🌐 Mailman 3 August 2007 - Python-list - python.org

Problem with PEXPECT in Python
by Kevin Erickson June 4, 2008

June 4, 2008

Hello, I am attempting to use pexpect in python to copy files from a server using scp; the copy works however exceptions are thrown and it exits unsuccessfully. Below is the a sample code and the error: #Begin Code import sys import pexpect def GetServerData(self): foo = pexpect.spawn('scp user@server.com:/home/config/ role{/file1,/files/file2,/files/file3} /tmp') foo.expect('.*password:*') foo.sendline('server_password') foo.interact() #End Code #Begin Output file1 100% 10KB 10.0KB/s 00:01 file2 100% 946 0.9KB/s 00:00 file3 100% 1655 1.6KB/s 00:00 Traceback (most recent call last): File "mygui.py", line 6, in ? f = Form1() File "/home/Kevin/form1.py", line 41, in __init__ self.GetServerData() File "/home/Kevin/form1.py", line 84, in GetServerData foo.interact() File "/usr/lib/python2.4/site-packages/pexpect.py", line 1062, in interact selfw.__interact_copy(escape_character) File "/usr/lib/python2.4/site-packages/pexpect.py", line 1086, in __interact_copy data = self.__interact_read(self.child_fd) File "/usr/lib/python2.4/site-packages/pexpect.py", line 1075, in __interact_read return os.read(fd, 1000) OSError: [Errno 5] Input/output error #End Output The problem seems to be with the call foo.interact(); does anyone know how to fix this? Any help will be much appreciated.

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smtplib "authentication required" error
by carl.reimann＠gmail.com May 17, 2008

May 17, 2008

In using a simple smtp routine: # begin example >>> import smtplib >>> server = smtplib.SMTP('outgoing.verizon.net') >>> server.sendmail('my(a)address.net', 'another(a)address.net', """To: another(a)address.net From: my(a)address.net Subject: Shakespeare Quote Tis like the breath of an unfeed lawyer... """) >>> server.quit() # end example I find the following error: raise SMTPSenderRefused(code, resp, from_addr) smtplib.SMTPSenderRefused: (550, '5.7.1 Authentication Required', 'myuserid(a)verizon.net') I have attempted to incorporate into the interactive session: server.login = ('userid', 'password') # the same ones I use in my email program But I get the same error result. My objective is to have a simple way to send email from the command line. To do this I will write a script which can read in a file and send it to the address on top of the file. What is the procedure for authentication? Using the KMail email program (Linux, KDE desktop), I send mail through my Verizon account. Under the Configure KMail / Accounts / Modify Account / Extras tab, I clicked "Check what the server supports" and it came back 'no encryption' and 'cleartext'. So it doesn't seem that it would involve complex procedures. Any help welcome.

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Why can't timedeltas be divided?
by Dan Bishop April 26, 2008

April 26, 2008

If I try to write something like: num_weeks = time_diff / datetime.timedelta(days=7) I get: TypeError: unsupported operand type(s) for /: 'datetime.timedelta' and 'datetime.timedelta' Of course, one could extend the timedelta class to implement division, def _microseconds(self): return (self.days * 86400 + self.seconds) * 1000000 + self.microseconds def __truediv__(self, other): if isinstance(other, datetime.timedelta): return self._microseconds() / other._microseconds() else: return datetime.timedelta(0, 0, self._microseconds() / other) def __floordiv__(self, other): if isinstance(other, datetime.timedelta): return self._microseconds() // other._microseconds() return NotImplemented but why is a basic arithmetic operation missing from the standard datetime module?

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[ANN] Python courses this Fall
by wesley chun April 1, 2008

April 1, 2008

Folks, I'd like to announce my final Python courses for 2007: Need to get up-to-speed with Python as quickly as possible? Come join me, Wesley Chun, author of Prentice-Hall's well-received "Core Python Programming," for another set of courses this Fall in beautiful Northern California! This will be the final set for 2007... if you miss these, you'll have to wait until next year. I look forward to meeting you! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - (COMPREHENSIVE) INTRODUCTION TO PYTHON: Mon-Wed, 2007 Oct 8-10 This is course is meant for those new to Python and/or want to get more in-depth formal training. We will immerse you in the world of Python in only a few days. We will show you more than just its syntax (which you don't really need a book to learn, right?). Knowing more about how Python works under the covers, including the relationship between data objects and memory management, will make you a much more effective Python programmer coming out of the gate. 3 hands-on labs each day will help hammer the concepts home. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - INTERNET PROGRAMMING WITH PYTHON: Sat, 2007 Oct 13 This 1-day course will introduce current Python programmers to 3 distinct areas of Internet programming, each in self-contained modules with a set of lab exercises following each lecture topic: Network Programming using Sockets -- Underneath all of today's network protocols, i.e., HTTP, FTP, RDBMS, IM, e-mail, etc., lies the main communication mechanism, sockets. Here, we introduce client/server architecture and how to program sockets using Python. Internet Client Programming -- One level above the socket layer are well-known Internet protocols such as FTP, NNTP, POP3, and SMTP. In this section, we learn how to create Internet clients of these protocols to transfer files, send and receive e-mail, and read Usenet newsgroup postings. Web/CGI Programming -- Yes, pure CGI is "sooo yesterday," but before you jump on all the web framework bandwagons, it's a good idea to learn basics and the basis of how all web servers deliver dynamic content back to the client browser so that you can appreciate all the work that is done on your behalf by a more fully-featured frame- work. Time-permitting, we will also give a high-level overview of one of the more popular Python web frameworks, Django. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - WHERE: near the San Francisco Airport (SFO/San Bruno), CA, USA WEB: http://cyberwebconsulting.com (click "Python Training") LOCALS: easy freeway (101/280/380) with lots of parking plus public transit (BART and CalTrain) access via the San Bruno stations, easily accessible from all parts of the Bay Area VISITORS: free shuttle to/from the airport, free high-speed internet, free breakfast and regular evening receptions; fully-equipped suites See website for costs, venue info, and registration. Discounts are available for multiple registrations as well as for teachers/students. Hope to see you there! -- wesley - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - "Core Python Programming", Prentice Hall, (c)2007,2001 http://corepython.com wesley.j.chun :: wescpy-at-gmail.com python training and technical consulting cyberweb.consulting : silicon valley, ca http://cyberwebconsulting.com

