🌐 Mailman 3 October 2010 - Python-list - python.org

PEP 372 -- Adding an ordered directory to collections
by Armin Ronacher Aug. 7, 2011

Aug. 7, 2011

Abstract ======== This PEP proposes an ordered dictionary as a new data structure for the ``collections`` module, called "odict" in this PEP for short. The proposed API incorporates the experiences gained from working with similar implementations that exist in various real-world applications and other programming languages. Rationale ========= In current Python versions, the widely used built-in dict type does not specify an order for the key/value pairs stored. This makes it hard to use dictionaries as data storage for some specific use cases. Some dynamic programming languages like PHP and Ruby 1.9 guarantee a certain order on iteration. In those languages, and existing Python ordered-dict implementations, the ordering of items is defined by the time of insertion of the key. New keys are appended at the end, keys that are overwritten and not moved. The following example shows the behavior for simple assignments: >>> d = odict() >>> d['parrot'] = 'dead' >>> d['penguin'] = 'exploded' >>> d.items() [('parrot', 'dead'), ('penguin', 'exploded')] That the ordering is preserved makes an odict useful for a couple of situations: - XML/HTML processing libraries currently drop the ordering of attributes, use a list instead of a dict which makes filtering cumbersome, or implement their own ordered dictionary. This affects ElementTree, html5lib, Genshi and many more libraries. - There are many ordererd dict implementations in various libraries and applications, most of them subtly incompatible with each other. Furthermore, subclassing dict is a non-trivial task and many implementations don't override all the methods properly which can lead to unexpected results. Additionally, many ordered dicts are implemented in an inefficient way, making many operations more complex then they have to be. - PEP 3115 allows metaclasses to change the mapping object used for the class body. An ordered dict could be used to create ordered member declarations similar to C structs. This could be useful, for example, for future ``ctypes`` releases as well as ORMs that define database tables as classes, like the one the Django framework ships. Django currently uses an ugly hack to restore the ordering of members in database models. - Code ported from other programming languages such as PHP often depends on a ordered dict. Having an implementation of an ordering-preserving dictionary in the standard library could ease the transition and improve the compatibility of different libraries. Ordered Dict API ================ The ordered dict API would be mostly compatible with dict and existing ordered dicts. (Note: this PEP refers to the Python 2.x dictionary API; the transfer to the 3.x API is trivial.) The constructor and ``update()`` both accept iterables of tuples as well as mappings like a dict does. The ordering however is preserved for the first case: >>> d = odict([('a', 'b'), ('c', 'd')]) >>> d.update({'foo': 'bar'}) >>> d collections.odict([('a', 'b'), ('c', 'd'), ('foo', 'bar')]) If ordered dicts are updated from regular dicts, the ordering of new keys is of course undefined again unless ``sort()`` is called. All iteration methods as well as ``keys()``, ``values()`` and ``items()`` return the values ordered by the the time the key-value pair was inserted: >>> d['spam'] = 'eggs' >>> d.keys() ['a', 'c', 'foo', 'spam'] >>> d.values() ['b', 'd', 'bar', 'eggs'] >>> d.items() [('a', 'b'), ('c', 'd'), ('foo', 'bar'), ('spam', 'eggs')] New methods not available on dict: ``odict.byindex(index)`` Index-based lookup is supported by ``byindex()`` which returns the key/value pair for an index, that is, the "position" of a key in the ordered dict. 0 is the first key/value pair, -1 the last. >>> d.byindex(2) ('foo', 'bar') ``odict.sort(cmp=None, key=None, reverse=False)`` Sorts the odict in place by cmp or key. This works exactly like ``list.sort()``, but the comparison functions are passed a key/value tuple, not only the value. >>> d = odict([(42, 1), (1, 4), (23, 7)]) >>> d.sort() >>> d collections.odict([(1, 4), (23, 7), (42, 1)]) ``odict.reverse()`` Reverses the odict in place. ``odict.__reverse__()`` Supports reverse iteration by key. Questions and Answers ===================== What happens if an existing key is reassigned? The key is not moved but assigned a new value in place. This is consistent with existing implementations and allows subclasses to change the behavior easily:: class movingcollections.odict): def __setitem__(self, key, value): self.pop(key, None) odict.__setitem__(self, key, value) What happens if keys appear multiple times in the list passed to the constructor? The same as for regular dicts: The latter item overrides the former. This has the side-effect that the position of the first key is used because the key is actually overwritten: >>> odict([('a', 1), ('b', 2), ('a', 3)]) collections.odict([('a', 3), ('b', 2)]) This behavior is consistent with existing implementations in Python, the PHP array and the hashmap in Ruby 1.9. Why is there no ``odict.insert()``? There are few situations where you really want to insert a key at an specified index. To avoid API complication, the proposed solution for this situation is creating a list of items, manipulating that and converting it back into an odict: >>> d = odict([('a', 42), ('b', 23), ('c', 19)]) >>> l = d.items() >>> l.insert(1, ('x', 0)) >>> odict(l) collections.odict([('a', 42), ('x', 0), ('b', 23), ('c', 19)]) Example Implementation ====================== A poorly performing example implementation of the odict written in Python is available: `odict.py <http://dev.pocoo.org/hg/sandbox/raw-file/tip/ odict.py>`_ The version for ``collections`` should be implemented in C and use a linked list internally. Other implementations of ordered dicts in various Python projects or standalone libraries, that inspired the API proposed here, are: - `odict in Babel`_ - `OrderedDict in Django`_ - `The odict module`_ - `ordereddict`_ (a C implementation of the odict module) - `StableDict`_ - `Armin Rigo's OrderedDict`_ .. _odict in Babel: http://babel.edgewall.org/browser/trunk/babel/util.py?rev=374#L178 .. _OrderedDict in Django: http://code.djangoproject.com/browser/django/trunk/django/utils/datastructu… .. _The odict module: http://www.voidspace.org.uk/python/odict.html .. _ordereddict: http://www.xs4all.nl/~anthon/Python/ordereddict/ .. _StableDict: http://pypi.python.org/pypi/StableDict/0.2 .. _Armin Rigo's OrderedDict: http://codespeak.net/svn/user/arigo/hack/pyfuse/OrderedDict.py Future Directions ================= With the availability of an ordered dict in the standard library, other libraries may take advantage of that. For example, ElementTree could return odicts in the future that retain the attribute ordering of the source file. Copyright ========= This document has been placed in the public domain.

