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

Re: How to tell when a socket is closed on the other end?
by Roy Smith July 27, 2007

July 27, 2007

Jay Loden <python(a)jayloden.com> wrote: > The goal of this > portion of the test suite we are writing for the project is to determine if a > remote server is behaving properly by closing a socket from the server side > based on a client-side command. > > Really what's needed is a way to make sure the socket gets closed, and > preferably determine if it was closed from the remote end as expected. This really is way out of scope for a Python newsgroup, but what the heck. There is no way to tell through the Socket API *why* the connection was shut down, because this information isn't transmitted by the TCP protocol. All you know is that the connection did indeed get shut down. It could be because the user code at the remote end called close(). Or, it could be because the process exited (normally or abnormally) and the kernel closed the connection as part of the cleanup. All the TCP stack at this end knows is it got a packet with the FIN bit set. If you really want to know if the other end completed normally, you need to design your user-level protocol to include some "end of session" indication. For example: > bash-3.2$ telnet mx.panix.com smtp > Trying 166.84.1.72... > Connected to mx.panix.com. > Escape character is '^]'. > 220 mail1.panix.com ESMTP Postfix > helo foo > 250 mail1.panix.com > quit > 221 Bye > Connection closed by foreign host. The SMTP user-level protocol sent "221 Bye", then, my telnet client saw the actual TCP connection close, and printed the "Connection closed by foreign host" message. I know the remote end closed down the connection normally because I saw the "221" message in response to my "quit" command. > Do you > know if this is possible to determine from the client side > reliably/accurately? Would select()'s exceptional condition flag actually > indicate whether or not the root cause of the condition was a socket closed > by the remote peer? I've read through the select's manpage and I can't seem > to find a reference that indicates what the possible values are for the I/O > descriptor sets returned by select. Is there another man page, or a place in > the header file for select I can look? You need to read up about how TCP/IP works. A good place to start might be the Wikipedia article on "Transmission Control Protocol". The canonical textbook on the subject would be: Richard Stevens UNIX Network Programming, Volume 1, Second Edition: Networking APIs: Sockets and XTI Prentice Hall 1998 ISBN 0-13-490012-X

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automatic type conversion for comparison operators
by Russ July 27, 2007

July 27, 2007

I posted a message on this several days ago, but it apparently got lost in googlespace, so I'll try it again. I recently discovered a bug in my code that apparently resulted from the automatic conversion of a function pointer to an integer. Say you have a class member function called getCount(), which returns an integer. Now suppose you write something like if obj.getCount < 3: ... This is an error because the parentheses were left off. But Python somehow compares the function pointer with an integer without complaining. Unless there is a darn good reason for allowing comparisons of this type (and I can't think of one), I think Python should flag this as an Exception.

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Re: How to tell when a socket is closed on the other end?
by Josiah Carlson July 27, 2007

July 27, 2007

Jay Loden wrote: > Roy Smith wrote: >> In article <1185371863.622473.205010(a)19g2000hsx.googlegroups.com>, >> billiejoex <gnewsg(a)gmail.com> wrote: >> >>> Hi there. >>> I'm setting up test suite for a project of mine. >>> >From test suite, acting as a client, I'd like to know, in certain >>> situations, if the socket is closed on the other end or not. >>> I noticed that I can "detect" such state if a call to socket.read() >>> returns 0 but it seems a little poor to me. :-\ >>> Is there a reliable way to test such socket 'state'? >> This isn't really a Python question, it's a Berkeley Socket API question. >> You don't say, but I assume you're talking about a TCP (i.e. SOCKSTREAM) >> connection? >> >> The answer is you can use the select() system call to detect "exceptional >> conditions" on a socket. Python's select module provides this >> functionality, but to understand how to use it, you need to study the >> underlying API. > > Thanks for the interesting information and suggestion of using select(). You are correct that this is actually mostly a socket API question but pertains to Python since the code is all Python's socket and asyncore modules. It might help to step back and explain the original problem. The goal of this portion of the test suite we are writing for the project is to determine if a remote server is behaving properly by closing a socket from the server side based on a client-side command. > > Really what's needed is a way to make sure the socket gets closed, and preferably determine if it was closed from the remote end as expected. Do you know if this is possible to determine from the client side reliably/accurately? Would select()'s exceptional condition flag actually indicate whether or not the root cause of the condition was a socket closed by the remote peer? I've read through the select's manpage and I can't seem to find a reference that indicates what the possible values are for the I/O descriptor sets returned by select. Is there another man page, or a place in the header file for select I can look? Use select to determine if the socket is readable and writable. If it is, yet you can't send or receive to/from it, then it is closed. - Josiah