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Python re expr from Perl to Python
by Michael M. Feb. 25, 2008

Feb. 25, 2008

In Perl, it was: ## Example: "Abc | def | ghi | jkl" ## -> "Abc ghi jkl" ## Take only the text betewwn the 2nd pipe (=cut the text in the 1st pipe). $na =~ s/\ \|(.*?)\ \|(.*?)\ \|/$2/g; ## -- remove [ and ] in text $na =~ s/\[//g; $na =~ s/\]//g; # print "DEB: \"$na\"\n"; # input string na="Abc | def | ghi | jkl [gugu]" # output na="Abc ghi jkl gugu" How is it done in Python?

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do design patterns still apply with Python?
by John Salerno Jan. 26, 2008

Jan. 26, 2008

Since Python does so many things different, especially compared to compiled and statically typed languages, do most of the basic design patterns still apply when writing Python code? If I were to read a design pattern book (such as Head First Design Patterns), could I apply their Java examples to Python easily enough, or does Python require a different perspective when applying patterns?

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TopSort in Python?
by Tim Peters Jan. 20, 2008

Jan. 20, 2008

From: "Tim Peters" <tim_one(a)email.msn.com> [Dinu C. Gherman] > Does anybody have a simple-minded-but-working full-Python > implementation of topsort, the topological sorting algorithm? > Or maybe *any* topsort? I remember only one such algorithm... > python.org/search doesn't reveal any... Searching for "topological" instead turns up two hits there, a few more on DejaNews. Apparently "the std" algorithm I posted years ago predates DejaNews, though. So here's a fancier version ... check-out-aaron's-kjbuckets-too-ly y'rs - tim # topsort takes a list of pairs, where each pair (x, y) is taken to # mean that x <= y wrt some abstract partial ordering. The return # value is a list, representing a total ordering that respects all # the input constraints. # E.g., # topsort( [(1,2), (3,3)] ) # may return any of (but nothing other than) # [3, 1, 2] # [1, 3, 2] # [1, 2, 3] # because those are the permutations of the input elements that # respect the "1 precedes 2" and "3 precedes 3" input constraints. # Note that a constraint of the form (x, x) is really just a trick # to make sure x appears *somewhere* in the output list. # # If there's a cycle in the constraints, say # topsort( [(1,2), (2,1)] ) # then CycleError is raised, and the exception object supports # many methods to help analyze and break the cycles. This requires # a good deal more code than topsort itself! from exceptions import Exception class CycleError(Exception): def __init__(self, sofar, numpreds, succs): Exception.__init__(self, "cycle in constraints", sofar, numpreds, succs) self.preds = None # return as much of the total ordering as topsort was able to # find before it hit a cycle def get_partial(self): return self[1] # return remaining elt -> count of predecessors map def get_pred_counts(self): return self[2] # return remaining elt -> list of successors map def get_succs(self): return self[3] # return remaining elements (== those that don't appear in # get_partial()) def get_elements(self): return self.get_pred_counts().keys() # Return a list of pairs representing the full state of what's # remaining (if you pass this list back to topsort, it will raise # CycleError again, and if you invoke get_pairlist on *that* # exception object, the result will be isomorphic to *this* # invocation of get_pairlist). # The idea is that you can use pick_a_cycle to find a cycle, # through some means or another pick an (x,y) pair in the cycle # you no longer want to respect, then remove that pair from the # output of get_pairlist and try topsort again. def get_pairlist(self): succs = self.get_succs() answer = [] for x in self.get_elements(): if succs.has_key(x): for y in succs[x]: answer.append( (x, y) ) else: # make sure x appears in topsort's output! answer.append( (x, x) ) return answer # return remaining elt -> list of predecessors map def get_preds(self): if self.preds is not None: return self.preds self.preds = preds = {} remaining_elts = self.get_elements() for x in remaining_elts: preds[x] = [] succs = self.get_succs() for x in remaining_elts: if succs.has_key(x): for y in succs[x]: preds[y].append(x) if __debug__: for x in remaining_elts: assert len(preds[x]) > 0 return preds # return a cycle [x, ..., x] at random def pick_a_cycle(self): remaining_elts = self.get_elements() # We know that everything in remaining_elts has a predecessor, # but don't know that everything in it has a successor. So # crawling forward over succs may hit a dead end. Instead we # crawl backward over the preds until we hit a duplicate, then # reverse the path. preds = self.get_preds() from random import choice x = choice(remaining_elts) answer = [] index = {} in_answer = index.has_key while not in_answer(x): index[x] = len(answer) # index of x in answer answer.append(x) x = choice(preds[x]) answer.append(x) answer = answer[index[x]:] answer.reverse() return answer def topsort(pairlist): numpreds = {} # elt -> # of predecessors successors = {} # elt -> list of successors for first, second in pairlist: # make sure every elt is a key in numpreds if not numpreds.has_key(first): numpreds[first] = 0 if not numpreds.has_key(second): numpreds[second] = 0 # if they're the same, there's no real dependence if first == second: continue # since first < second, second gains a pred ... numpreds[second] = numpreds[second] + 1 # ... and first gains a succ if successors.has_key(first): successors[first].append(second) else: successors[first] = [second] # suck up everything without a predecessor answer = filter(lambda x, numpreds=numpreds: numpreds[x] == 0, numpreds.keys()) # for everything in answer, knock down the pred count on # its successors; note that answer grows *in* the loop for x in answer: assert numpreds[x] == 0 del numpreds[x] if successors.has_key(x): for y in successors[x]: numpreds[y] = numpreds[y] - 1 if numpreds[y] == 0: answer.append(y) # following "del" isn't needed; just makes # CycleError details easier to grasp del successors[x] if numpreds: # everything in numpreds has at least one predecessor -> # there's a cycle if __debug__: for x in numpreds.keys(): assert numpreds[x] > 0 raise CycleError(answer, numpreds, successors) return answer