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Re: Python 2.7, tkinter problem on OSX
by Jeff Hobbs July 31, 2011

July 31, 2011

On Jun 25, 1:54 am, Julien Pauty <julien.pa...(a)gmail.com> wrote: > Last version of my software relies on ttk. Under windows and linux > this is fine. But, OSX users are facing problems (I don't have access > to a Mac myself for testing...). Those with OSX 10.6 can run the > program. It seems that OSX 8.6 ships with Tk8.5. > > People with OSX 8.5 cannot run the app. I told them to install python > 2.7 which seems to be the first version on OSX to ship with Tk8.5. > However, the program still does not run. I asked a person to launch a > python 2.7 interpreter and try to import tkinter. This is an excerpt > of the output: > > from Tkinter import * > File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-tk/Tkinter.py", > line 39, in <module> > import _tkinter # If this fails your Python may not be configured for Tk > ImportError: dlopen(/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_tkinter.so, > 2): no suitable image found. Did find: > /Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/_tkinter.so: > no matching architecture in universal wrapper > > Full log is there:http://pastebin.com/vky8FbrP > > I asked a person to simply open a python2.7 shell and import Tkinter. > He got the same error. > > All of this is executed with Python 2.7rc1. Archives that are on the > ftp of python.org. > > I have seen this bughttp://bugs.python.org/issue9045, which is > related, but deals with the specificities if OSX 64bit. > > Can this problem be solved by installing Active TK 8.5 for OSX ? > > Anybody knows what is the good combination of installer / libraries to > install to run a ttk application on OSX 8.5 ? Ideally, I would like to > document the setup procedure for 8.5 users. The OS X equation is confuzzulating due to version and API changes in Mac OS X. Let's review ... OS X 10.5 ships Tcl/Tk 8.4 built 32-bit only i386+ppc using Carbon. OS X 10.6 ships Tcl/Tk 8.5 built 32/64 i386+x86_64 using Cocoa. The Cocoa port of Tk was necessary for 64-bit support, as Apple never did supply the promised 64-bit Carbon. Tk 8.5 has Cocoa as an option, and it is default in Tk 8.6. ActiveTcl 8.5 still ships as 32-bit i386+ppc Carbon because going to Cocoa also means you have to drop OS X 10.4 support (out of curiousity - does anyone care about OS X 10.4 anymore that isn't stuck on what's already installed?). 8.5 plans to do so later this year (leaving behind our OS X 10.4 brethren to older versions). ActiveTcl 8.6 (Tcl/ Tk 8.6 is in beta) already ships i386+x86_64 Cocoa. Now there is the issue that Tkinter links to a specific version of Tcl/ Tk. I am currently working on a patch that will remove this limitation (making the binary Tk version independent). So what do you do? Well, it depends on what mix you are trying to make. The easiest is to just run arch -i386 python2.7 and then it will find the compatible i386 Tk. The next release of ActivePython 2.7 (which is building i386+x86_64) will have the Tk version independence, so it could work with core Tk or AT 8.6, or 8.5 in 32-bit mode. Less confuzzulated? Jeff

