Mailman 3 May 2012 - Python-ideas

Re: [Python-ideas] I have an encrypted python module format: .pye
by Mike Graham May 14, 2012

May 14, 2012

On Fri, May 11, 2012 at 6:27 PM, li wang <charlesw123456(a)gmail.com> wrote: > > I want to use python in my product because I like and familiar with > python for many years, but I won't let the customer to read and modify > my code. So the best way is to encrypt my module .py to .pye. They scheme you describe only provides a false sense of security. That would be very bad. The only ways to protect your code are a) legally, which is the main one, and b) by not giving it to … [View More]

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Move tarfile.filemode() into stat module
by Giampaolo Rodolà May 13, 2012

May 13, 2012

http://hg.python.org/cpython/file/9d9495fabeb9/Lib/tarfile.py#l304 I discovered this undocumented function by accident different years ago and reused it a couple of times since then. I think that leaving it hidden inside tarfile module is unfortunate. What about moving it into stat module and document it? Regards, --- Giampaolo http://code.google.com/p/pyftpdlib/ http://code.google.com/p/psutil/ http://code.google.com/p/pysendfile/

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I have an encrypted python module format: .pye
by li wang May 13, 2012

May 13, 2012

hi all: I want to use python in my product because I like and familiar with python for many years, but I won't let the customer to read and modify my code. So the best way is to encrypt my module .py to .pye. Now python will write compiled byte code .pyc or .pyo when a .py is imported, I have write a patch to add .pye support for encrypted byte code. When a .pye is imported, python will check the environment variable PYTHONENCRYPT, if this environment variable is defined with non-blank value,… [View More]

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Printf function?
by Carl M. Johnson May 13, 2012

May 13, 2012

I was looking at this jokey page on the evolution of programming language syntax -- http://alan.dipert.org/post/153430634/the-march-of-progress -- and it made me think about where Python is now. The Python 2 version of the example from the page is print "%10.2f" % x and the Python 3 is print("{:10.2f}".format(x)) Personally, I prefer the new style {} formatting to the old % formatting, but it is pretty busy when you want to do a print and format in one step. Why not add a printf function … [View More]

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Re: [Python-ideas] bool(datetime.time(0, 0)) vs missing data
by Jim Jewett May 10, 2012

May 10, 2012

On Wed, May 9, 2012 at 2:07 AM, Antoine Pitrou <solipsis(a)pitrou.net> wrote: > On Tue, 8 May 2012 20:53:58 -0400 > Jim Jewett <jimjjewett(a)gmail.com> wrote: >> On Mon, May 7, 2012 at 12:06 PM, Antoine Pitrou <solipsis(a)pitrou.net> wrote: >> > ... Does midnight warrant any special ... >> Why do you think that 0 represents midnight? *Because* it is zero, >> it will often be used as a default for missing data. > Well, if you've … [View More]decided upfront that midnight "is zero", then you may > argue it's special. But as others have shown, there's nothing obvious > about midnight being "zero", especially with timezones factored in. > For example, there are no binary operators where midnight is a "zero" > i.e. a neutral element. The cyclic groups Z/n have a zero element, so *something* has to be effectively zero; start of day is as reasonable as anything else. Or are you just saying that there aren't *any* meaningful binary operators on hour-of-the-day, beyond __eq__ and __ne__? Practicality Beats Purity suggests that at least comparisons should work consistently, so that time-of-day can be consistently ordered, and that requires a least element. (You could make it noon, or mean sunrise, or actual sundown at a certain monument, but you do need one.) > Besides, we have a special value called None exactly for the purpose of > representing missing data. Not really at the moment, since datetime.time doesn't accept it as an argument, and itself uses 0 for missing data. That could *probably* be fixed in an upwards compatible way, but you would still have to special case how missing-data times should compare to current class instances. # Should they ever be equal? # If not, mixing types is a problem. time(hour, min, sec, microsecond) == Time(hour, min, sec, microsecond) ? # Should microseconds be required? # If not, mixing types is a problem. time(hour, min, sec, microsecond=0) == Time(hour, min, sec, microsecond=None) ? # Should even hours be required? # If so, how much precision is logically required? time(hour=0, min=0, sec=0, microsecond=0) == Time(hour=None, min=None, sec=None, microsecond=None) ? # datetime.time already skips the date. # Can hours be skipped too, to indicate "every hour on the hour"? Time(hour=None, min=0, sec=0, microsecond=0) ? # Should missing data never match, match 0, or match anything (the "on the hour" case) time(hour=7, min=15, sec=0, microsecond=0) == Time(hour=None, min=15, sec=0, microsecond=0) ? -jJ [View Less]

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bool(datetime.time(0, 0))
by Ram Rachum May 9, 2012

May 9, 2012

Hello, Currently, `bool(datetime.time(0, 0)) is False`. Can we change that to `True`? There is nothing False-y about midnight. Ram.

