Mailman 3 September 2007 - Python-Dev

Errors in the csv module reader/writer methods - new w/ change to rst?
by skip＠pobox.com 05 Sep '07

05 Sep '07

I was just looking for some csv DictWriter examples for a colleague at work and was myself confused by the apparent transformation which took place in the Reader Objects and Writer Objects sections. Each of the methods is now prefixed by "csv.csvreader." or "csv.csvwriter." Neither expression was previously defined in that section. Those undefined expressions are not in the old versions of the documentation, e.g.: http://www.python.org/doc/2.4.4/lib/node634.html http://www.python.org/doc/2.4.4/lib/node635.html http://www.python.org/doc/2.5/lib/node265.html http://www.python.org/doc/2.5/lib/node266.html I don't think they add anything useful to the documentation. Were they added just for the csv module (and possibly a few others) or was this a change to the entire libref documentation? That is, was this some sort of policy change? Can they be removed? Skip

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python sphinx install?
by Neal Becker 05 Sep '07

05 Sep '07

I'm interested in trying out new style (python 2.6) documentation. I see we're using docutils + sphinx? I did: svn co http://svn.python.org/projects/doctools/trunk/ How can I install this to try it with python-2.5?

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Porting information
by Ty Newton 04 Sep '07

04 Sep '07

Hi, I'm looking into porting CPython to native C# (not like IronPython) so that it can be used in game software on the XBox360: integrated with the indie development tool XNA Game Studio Express. I am looking for some guidance on how to approach this in the most effective way. I've started by looking at the parser portion of the code. However I am not certain this is the best place to start. Since there are so many ports I assume there is a well trodden path to completing this kind of task. Any suggestions would be greatly appreciated. I would prefer to break the task into portions that can be verified (tested for correctness) independently or as a stack (one on top of the next). That way I can catch errors early and have more confidence in what I am creating. When I looked through the test suites they all seem to be written in Python. Is there a test suite for the core of CPython i.e. before the C code can interpret Python code? Thanks, Ty

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Math.sqrt(-1) -- nan or ValueError?
by Hasan Diwan 04 Sep '07

04 Sep '07

I'm trying to fix a failing unit test in revision 57974. The test in question claims that math.sqrt(-1) should raise ValueError; the code itself gives "nan" as a result for that expression. I can modify the test and therefore have it pass, but I'm not sure if an exception would be more appropriate. I'd be happy for some direction here. Many thanks! -- Cheers, Hasan Diwan <hasan.diwan(a)gmail.com>

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Re: [Python-Dev] frozenset C API?
by Raymond Hettinger 04 Sep '07

04 Sep '07

[Bill Janssen] > > How about this one, though: > > PyDict_NEW(int) => PySetObject * > PyDict_ADD(s, value) > > ADD would just stick value in the next > empty slot (and steal its reference). Dicts, sets and frozenset are implemented as hash tables, not as arrays, so the above suggestion doesn't make any sense to me. The location of the "next empty slot" depends on a the key associated with the value being added (btw, where is the "key" handled in your proposed API?). Consequently, the PyDict_New(int) step would have no way to know where to create the n empty slots (since their location is determined by the hash value of the keys). That is a reason that the tuple/list API differs from the set/frozenet/dict API. Raymond

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Compiling cpython2.5.1 in VS2005?
by Ty Newton 04 Sep '07

04 Sep '07

Hi, I was building Python 2.5.1 in Visual Studio 2005 and noticed some problems with the instructions. Can someone confirm this and update the readme file in the PCbuild8 directory? I don't yet have access to the repository. This is what the readme.txt file says to do: <snip> All you need to do is open the workspace "pcbuild.sln" in VisualStudio 2005, select the platform, select the Debug or Release setting (using "Solution Configuration" from the "Standard" toolbar"), and build the solution. The proper order to build subprojects: 1) pythoncore (this builds the main Python DLL and library files, python25.{dll, lib} in Release mode) NOTE: in previous releases, this subproject was named after the release number, e.g. python20. 2) python (this builds the main Python executable, python.exe in Release mode) </snip> This is my experience. DEBUG configuration: When I select 'pythoncore' (right click) from the solution explorer, select 'project only', select 'build only pythoncore' I get this error report: Warning 1 warning C4005: 'Yield' : macro redefinition E:\Program Files\Microsoft Visual Studio 8\VC\PlatformSDK\include\winbase.h 57 Warning 2 warning C4005: 'Yield' : macro redefinition E:\Program Files\Microsoft Visual Studio 8\VC\PlatformSDK\include\winbase.h 57 Error 3 fatal error C1083: Cannot open source file: '.\getbuildinfo2.c': No such file or directory c1 It looks like the project dependencies are not kicking in. I assume this is caused by building the project instead of the solution. So I did them manually. First make_versioninfo project: I select 'make_versioninfo' (right click) from the solution explorer, select 'project only', select 'build only make_versioninfo'. This succeeds. Second make_buildinfo project: I select 'make_buildinfo' (right click) from the solution explorer, select 'project only', select 'build only make_buildinfo'. This succeeds. Finally I try to make pythoncore again: I select 'pythoncore' (right click) from the solution explorer, select 'project only', select 'build only pythoncore'. This succeeds. Now I build python and it also succeeds. One last thing I noticed is if there are spaces in the path of the source files the compilation also fails. Regards, Ty

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Re: [Python-Dev] frozenset C API?
by Raymond Hettinger 04 Sep '07