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Re: dll errors in compiled python program
by alex23 May 4, 2011

May 4, 2011

Alex Hall <mehg...(a)gmail.com> wrote: > I am stumped. The compiled version of my project works on my pc, but > when I put it on a thumb drive and try it on a laptop without python > installed I get this: > ImportError: DLL load failed: The specified procedure could not be found. Are you using py2exe? If so, are you including the necessary MS runtime dll[1]? 1: http://www.py2exe.org/index.cgi/Tutorial#Step5

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Life
by saruviel April 27, 2011

April 27, 2011

Life By Daniel Daly A series of, perhaps random thoughts, or if you take the time to try and make some coherent sense of the whole, perhaps something deeper. But probably not. I was inspired to start this task by the book ‘By the Waters of Galilee’ by Fr Luke Fay of Catholic faith. I had read the first two chapters, was enjoying it, and started thinking. And I thought of a work called ‘Life’ with a similar cover to the cover of Fr Fay’s work. And the idea was simply a writing of life. Perhaps the closest thing that was to come to it was a self-help book, but in its purest form I intended it to not even be that. Perhaps philosophy, but I am not trying to be philosophical, yet it probably is philosophy, even though that is not my intent. I simply wanted to write thoughts on life, thoughts about a positive moral life, which might make it almost a religious or spiritual text, but that was not the intent. It is simply to be about life, not a novel, not a work of science, but just thoughts on life. Perhaps I should be dramatic and write lovely poetical language about the wonders of creation in true King David style. King David wrote some of the Psalms in the Holy Bible and wrote about creation a bit. At least, the psalms are recorded as being written by King David, but some people (Funk of the Historical Jesus) says no to that from memory. I suppose as this work unfolds I will write about nature, but if I was perfectly honest I am no King David. I know I really should care about the plight of the whales and that Japan are really naughty, but I think they just like whale meat, so to hell with that. How about the oil spill off the American coast. Thank God its over there is probably the bottom line for this shallow environmentalist. Anyway, enough with current affairs. Actually, no, I will write on some current affairs. I prayed, a while back, for Kevin Rudd to be Prime Minister for 21 years. I am keeping the faith on that prayer, as I am a left wing idealist. My friend Adrian Chan is not the biggest fan of politicians, but I assume they generally have good intentions, and that the demands of satisfying everyone means they aggravate a lot of people. But that is only life after all. I like listening to music. I have schizophrenia so often go on mad rampages and destroy half of my cd collection in a fit of psychosis. But psychosis affects a lot of people, so I am not alone. I was at the pool recently and I thought up some ideas for a whacky book called ‘Zen I’. The dialogue goes something like this. Zen Zen I Zen I Zen I Zen I Zen I Zen I Zen I Zen Zen Zen Zen I I I I Zen I Zen I Zen I Zen I Zen I Zen Zen Zen I Zen Zen I Zen I Zen I Zen I Zen Zen I Zen I Zen I Zen Zen I Zen I Zen Zen Zen Zen Zen Zen Zen Zen I Zen I Zen I Zen I Zen Zen I Zen I Zen I Zen Zen I Zen I Zen I Zen Zen I Zen I Zen I Zen Zen I Zen I Zen Zen Zen Zen Zen Zen Zen Zen I Zen I Zen I Zen Zen I Zen I Zen I Zen Zen I Zen I Zen Zen Zen Zen Zen Zen Zen Zen I I I I I Zen Zen I Zen Zen Zen I Zen I Zen I Zen I & so on and so forth in about 40 pages of a little hardback anthology. On the final page the last line goes: Zen Zen I Zen I Zen I Zen Zen (4XQR#) Zen I Zen I Zen I It is non stop Zen I until that line. I don’t know why, it just is. Heh. I reckon Madonna should go into the studio with a compilation of new songs written by songwriters she has hired. She should do an album a day for 3 years straight – over 1000 albums – just doing one or two takes of each song, and being filmed all the time, and with video workers simply making videos for all the songs for her from the ongoing video of her singing. Just one to two takes of the song, get the album finished, and released. And do this every day for 3 years. She can hire countless mixers and producers for the stuff and just realease a shitload of albums and videos. Overkill in the most extreme, and it really doesn’t matter if they sell that much, because there will be enough diehards who will buy all of them and she will sell tonnes. She is a hard worker, could get the job done, and it would get her the highest album sales of all time after a while. Someone with her fame and wealth could do that, and I would if I could sing, had her fame and her money. 