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subprocess "handle is invalid" error
by Grant Edwards Jan. 10, 2008

Jan. 10, 2008

I'm trying to use the py-gnuplot module on windows, and have been unable to get it to work reliably under Win2K and WinXP. By default, it uses popen(gnuplotcmd,'w'), but in some situations that consistently gets an "invalid operand" IOError when write() is called on the pipe. So I switched to subprocess. It works fine when executed "normally" (e.g. "python progname.py"), but when bundled by py2exe, it always does this: Traceback (most recent call last): File "surfedit.py", line 28, in ? File "Gnuplot\_Gnuplot.pyc", line 178, in __init__ File "Gnuplot\gp_win32.pyc", line 117, in __init__ File "subprocess.pyc", line 533, in __init__ File "subprocess.pyc", line 607, in _get_handles File "subprocess.pyc", line 634, in _make_inheritable WindowsError: [Errno 6] The handle is invalid How does one troubleshoot errors that happen three layers deep in the subprocess module? -- Grant Edwards grante Yow! I'm a fuschia bowling at ball somewhere in Brittany visi.com

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Re: PyImport_ImportModule/embedding: surprising behaviors
by Ziga Seilnacht Oct. 25, 2007

Oct. 25, 2007

David Abrahams wrote: > I'm seeing highly surprising (and different!) behaviors of > PyImport_ImportModule on Linux and Windows when used in a program with > python embedding. > > On Linux, when attempting to import a module xxx that's in the current > directory, I get > > ImportError: No module named xxx > > I can work around the problem by setting > > PYTHONPATH=. Python puts the current directory in sys.path only if it can't determine the directory of the main script. There was a bug on Windows that always added current directory to sys.path, but it was fixed in Python 2.5. This is documented in the library reference: http://docs.python.org/lib/module-sys.html#l2h-5149 > On Windows, I get: > > 'import site' failed; use -v for traceback > > I can work around the problem by setting PYTHONPATH to point to the > python library directory: > > set PYTHONPATH=c:\Python25\Lib This happens because Python calculates the initial import path by looking for an executable file named "python" along PATH. You can change this by calling Py_SetProgramName(filename) before calling Py_Initialize(). This is documented in API reference manual: http://docs.python.org/api/embedding.html That page also describes a few hooks that you can overwrite to modify the initial search path. They are described in more detail on this page: http://docs.python.org/api/initialization.html HTH, Ziga

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Python script for mobile platforms -- suggested?
by Robert Dailey Oct. 19, 2007

Oct. 19, 2007

Hi, I'm currently developing a game for a cell phone. The game has a GUI system that's currently using XML to define the individual menus. Basically this means that for every single menu the user goes to, it loads and parses an XML file. Would using Python Script instead of XML be a reasonable replacement, or would it be even slower? I've read various articles online but I'm still curious to hear what everyone has to say here. Thanks.

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