryfunc slotw = NULL; if (v->ob_type->tp_as_number != NULL) slotv = NB_BINOP(v->ob_type->tp_as_number, op_slot); if (w->ob_type != v->ob_type && w->ob_type->tp_as_number != NULL) { slotw = NB_BINOP(w->ob_type->tp_as_number, op_slot); if (slotw == slotv) slotw = NULL; } if (slotv) { if (slotw && PyType_IsSubtype(w->ob_type, v->ob_type)) { x = slotw(v, w); if (x != Py_NotImplemented) return x; Py_DECREF(x); /* can't do it */ slotw = NULL; } x = slotv(v, w); if (x != Py_NotImplemented) return x; Py_DECREF(x); /* can't do it */ } if (slotw) { x = slotw(v, w); if (x != Py_NotImplemented) return x; Py_DECREF(x); /* can't do it */ } Py_RETURN_NOTIMPLEMENTED; } When we adding class to integer we have both slotv and slotw. x = slotv(v, w); -> returns Py_NotImplemented. But in this case we should execute x = slotw(v, w); and function should be completed in the same way as when we adding integer to class. Can someone advise please where I mistake. -- thanks, Igor Vasilyev

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Re: [Python-Dev] cpython: Use cached builtins.
by Antoine Pitrou Oct. 3, 2013

Oct. 3, 2013

On Wed, 2 Oct 2013 18:16:48 +0200 (CEST) serhiy.storchaka <python-checkins(a)python.org> wrote: > http://hg.python.org/cpython/rev/d48ac94e365f > changeset: 85931:d48ac94e365f > user: Serhiy Storchaka <storchaka(a)gmail.com> > date: Wed Oct 02 19:15:54 2013 +0300 > summary: > Use cached builtins. What's the point? I don't think it's a good idea to uglify the code if there isn't a clear benefit. Regards Antoine.

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PEP-431 non-status
by Lennart Regebro Oct. 2, 2013

Oct. 2, 2013

Hi all! If you wonder about the lack of progress reports on pep-431, this is because of a lack of progress. I simply haven't had any time to work on this. I considered make a kickstarter so I could take time off from working, but to be honest, even with that, I still have no time to realistically get this in before beta 1. Sorry about that! //Lennart

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Re: [Python-Dev] cpython (2.7): Add fake buildbottouch target.
by Antoine Pitrou Oct. 2, 2013

Oct. 2, 2013

On Mon, 30 Sep 2013 16:18:57 +0200 (CEST) martin.v.loewis <python-checkins(a)python.org> wrote: > http://hg.python.org/cpython/rev/c1a294bbb4fa > changeset: 85882:c1a294bbb4fa > branch: 2.7 > parent: 85877:dd55d54b2a15 > user: Martin v. Löwis <martin(a)v.loewis.de> > date: Mon Sep 30 16:18:31 2013 +0200 > summary: > Add fake buildbottouch target. "make touch" does exist in 2.7, so was this new target needed? Regards Antoine.

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Re: [Python-Dev] cpython: Close #10042: functools.total_ordering now handles NotImplemented
by Antoine Pitrou Oct. 1, 2013

Oct. 1, 2013

On Tue, 1 Oct 2013 16:02:26 +0200 (CEST) nick.coghlan <python-checkins(a)python.org> wrote: > http://hg.python.org/cpython/rev/ad9f207645ab > changeset: 85913:ad9f207645ab > user: Nick Coghlan <ncoghlan(a)gmail.com> > date: Wed Oct 02 00:02:03 2013 +1000 > summary: > Close #10042: functools.total_ordering now handles NotImplemented > > (Patch by Katie Miller) Ahah, one less annoyance in the stdlib :-) Thank you! Antoine.

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Released: Python 2.6.9 release candidate 1
by Barry Warsaw Oct. 1, 2013

Oct. 1, 2013

Hello Pythoneers and Pythonistas, I'm happy to announce the availability of Python 2.6.9 release candidate 1. Python 2.6.9rc1 is a security-fix source-only release for Python 2.6. This means that general bug maintenance has ended, and only critical security issues are being fixed. It also means that no installers for Windows or Mac OS X will be provided. The last binary release of Python 2.6 was 2.6.6. Python 2.6.9 final is currently scheduled for Monday, October 28, 2013. Five years after the original release of Python 2.6, the 2.6.9 final release will be the last release of the Python 2.6 series. After this, all official maintenance of any kind for Python 2.6 will cease and the series will be retired. For ongoing maintenance, please see Python 2.7. Since 2.6.9 will be the last Python 2.6 release ever, I ask that you please download Python 2.6.9rc1, build it on your favorite platforms, and test it with your favorite code. You can report bugs to the Python bug tracker: http://bugs.python.org The source can be download from: http://www.python.org/download/releases/2.6.9/ You can also see what's changed since Python 2.6.8: http://www.python.org/download/releases/2.6.9/NEWS.txt Many thanks go out to the entire Python community for their contributions and help in making Python 2.6.9 available, especially Jyrki Pulliainen for his patch contributions. Enjoy, -Barry (on behalf of the Python development community)

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Python for new users
by Nick Efford Oct. 1, 2013

Oct. 1, 2013

In the 'PEP453 ready for pronouncement' thread, Donald said >> Because reality is that new users are still likely to be using Python 2.7. >> Python 3 is just now starting to be really usable, however there's a huge >> corpus of existing tutorials, course work, books etc for Python 2.7. As >> Python 3 becomes more usable that existing corpus of material will be >> ported over to Python 3 but in the interim there is still a pretty large >> hurdle for new users to get over. And Guido replied > Based on my day-to-day experience this is still very true. (And yes, I'm > slowly turning the tide. But it will take a long time and I am committed to > giving users the choice.) Widely-used and linked web resources tend to persist for a very long time, so we shouldn't use the prevalence of Python 2 resources as a reason for excessive caution. The key question is how much good material is available based on Python 3 - and this has improved significantly over the past couple of years. The classic "How to Think Like a Computer Scientist" has an excellent Python 3 version available at http://interactivepython.org, for example. Things are changing with print media, too. Pragmatic Programmers are about to publish the 2nd edition of "Practical Programming", based on Python 3. Most of the major academic publishers have released Python 3 books in the last 12 months. The tide is definitely turning, perhaps has already turned. Encouraging the continued use of 2.7 for existing programmers is entirely justifiable, but for *newcomers* to programming I think it is now much harder to justify. A stronger case could have been made a couple of years ago, when many important packages were not yet available for Python 3, but things have changed. Even big frameworks like Django are now usable with Python 3. If we aren't yet past the point where package availability shouldn't be regarded as an adoption barrier by beginners, we are surely very close. I've been teaching Python as a first language to university students for many years now, initially with Python 2 and for the last few years with Python 3. In my experience, they encounter fewer problems with Python 3 (just as Guido intended, no doubt :) The one stumbling block in the past has been package availability for project work, but I don't expect that to a problem this year. All of the web and GUI development work that they'll be doing with me, for example, will be done entirely in Python 3. Nick

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