04 Sep '07

You can create a frozenset from any iterable using PyFrozenSet_New(). If you don't have an iterable and want to build-up the frozenset one element at a time, the approach is to create a regular set (or some other mutable container), add to it, then convert it to a frozenset when you're done: s = PySet_New(NULL); PySet_Add(s, obj1); PySet_Add(s, obj2); PySet_Add(s, obj3); f = PyFrozenSet_New(s); Py_DECREF(s); That approach is similar to what you do with tuples in pure python. You either build them from an iterable "t = tuple(iterable)" or your build-up a mutable object one element at a time and convert it all at once: s = [] s.append(obj1) s.append(obj2) t = tuple(s) The API you propose doesn't work because sets and frozensets are not indexed like tuples and lists. Accordingly, sets and frozensets have a C API that is more like dictionaries. Since dictionaries are not indexable, they also cannot have an API like the one you propose: PyDict_NEW(int) => PySetObject * PyDict_SET_ITEM(s, index, key, value) If you find all this really annoying and need to fashion a small frozenset with a few known objects, consider using the abstract API: f = PyObject_CallFunction(&PyFrozenSet_Type, "(OOO)", obj1, obj2, obj3); That will roll the whole process up into one line. Hope this was helpful, Raymond --------------------------------------------------------------- Bill Janssen <janssen(a)parc.com>Add To Address Book|This is Spam Subject:[Python-Dev] frozenset C API? To:python-dev@python.org I'm looking at building a "frozenset" instance as a return value from a C function, and the C API seems ridiculously clumsy. Maybe I'm misunderstanding it. Apparently, I need to create a list object, then pass that to PyFrozenSet_New(), then decref the list object. Is that correct? What I'd like is something more like PyFrozenSet_NEW(int) => PySetObject * PyFrozenSet_SET_ITEM(s, i, v) Any idea why these aren't part of the API?

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frozenset C API?
by Bill Janssen 04 Sep '07

04 Sep '07

I'm looking at building a "frozenset" instance as a return value from a C function, and the C API seems ridiculously clumsy. Maybe I'm misunderstanding it. Apparently, I need to create a list object, then pass that to PyFrozenSet_New(), then decref the list object. Is that correct? What I'd like is something more like PyFrozenSet_NEW(int) => PySetObject * PyFrozenSet_SET_ITEM(s, i, v) Any idea why these aren't part of the API? Bill

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Roundup issue mails "Do not thread!"
by O.R.Senthil Kumaran 03 Sep '07

03 Sep '07

Hi all, Has anyone observed missing "email-threads" issue with Roundup bug tracker email? Any work around for that? I use mutt and find that roundup bug issue000xx mails are not being threaded. Its not do with settings, I believe. The issue000xxx emails might not being have In-Reply-To or References: header. <MuttFAQ> Why are some msgs threaded and others not? You have some msgs which don't have correct In-Reply-To: References: headers (or not set at all) and you've turned on $strict_threads What do "->", "-?-" and "*>" mean in thread trees? When you turn off $strict_threads msgs with similar subjects get grouped together. In ... </MuttFAQ> -- O.R.Senthil Kumaran http://uthcode.sarovar.org

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Avoiding cascading test failures
by Alexandre Vassalotti 02 Sep '07

02 Sep '07

When I was fixing tests failing in the py3k branch, I found the number duplicate failures annoying. Often, a single bug, in an important method or function, caused a large number of testcase to fail. So, I thought of a simple mechanism for avoiding such cascading failures. My solution is to add a notion of dependency to testcases. A typical usage would look like this: @depends('test_getvalue') def test_writelines(self): ... memio.writelines([buf] * 100) self.assertEqual(memio.getvalue(), buf * 100) ... Here, running the test is pointless if test_getvalue fails. So by making test_writelines depends on the success of test_getvalue, we can ensure that the report won't be polluted with unnecessary failures. Also, I believe this feature will lead to more orthogonal tests, since it encourages the user to write smaller test with less dependencies. I wrote an example implementation (included below) as a proof of concept. If the idea get enough support, I will implement it and add it to the unittest module. -- Alexandre class CycleError(Exception): pass class TestCase: def __init__(self): self.graph = {} tests = [x for x in dir(self) if x.startswith('test')] for testname in tests: test = getattr(self, testname) if hasattr(test, 'deps'): self.graph[testname] = test.deps else: self.graph[testname] = set() def run(self): graph = self.graph toskip = set() msgs = [] while graph: # find tests without any pending dependencies source = [test for test, deps in graph.items() if not deps] if not source: raise CycleError for testname in source: if testname in toskip: msgs.append("%s... skipped" % testname) resolvedeps(graph, testname) del graph[testname] continue test = getattr(self, testname) try: test() except AssertionError: toskip.update(getrevdeps(graph, testname)) msgs.append("%s... failed" % testname) except: toskip.update(getrevdeps(graph, testname)) msgs.append("%s... error" % testname) else: msgs.append("%s... ok" % testname) finally: resolvedeps(graph, testname) del graph[testname] for msg in sorted(msgs): print(msg) def getrevdeps(graph, testname): """Return the reverse depencencies of a test""" rdeps = set() for x in graph: if testname in graph[x]: rdeps.add(x) if rdeps: # propagate depencencies recursively for x in rdeps.copy(): rdeps.update(getrevdeps(graph, x)) return rdeps def resolvedeps(graph, testname): for test in graph: if testname in graph[test]: graph[test].remove(testname) def depends(*args): def decorator(test): if hasattr(test, 'deps'): test.deps.update(args) else: test.deps = set(args) return test return decorator class MyTest(TestCase): @depends('test_foo') def test_nah(self): pass @depends('test_bar', 'test_baz') def test_foo(self): pass @depends('test_tin') def test_bar(self): self.fail() def test_baz(self): self.error() def test_tin(self): pass def error(self): raise ValueError def fail(self): raise AssertionError if __name__ == '__main__': t = MyTest() t.run()

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