🌐 Mailman 3 July 2011 - Python-list - python.org

HOWTO: Parsing email using Python part1
by aspineux July 3, 2011

July 3, 2011

Hi I have written an article about parsing email using Python. The article is at http://blog.magiksys.net/Parsing-email-using-python-header and the full content is here. Hope this help someone. Regards. A lot of programs and libraries commonly used to send emails don't comply with RFC. Ignore such kind of email is not an option because all mails are important. It is important to do it best when parsing emails, like does most popular MUA. Python's has one of the best library to parse emails: the email package. First part, how to decode mails header Regarding RFC 2047 non ascii text in the header must be encoded. RFC 2822 make the difference between different kind of header. *text field like Subject: or address fields like To:, each with different encoding rules. This is because RFC 822 forbids the use of some ascii characters at some place because they have some meaning, but these ascii characters can be used when they are encoded because the encoded version don't disturb the parsing of string. Python provides email.Header.decode_header() for decoding header. The function decode each atom and return a list of tuples ( text, encoding ) that you still have to decode and join to get the full text. This is done in my getmailheader() function. For addresses, Python provides email.utils.getaddresses() that split addresses in a list of tuple ( display-name, address ). display-name need to be decoded too and addresses must match the RFC2822 syntax. The function getmailaddresses() does all the job. Here are the functions in actions. import re import email from email.Utils import parseaddr from email.Header import decode_header # email address REGEX matching the RFC 2822 spec # from perlfaq9 # my $atom = qr{[a-zA-Z0-9_!#\$\%&'*+/=?\^`{}~|\-]+}; # my $dot_atom = qr{$atom(?:\.$atom)*}; # my $quoted = qr{"(?:\\[^\r\n]|[^\\"])*"}; # my $local = qr{(?:$dot_atom|$quoted)}; # my $domain_lit = qr{\[(?:\\\S|[\x21-\x5a\x5e-\x7e])*\]}; # my $domain = qr{(?:$dot_atom|$domain_lit)}; # my $addr_spec = qr{$local\@$domain}; # # Python translation atom_rfc2822=r"[a-zA-Z0-9_!#\$\%&'*+/=?\^`{}~|\-]+" atom_posfix_restricted=r"[a-zA-Z0-9_#\$&'*+/=?\^`{}~|\-]+" # without '!' and '%' atom=atom_rfc2822 dot_atom=atom + r"(?:\." + atom + ")*" quoted=r'"(?:\\[^\r\n]|[^\\"])*"' local="(?:" + dot_atom + "|" + quoted + ")" domain_lit=r"\[(?:\\\S|[\x21-\x5a\x5e-\x7e])*\]" domain="(?:" + dot_atom + "|" + domain_lit + ")" addr_spec=local + "\@" + domain email_address_re=re.compile('^'+addr_spec+'$') raw="""MIME-Version: 1.0 Received: by 10.229.233.76 with HTTP; Sat, 2 Jul 2011 04:30:31 -0700 (PDT) Date: Sat, 2 Jul 2011 13:30:31 +0200 Delivered-To: alain.spineux(a)gmail.com Message-ID: <CAAJL_=kPAJZ=fryb21wBOALp8-XOEL- h9j84s3SjpXYQjN3Z3A(a)mail.gmail.com> Subject: =?ISO-8859-1?Q?Dr.=20Pointcarr=E9?= From: Alain Spineux <alain.spineux(a)gmail.com> To: =?ISO-8859-1?Q?Dr=2E_Pointcarr=E9?= <alain.spineux(a)gmail.com> Content-Type: multipart/alternative; boundary=000e0cd68f223dea3904a714768b --000e0cd68f223dea3904a714768b Content-Type: text/plain; charset=ISO-8859-1 -- Alain Spineux --000e0cd68f223dea3904a714768b Content-Type: text/html; charset=ISO-8859-1 -- Alain Spineux --000e0cd68f223dea3904a714768b-- """ def getmailheader(header_text, default="ascii"): """Decode header_text if needed""" try: headers=decode_header(header_text) except email.Errors.HeaderParseError: # This already append in email.base64mime.decode() # instead return a sanitized ascii string return header_text.encode('ascii', 'replace').decode('ascii') else: for i, (text, charset) in enumerate(headers): try: headers[i]=unicode(text, charset or default, errors='replace') except LookupError: # if the charset is unknown, force default headers[i]=unicode(text, default, errors='replace') return u"".join(headers) def getmailaddresses(msg, name): """retrieve From:, To: and Cc: addresses""" addrs=email.utils.getaddresses(msg.get_all(name, [])) for i, (name, addr) in enumerate(addrs): if not name and addr: # only one string! Is it the address or is it the name ? # use the same for both and see later name=addr try: # address must be ascii only addr=addr.encode('ascii') except UnicodeError: addr='' else: # address must match adress regex if not email_address_re.match(addr): addr='' addrs[i]=(getmailheader(name), addr) return addrs msg=email.message_from_string(raw) subject=getmailheader(msg.get('Subject', '')) from_=getmailaddresses(msg, 'from') from_=('', '') if not from_ else from_[0] tos=getmailaddresses(msg, 'to') print 'Subject: %r' % subject print 'From: %r' % (from_, ) print 'To: %r' % (tos, ) And the ouput: Subject: u'Dr. Pointcarr\xe9' From: (u'Alain Spineux', 'alain.spineux(a)gmail.com') To: [(u'Dr. Pointcarr\xe9', 'alain.spineux(a)gmail.com')]