4 + 4 = 8 8 + 8 = 16 16 + 16 = 32 Mathematics is a very entertaining subject for intellectuals. You see, intellectuals are what they call in classic American schoolyard jargon, the nerds. And the nerds like Maths, English, Science, and putting computer systems together. I hope to be a fully qualified nerd upon retirement. Think of all the dollar bills they end up getting, hey. I mean look at Billy Gates. Come up with Microsoft and what the Trillions role in. But apparently the kids don’t get a cent, and have to work for themselves. Now that’s a responsible parent. Intellectuals also like philosophy, sneering at religious people who believe in creationism (which I do), and listening to classical or alternative music and disdaining all things commercial. Heavy Metal has a similar attitude, especially back in the day. I mean, if you were a metalhead and listened to the Spice Girls it was a death penalty offense or excommunication from the headbangers ball. And if you touched Boyzone they would torture you first. Heavy Metal gurus are another bunch of pseudo-intellectual snobs. Parading their Black Sabbath albums, saying that Led Zeppelin are gods, and that such and such a band – their current fave – has reinvented heavy metal forever. They love to give ratings in heavy metal mags, but rolling stone does that too. And people honestly take an interest in these ratings. But if there is one thing I have discovered is that tastes are often very subjective – they vary widely from person to person – and an album that somebody may rate very poorly, another set of persons might enjoy tremendously. Especially poppy commercial stuff which is, again, sneered at, but which usually sells the most because the kids have enough sense to buy albums which are actually fun and not laden down with depressing angst and bullshit feelings of a so-called contemplated soul. Intelligent albums SUCK unless there is a quality of music which is attractive, melodic and memorable. Michael Jackson, for example, may be on many supposedly serious music critics hate list for his pop classic ‘Thriller’, but he is at number one because he knows what the kids like. And, funnily enough, these commercial artists who sell the most end up being the ‘Beatles’ of their era, and end up very respected. It happens to them with time and age. Mozart was an upstart to some to start with, despite his brilliance (apparently). Justin Beiber, for example, would be laughed at by a supposedly serious music critic, but the kids are not dumb. He sings a song which perfectly captures their vibe as teenagers, and is entirely appropriate and critically excellent for his target audience. He doesn’t have to produce Amy Lee or Bob Dylan. That is not his audience, and would be stupid to suggest it is. But that is what people often fall into with age – they forget the younger generation are learning, and that they too once liked such stuff. Oh, and as a confirmed Noahide, I don’t really mind if the Beatles thought they were bigger than Jesus for a while. They possibly were. When I was younger I felt it important to develop religious morality to be a perfect person. I still think that somewhat, but don’t worry as much anymore. Jesus says in the gospels ‘Be Ye Perfect as your Father in Heaven is Perfect.’ A challenge to Christians I suppose. You know, there are a hell of a lot of those 2 billion Christians (I have seen the statistics – approx 1 bill Catholics and 1 bill non- catholic Christians) who work there assess of spiritually to give Jesus a hell of a witness for the continued growth and establishment of his church of Glory. As a Noahide I view Jesus as an ambitious Jewish man, dedicated to his own glory, by and large. Now, as a Christian most of you view Jesus as God. But he isn’t. He wasn’t. And he never will be. He was just a bloke. If you don’t believe me ask God the father (ie Yahweh). These days he might possibly inform you upon the answer to that question, as he is severely pro-Israel from all my personal observations. Anyway, in