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Module __getattr__ [Was: breaking out of module execution]
by Jim Jewett May 8, 2012

May 8, 2012

On Wed, Apr 25, 2012 at 2:35 PM, Matt Joiner <anacrolix(a)gmail.com> wrote: > If this is to be done I'd like to see all special methods supported. One of > particular interest to modules is __getattr__... For What It's Worth, supporting __setattr__ and __getattr__ is one of the few reasons that I have considered subclassing modules. The workarounds of either offering public set_varX and get_varX functions, or moving configuration to a separate singleton, just feel kludgy. Since … [View More]

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Replacing shelve in the next 3.x release.
by Jakob Bowyer May 7, 2012

May 7, 2012

I suggest that we either replace the internals of shelve, or deprecate it, or remove it in favour of other dbm's like http://packages.python.org/sqlite3dbm/dbm.html. Many people feel that shelve is a pointless module that should not be used because it relies too much on pickle an insecure format, in my own searches Google showed only 13 projects using shelve and Github showed only 3000 odd snippets containing shelve.open so its time this module either died quietly or got the internals replaced. … [View More]

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Should range() == range(0)?
by Terry Reedy May 7, 2012

May 7, 2012

It is a general principle that if a built-in class C has a unique (up to equality) null object, then C() returns that null object. >>> for f in (bool, int, float, complex, tuple, list, dict, set, frozenset, str, bytes, bytearray): print(bool(f())) # 12 lines of False Some imported classes such as fractions.Fraction and collections.deque can be added to the list. I add 'up to equality' because in the case of floats, 0.0 and -0.0 are distinct but equal, and float() returns the … [View More]obvious 0.0. >>> 0.0 == -0.0 True >>> m.copysign(1, 0.0) 1.0 >>> m.copysign(1, -0.0) -1.0 >>> m.copysign(1, float()) 1.0 The notable exception to the rule is >>> range() Traceback (most recent call last): File "<pyshell#0>", line 1, in <module> range() TypeError: range expected 1 arguments, got 0 >>> bool(range(0)) False It is true that there are multiple distinct null range objects (because the defining start,stop,step args are kept as attributes) but they are all equal. >>> range(1,1) == range(0) True range(0) == range(0, 0, 1) would be the obvious choice for range(). Another advantage of doing this, beside consistency, is that it would emphasize that range() produces a re-iterable sequence, not just an iterator. Possible objections and responses: 1. This would slightly complicate the already messy code and doc for range(). Pass, for now. 2. There is little need as there is already the alternative. This is just as true or even more true for the other classes. While int() is slightly easier to type than int(), 0 is even easier. 3. There is little or no use case. The justification I have seen for all the other classes behaving as they do is expressions like type(x)(), which gets the null object corresponding to x. This requires a parameterless call rather than a literal (or display) or call with typed arg. A proper objection this sort would have to argue that range() is less useful than all 12+ cases that we have now. 4. memoryview() does not work. Even though memoryview(bytes()) and memoryview(bytearray()) are both False and equal, other empty memoryviews would not all be equal. Besides which, a memoryview is dependent on another object, and there is not reason to create any particular object for it to be dependent on. 5. The dict view methods, such as dict.keys, do not work. These also return views that are dependent on a primary object, and the views also are null if the primary object is. Here there is a unique null primary object, so it would at least be possible to create an empty dict whose only reference is held by a read-only view. On the other hand, '.keys' is a function, not a class. 6. filter() does not work. While filter is a class, its instances, again, are dependent on another object, not just at creation but during its lifetime. Moreover, bool(empty-iterable) is not False. Ditto for map() and, for instance, open(), even though in the latter case the primary object is external. -- Terry Jan Reedy [View Less]

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package based import
by Ronny Pfannschmidt May 6, 2012

May 6, 2012

Hi, this one is still prety rough (not just on the edges) after some tinkering with tools like nmp, i got the idea of package based imports the idea is to have a lookup based on package toplevel names firs, instead of just walking sys.path that way it becomes more natural for packages to be in a own dir instead of everything being merged in site-packages and of course, much less files to walk to find a particular package, since the mapping of package name to import paths is already … [View More]

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