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Nested/Sub Extensions in Python
by H Linux July 3, 2011

July 3, 2011

Dear all, I am currently fighting with a problem writing a set of Python extensions in C. I want to structure the whole package (here called smt for sub-module test) into different sub-modules, e.g. according to this layout: smt.foo.func() I can only build a module >import foo >print foo.func(1,2) Once I try to nest this, I cannot get the module to load anymore: >import smt.bar Traceback (most recent call last): File "<stdin>", line 1, in <module> ImportError: No module named bar I have found the following hints on the web: http://stackoverflow.com/questions/1681281/nested-python-c-extensions-modul… I have also found that XEN has a python module which does this, but http://www.google.de/codesearch#4Wqoij9clTg/tools/python/setup.py Still I am unable to get this to work. What am I missing? In case it matters, this is on Ubuntu10.4/Python2.6.5 Below are listings from my source files. Thanks in advance for any help, Hartwig 1. setup.py: from distutils.core import setup, Extension PACKAGE_NAME = 'smt' setup( name = PACKAGE_NAME, version = '0.1', author = 'Myself', packages = [PACKAGE_NAME], ext_modules = [ Extension('foo', ['src/foo.c']), Extension('smt.bar', ['src/bar.c']) ] ) 2. src/bar.c #include <Python.h> static PyObject* bar_func(PyObject *self, PyObject *args) { PyObject *a, *b; if (!PyArg_UnpackTuple(args, "func", 2, 2, &a, &b)) { return NULL; } return PyNumber_Add(a, b); } static PyMethodDef bar_methods[] = { {"func", bar_func, METH_VARARGS, NULL}, {NULL, NULL} }; PyMODINIT_FUNC initbar(void) { Py_InitModule("smt.bar", bar_methods); } 3. src/foo.c #include <Python.h> static PyObject* foo_func(PyObject *self, PyObject *args) { PyObject *a, *b; if (!PyArg_UnpackTuple(args, "func", 2, 2, &a, &b)) { return NULL; } return PyNumber_Add(a, b); } static PyMethodDef foo_methods[] = { {"func", foo_func, METH_VARARGS, NULL}, {NULL, NULL} }; PyMODINIT_FUNC initfoo(void) { Py_InitModule("foo", foo_methods); } 4. Code Layout: ├── setup.py ├── smt │ └── __init__.py └── src ├── bar.c └── foo.c

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Re: Why won't this decorator work?
by Gregory Ewing July 3, 2011

July 3, 2011

Ian Kelly wrote: > If it's not a callable, then the result > will just be that something non-callable is bound to the "roll_die" > name -- which could be useful, but is probably a bad idea in general. There are legitimate uses -- for example, the following is a convenient way of creating a read-only property: @property def foo(self): return self.calculate_value_of_foo() -- Greg

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Re: The end to all language wars and the great unity API to come!
by rantingrick July 3, 2011

July 3, 2011

On Jul 2, 10:14 pm, Chris Angelico <ros...(a)gmail.com> wrote: > I specced up "the perfect language" a while ago. It gave you a clean > slate with no facilities but one: Define Operator. [...] That was some great satire :) but the last thing we need is users with that much power. Take the example of Ruby allowing you to redefine built in types... disastrous. I understand that freedom is good however unbridled freedom is a recipe for disaster.