current rankings of the all time most popular human beings, the rankings approximately come up like this. Number One – Jesus of Nazareth Number Two – Muhammed Number Three – Jesus mother, Mary Number Four – Buddha Number Five – Moses, I think Number Six – Apostle Paul Number Seven – The current number seven is either Taylor Swift or Miley Cyrus on current myspace page hits. This might surprise you, but this is their era and the current ‘Cult of Personality’ has HUGE fanbases. Really fucking HUGE fanbases. Anyway Miley and Taylor edge out Apostle Peter, King David, Abraham, Jacob, Adolph Hitler, and Justin Beiber for the present, but he is in the top 20 all time just about. I know that is recent, but you don’t know the power of the current fame monster, as Gaga puts it, with the ever expanding human population. Mao Tse Tung, Joseph Stalin, Karl Marx, Shakespeare, Robert Pattinson, Daniel Radcliffe, Angelina Jolie, Brad Pitt, Victoria Beckham, George Washington, J K Rowling, J R R Tolkien, Marilyn Monroe, Elvis Presley, Winston Churchill & Emma Watson are some of the very big names, likely in the top thirty to forty all time. Add on Wolfgang Amadeus Mozart and Ludwig Van Beethoven who are currently the two number ones in the classical scene – they share the honour. But number one is the carpenter from Nazareth. Still caining after 2000 years. Believe me, that takes some effort, but with the beloved ‘Cross’ at his disposal, which the faithful were around their necks with pride, the ‘Christ Child’ isn’t letting go of the number one slot any time soon. Hey, people think he is actually God himself, and that takes a lot to compete with. But somebody’s got to do it. Probably 666 will show up, some dude or dudette thinking that might work for a while, and take on the JC fellow. Bad news at the moment, though, because most humans are patently aware that the mark of the beast is bad news on judgement day. But, fucking hell, Iron Maiden released ‘Number of the Beast’ and sold a shitload. I guess the Antichrist is a keen competitor to the big fellow. You never know, he might grab the top slot for a while. What was that? Seven years says my pentecostal friend? Tribulation glory, but it won’t last? Aye Carumba. So how did Jesus get to the top slot? I have written on that before, but lets just say this much. If you can win somebody’s respect, and then start a religious cult, and then have that cult evangelize their socks off for 2000 years, it sure as hell helps. So how do you potential wannabes start a religious cult then? In Christianity every tom dick and harry started a church for a while. They were called protestants. So, to be a protestant, it is simple. Tell your current pastoral overlord to take a running jump, and start preaching those doctrines you have always wanted to preach, and evangelize. Evangelization is easy. First, do up a free website on angelfire, and post your church doctrines and teachings. Go to the library and print off 100 pages of A4 flyers, 4 flyers to a page, and cut them into 4s and make sure you put the name of the church and the website link and email address. And then, if you really want to build wonderchurch, make it your hobby to go to carparks, put flyers on car windows, and do this for 20 years. Its slow, but it works. Now, for you lateral thinkers, Christianity is basically covered. Try something new. L Ron Hubbard did. He called it scientology, and the freaks practically worship him. So go for something pseudo spiritual, a catchy name, special key teachings on enlightenment, and stick to your guns. Oh, and be dramatic. It helps. Those thoughts will do for now. I might continue this some time. Oh, and one last thing. I want to plug a few books which are truly excellent. Hugh Cook – the 10 Volume epic ‘Chronicles of an Age of Darkness’. Intense, weird, novel, original and exciting. David Eddings – The Eternal ‘Belgariad’ series. I have SEEN the Harry Potters, but Edding’s, while currently still very popular, deserves to reach J K Rowling numbers in sales. Raymond E Feist – Magician. The ultimate fantasy epic, and the first volume of the Riftwar saga. Hugely popular, and deserves to be, and really you should read it. And one last plug: My favourite all time rock album – Bon Jovi ‘New Jersey’ My favourite all time pop album – Rihanna ‘Good Girl Gone Bad’ My favourite all time Christian album – Susan Ashton ‘A Distant Call’ Daniel http://noahidebooks.angelfire.com

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GUI automation tool (windows)
by Alex Barna March 21, 2011

March 21, 2011

I know that this question has been asked for several times, but it surprises that there is no tool under very active development and the community activities are very low (mailing list posts). All the tools listed in: http://pycheesecake.org/wiki/PythonTestingToolsTaxonomy#GUITestingTools Comparing with AutoIt (www.autoitscript.com), it has tens to hundreds of posts everyday. AutoIt uses a proprietary BASIC -like language, and to be honest, I don't like it and I prefer a Pythonic solution. pywinauto seems to be the best choice but the community has been very low also. The same happens in pyguiunit, pyAA, WATSUP, all development seem to be ceased. So what happens to this field (Windows GUI automation) ?

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Print to an IPP printer (pkipplib?)
by Adam Tauno Williams March 16, 2011

March 16, 2011

I've found the module pkipplib which seems to work well for things like interrogating an IPP (CUPS) server. But is there a way to send a print job to an IPP print queue? [and no, the local system knows nothing about the print architecture so popen....lp is not an option]. I just want to send the data from a file handle to a remote IPP queue as a print job.

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Anybody use web2py?
by AppRe Godeck March 3, 2011

March 3, 2011

Just curious if anybody prefers web2py over django, and visa versa. I know it's been discussed on a flame war level a lot. I am looking for a more intellectual reasoning behind using one or the other.

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TkTable and Python 3.1
by Charles McKnight March 2, 2011

March 2, 2011

HI All, I'm fiddling around with Python and I'm trying to get tktable to work with Python 3.1 on Apple OS X 10.6 (Snow Leopard). Has anyone successfully accomplished this task, and if so, can you share how that you got it working? I've got Darwin Ports installed (current version) and I'm using Python 3.1 (ports), Tcl/Tk 8.5 (ports) and I've installed TkTable 2.10 (ports). Somehow, I've missed doing something because the Python interpreter can't seem to find the tktable module. Thanks in advance! Chuck

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Struggling to convert a mysql datetime object to a python string of a different format
by Νίκος Feb. 24, 2011

Feb. 24, 2011

Okey, i have many hours now struggling to convert a mysql datetime field that i retreive to a string of this format '%d %b, %H:%M' I google a lot but couldnt found out how to format it being a string Here si the code so far: try: cursor.execute( ''' SELECT host, hits, date FROM visitors WHERE page = '%s' ORDER BY date DESC ''' % (page) ) except MySQLdb.Error: print( "Error %d: %s" % (e.args[0], e.args[1]) ) else: #display results print ( '''<center><br><h3> ( Επισκέπτης ) ----- ( Επισκέψεις ) ----- ( Ημερομηνία ) </h3><br>''' ) print ( '''<table border = "5" cellpadding = "5">''' ) results = cursor.fetchall() for row in results: print ( ''' <tr> ''' ) for entry in row: entry = datetime.datetime.strftime( entry, '%d %b, %H:%M' ) #!!! this is wrong! print ( ''' <td> %s </td> ''' % entry ) sys.exit(0) Apart from that i don't know how iam supposed to print it, because the date string is the 3rd string in every row of the dataset. Please help me out!

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Re: Land Of Lisp is out
by namekuseijin Feb. 9, 2011

Feb. 9, 2011

On 27 out, 09:46, Xah Lee <xah...(a)gmail.com> wrote: > The Land Of Lisp is out! > > http://landoflisp.com/ > > Very well done site. > > spread the news, team lisp! > > Xah haha, I've read some of the comics before. It's truly remarkably funny, no matter the language of your choice... going well down the rabbit hole should convince one... :)

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