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Re: The end to all language wars and the great unity API to come!
by Gregory Ewing July 3, 2011

July 3, 2011

Chris Angelico wrote: > Your proposed "Unity API" (which I assume has nothing to do with Natty > Narwhal's preferred interface) already exists. It's the C language. Or maybe GObject Introspection is closer to what you have in mind? A library that supports GI advertises enough information about itself for dynamic languages such as Python and Ruby to automatically construct fairly object-oriented interfaces. It's not perfect, though; for example, the old PyGtk module used to let you access most of what Gtk calls "properties" using Python attribute access, but with GI you have to call the get_property and set_property functions. Also you often can't just call a class to construct an object, but have to call a separate constructor function instead. -- Greg

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The end to all language wars and the great unity API to come!
by rantingrick July 3, 2011

July 3, 2011

Hello fellow programmers, scripters, hackers, and debutantes. I have cross posted this thread to three groups that i believe need to unite under the flag of unity for the benefit of all. Because when we unite we not only help ourselves, we promote freedom. In the next few paragraphs i will expose the source of this problem and propose a viable solution for how WE can solve the problem! It saddens me when i see API's that don't include at least three language choices. No *one* language is going to please the masses. I understand *WHY* this happens however it should never, *EVER* happen and i cannot lay blame solely on application developers because "we" have failed to provide them NOT ONLY with a unifying API model, but also our respective "plugin" interfaces to that unifying model. Yes folks "WE" are to blame for this dilemma. Who is "we" exactly? "We" is any language community who's language exhibits the traits of an API scripting language. For me that group includes (at the minimum) Python, Ruby, Basic, Perl, JavaScript, and whoever else wants to be part of this group. Everyone knows that no one language can solve all problems. And likewise everyone knows that even when two languages are similar (in few ways, or in many ways) people are always going to draw lines in the sand and prefer to use one language over another. It is natural to simply ones working environment. How many of you folks speak English on Mondays and Mandarin on Tuesdays and Spanish on Wednesdays and French on Thursdays and Bulgarian on Fridays and Pig Latin on Saturdays and Orc on Sundays? Anyone? Why i am not surprised! But we do this very same asinine thing on a daily basis whist jumping through the productivity limiting hoops. The stench of which rises up from every community of language developers in the world. We have not only created a mutual cess pool of laziness and selfishness , we are wallowing and rooting around in it completely oblivious of our collectively bombastic stupidity. So i ask yous, why should we continue to propagate hateful feelings, or have some among us feel left out because their favorite language is not included as an alternative in the API they are using at the time? Why should i need to switch back and forth between multiple languages, multiple syntaxes, multiple editors, multiple help files, multiple API help files, and suffer multiple headaches just because the status quo is to be selfish and not care about the greater "Programming Community". "Community". Hmm, now that is a word that can be applied in many dimensions. The "Python Community" is a community that inherits from the "Programming Community"... as is the "Ruby Community" and the "JavaScript Community" and so on and so forth. We are naturally good at taking care of our immediate community but for the community once removed we are failing miserably! And this community is the most important community of all! When we damage the programming community we damage ourselves and everyone else! [Thought Exercise] Just imagine for a second if automobiles where engineered the way programming languages are currently engineered. But wait! Before we jump into insightful analyolgies we must first understand why the automobile is such a versatile feat of engineering. The automobile -- no matter how large or small, not matter if truck or car or motorcycle or moped-- is designed to interface with a system... the "highway" system. The user of an automobile is never restricted from driving his favorite car. He is always happy because he is free. Free to choose and free to be.... HOWEVER NOT THE CASE WITH APIs! For API's we have just tossed freedom to the wind fro the sake of selfishness. We would have multiple language developers creating languages without any regard for a language independent system to plug said language into. But i am here to tell you that we can be different with our language style and still promote the freedom to choose. The tool is NOT Ruby or Python or whatever. The tool is software which manifests itself as "ones" and "zeros". Layers of abstraction that all compile to the same base units... 1's and 0's. Languages are abstractions of ones and zeros. Languages are NOT tools. Therefore we all have a vested interest in a unifying API. Well some would say... " it is up to the developer of an application what language they choose"... and this is true. But i say they can choose to allow the users to choose thereby maintaining not only a happier user base, but a more productive one as well. When are we going to see the light and start unifying our collective differences into a singular plug and play API and allowing the user of "our" abstraction language, "our" for loop, or "our" version of stdout.write the ultimate of all choices... the choice of FREEDOM. for danish inspirations see: http://wiki.services.openoffice.org/wiki/Uno Thank You

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Re: The end to all language wars and the great unity API to come!
by rantingrick July 3, 2011

July 3, 2011

On Jul 2, 8:49 pm, Chris Angelico <ros...(a)gmail.com> wrote: > On Sun, Jul 3, 2011 at 11:43 AM, rantingrick <rantingr...(a)gmail.com> wrote: > > I mean what is the point of having two languages with the exact same > > syntax? > > > Ruby: print 'blah' > > Python: print 'blah' > > > Ruby: for x in blah: blah_blah_blah > > Python: for x in blah: blah_blah_blah > > > WHAT? > > What's the point of having fifty languages in which "x+y" is an > expression whose value is the sum of x and y? Let's ditch 'em all and > just use one language, since _obviously_ the languages have the exact > same syntax. It seem ludicrous at first glance but it is true! We have to much re- inventing going on! > Common syntax is an aid to learning. It means you can transfer > knowledge from one language to another. It doesn't make either > useless. Why do you constantly propagate multiplicity? Why do you feel that we need 100 or so languages when about three would cover everything? Sure people are free to create whatever Frankenstein language they want in the confines of their hobby time, but we need standards and we need them NOW. We want the world and we want it now! http://www.youtube.com/watch?v=xkp8fNODegU&feature=player_detailpage#t=472s

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Re: web browsing short cut
by Chris Rebert July 3, 2011

July 3, 2011

> On Sat, Jul 2, 2011 at 7:10 PM, Chris Rebert <clp2(a)rebertia.com> wrote: >> On Sat, Jul 2, 2011 at 6:21 PM, Dustin Cheung <dustin299(a)gmail.com> wrote: >> > Hey guys, >> > I am new to python. I want to make a shortcut that opens my websites >> > and re-sizes them to >> > point to to the right direction? Here is what I came up with so far.. >> >> The window positioning+resizing bit will likely require using >> platform-specific APIs. Since you appear to be on Windows, the >> relevant library would be pywin32 (http://pypi.python.org/pypi/pywin32 >> ). You would use it to invoke some COM API that does window >> positioning+resizing. I am unable to give more details as I'm on a >> Mac. >> >> Sidenote: Have you tried Firefox's "Bookmark All Tabs" feature? On Sat, Jul 2, 2011 at 7:34 PM, Dustin Cheung <dustin299(a)gmail.com> wrote: > Hey, > Thanks for showing me to pywin32. I'll look into it and see what i can come > up with. Also, I haven't tried the Firefox feature. I thought the bookmark > all feature only saved one browser with multiple tabs. Correct. I don't know your precise use-case and thought that this could possibly be sufficient but significantly less complicated. > I'm sorry but this > might be a stupid question but was do you mean by COM API? COM as in: http://en.wikipedia.org/wiki/Component_Object_Model API as in a programming interface: http://en.wikipedia.org/wiki/Application_programming_interface It's my understanding that most Windows GUI automation stuff tends to involve using COM. Again, I don't know specifics, I've just followed other Windows-specific posts on the mailinglist. Cheers, Chris

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Anyone want to critique this program?
by John Salerno July 3, 2011

July 3, 2011

Just thought I'd post this in the event anyone has a few spare minutes and feels like tearing apart a fairly simple attempt to write a game. :) I'll paste the exercise I was working on first, although I think it was meant to be an exercise in how to use lists. I went way beyond that, so maybe my program is overly complicated. It works, though, so that's a plus! The main questions I had about it are at the bottom, after the code. ---------- Snakes and Ladders can be a fun game for kids to play but you realize when you get older that the players actually have no choices at all. To illustrate just how little input the players have I want you to make a computer program that allows two players to play snakes and ladders on the board given. The rules of the game are simple. On each player's turn they roll one six sided die and move ahead that many squares. If they end their move at the base of a ladder then they automatically climb to the top of the ladder. If they end their move at the end of a snake they automatically slide down to its head. To win the game you must be the first player to land on the last square. If you are near the end and your roll would cause you to go past the end square you don't move for that turn. Your computerized version will look something like: Player 1 hit enter to roll You rolled: 3 You are at spot 3 Player 2 hit enter to roll You rolled: 6 You climbed a ladder You are at spot 17 although you can write this program without using lists, you should ask yourself how you can use lists to encode where the snakes and ladders are. ----------------- (I changed snakes to chutes, and I didn't paste in the game board picture. Just trust that the dictionary of lists in the beginning of the program is accurate, and that each set of numbers represents first the space you land on, and second the space you slide or climb to, e.g. [30, 35] means you landed on 30, and as a result of landing on a ladder space, you climbed up to space 35.) ------------------------------- import random game_information = '***Chutes and Ladders***\nUp to four (4) players may play.\n'\ 'There are 90 spaces on the board. '\ 'The player to reach space 90 first wins.' separator = '-' * 20 spaces = [None] * 90 c_l_spaces = {r'slid down a chute \\': [[14, 3], [20, 15], [39, 33], [66, 53], [69, 58], [79, 67], [84, 71], [88, 36]], 'climbed up a ladder |=|': [[6, 17], [24, 26], [30, 44], [49, 62], [82, 86]]} class Player: def __init__(self, number): self.number = number self.space = 0 def move(self, roll): global spaces if (self.space + roll) > 90: return (1, 'Your roll would move you off the game board. '\ 'You remain at space {0}.'.format(self.space)) elif (self.space + roll) == 90: return (0, 'You moved to the last space. You won the game!') else: self.space += roll try: space_type = spaces[self.space - 1][0] self.space = spaces[self.space - 1][1] except TypeError: return (1, 'You moved to space {0}.'.format(self.space)) else: return (1, 'You {0} to space {1}!'.format(space_type, self.space)) def roll_die(): roll = random.randint(1, 6) print('You rolled {0}.'.format(roll)) return roll def populate_game_board(): global spaces for key, values in c_l_spaces.items(): for space in values: spaces[space[0] - 1] = [key, space[1]] def initialize_players(): while True: try: num_players = int(input('Enter the number of players (0 to exit): ')) except ValueError: print('You have entered an invalid response.\n') else: if num_players == 0: print('You have quit the game.') return elif 1 <= num_players <= 4: break elif (num_players < 0) or (num_players > 4): print('You have entered an invalid number of players. \n') players = [] for num in range(num_players): players.append(Player(num + 1)) return players def start_game(players): game = 1 while game: for player in players: print('\n***Player {0}***'.format(player.number)) print('You are currently on space {0}.'.format(player.space)) game_update = player.move(roll_die()) print(game_update[1]) print(separator, end='') if game_update[0] == 0: game = 0 break if game: input('\nPress Enter for the next turn.') def initialize_game(): global game_information print(game_information) players = initialize_players() if players: populate_game_board() start_game(players) if __name__ == '__main__': initialize_game() -------------------------- My questions: 1. Are the functions I made necessary? Do they do enough or too much? 2. Is there a better way to implement the players than as a class? 3. Is there a better way to handle all the print calls that the program makes? 4. Are my try/except blocks used appropriately? Any other comments would be appreciated too! Thanks!

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Inexplicable behavior in simple example of a set in a class
by Saqib Ali July 3, 2011

July 3, 2011

I have written two EXTREMELY simple python classes. One class (myClass1) contains a data attribute (myNum) that contains an integer. The other class (myClass2) contains a data attribute (mySet) that contains a set. I instantiate 2 instances of myClass1 (a & b). I then change the value of a.myNum. It works as expected. Then I instantiate 2 instances of myClass2 (c & d). I then change the value of c.mySet. Bizarrely changing the value of c.mySet also affects the value of d.mySet which I haven't touched at all!?!?! Can someone explain this very strange behavior to me? I can't understand it for the life of me. Please see below the source code as well as the output. -------------------------- SOURCE CODE ------------------------------ import sets class myClass1: myNum = 9 def clearNum(self): self.myNum = 0 def __str__(self): return str(self.myNum) class myClass2: mySet = sets.Set(range(1,10)) def clearSet(self): self.mySet.clear() def __str__(self): return str(len(self.mySet)) if __name__ == "__main__": # Experiment 1. Modifying values of member integers in two different instances of a class # Works as expected. a = myClass1() b = myClass1() print "a = %s" % str(a) print "b = %s" % str(b) print "a.clearNum()" a.clearNum() print "a = %s" % str(a) print "b = %s\n\n\n" % str(b) # Experiment 2. Modifying values of member sets in two different instances of a class # Fails Unexplicably. d is not being modified. Yet calling c.clearSet() seems to change d.mySet's value c = myClass2() d = myClass2() print "c = %s" % str(c) print "d = %s" % str(d) print "c.clearSet()" c.clearSet() print "c = %s" % str(c) print "d = %s" % str(d) -------------------------- OUTPUT ------------------------------ > python.exe myProg.py a = 9 b = 9 a.clearNum() a = 0 b = 9 c = 9 d = 9 c.clearSet() c = 0 d = 0

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