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Weekly Python Patch/Bug Summary
by Kurt B. Kaiser July 27, 2007

July 27, 2007

Patch / Bug Summary ___________________ Patches : 399 open ( +5) / 3836 closed ( +9) / 4235 total (+14) Bugs : 1056 open (+10) / 6776 closed ( +3) / 7832 total (+13) RFE : 263 open ( +1) / 294 closed ( +1) / 557 total ( +2) New / Reopened Patches ______________________ utilize 2.5 try/except/finally in contextlib (2007-07-19) http://python.org/sf/1757118 opened by Philip Jenvey Fix ptcp154 encoding cyrillic_asian alias (2007-07-19) http://python.org/sf/1757126 opened by Philip Jenvey Add support for seeking/writing beyond EOF to io.BytesIO (2007-07-20) CLOSED http://python.org/sf/1757683 opened by Alexandre Vassalotti struni: make test_ucn pass (2007-07-20) CLOSED http://python.org/sf/1757758 opened by Alexandre Vassalotti struni: fix str/bytes errors for test_oldmailbox (2007-07-20) CLOSED http://python.org/sf/1757774 opened by Alexandre Vassalotti setuptools support for bazaar vcs (2007-07-20) CLOSED http://python.org/sf/1757782 opened by Barry A. Warsaw struni: make test_mailbox and test_old_mailbox pass (2007-07-20) CLOSED http://python.org/sf/1757839 opened by Alexandre Vassalotti struni: Fix test_macostools (2007-07-22) CLOSED http://python.org/sf/1758570 opened by Jeffrey Yasskin pyexpat unit tests - str/uni branch (2007-07-23) CLOSED http://python.org/sf/1759016 opened by Joe Gregorio clean up Solaris port and allow C99 extension modules (2007-07-23) http://python.org/sf/1759169 opened by Zooko O'Whielacronx struni pulldom: Don't use 'types' to check strings (2007-07-24) http://python.org/sf/1759922 opened by Alexandre Vassalotti Cross Compiling Python (2007-07-25) http://python.org/sf/1760089 opened by Yegnesh ZipFile.write fails with bad modification time (2007-07-25) http://python.org/sf/1760357 opened by Grzegorz Adam Hankiewicz struni: Fix test_aepack by converting 4cc's to bytes (2007-07-26) http://python.org/sf/1761465 opened by Jeffrey Yasskin Patches Closed ______________ Show Location of Unicode Escape Errors (2007-07-18) http://python.org/sf/1755885 closed by gvanrossum Add support for seeking/writing beyond EOF to io.BytesIO (2007-07-20) http://python.org/sf/1757683 closed by gvanrossum struni: make test_ucn pass (2007-07-20) http://python.org/sf/1757758 closed by gvanrossum struni: fix str/bytes errors for test_oldmailbox (2007-07-20) http://python.org/sf/1757774 closed by avassalotti setuptools support for bazaar vcs (2007-07-20) http://python.org/sf/1757782 closed by pje struni: make test_mailbox and test_old_mailbox pass (2007-07-20) http://python.org/sf/1757839 closed by gvanrossum PEP 3123 implementation (2007-05-13) http://python.org/sf/1718153 closed by loewis struni: Fix test_macostools (2007-07-22) http://python.org/sf/1758570 closed by gvanrossum pyexpat unit tests - str/uni branch (2007-07-23) http://python.org/sf/1759016 closed by gvanrossum New / Reopened Bugs ___________________ Python 2.5.1 fails to build on AIX (2007-07-18) http://python.org/sf/1756343 opened by Tom Epperly reference count discrepancy, PyErr_Print vs. PyErr_Clear (2007-07-18) http://python.org/sf/1756389 opened by Jon Klein IDLE + BeautifulSoup = Error (2007-07-19) http://python.org/sf/1757057 opened by Tal Einat Pickle fails on BeautifulSoup's navigableString instances (2007-07-19) http://python.org/sf/1757062 opened by Tal Einat Zipfile robustness (2007-07-19) http://python.org/sf/1757072 opened by Chris Mellon Crash in PyObject_Malloc (2007-07-21) http://python.org/sf/1758146 opened by Tim Bishop Documentation of descriptors needs more detail (2007-07-22) http://python.org/sf/1758696 opened by L. Peter Deutsch unicode(None,charset) raise TypeError (2007-07-23) http://python.org/sf/1758804 opened by Guillaume subprocess.call fails with unicode strings in command line (2007-07-24) http://python.org/sf/1759845 opened by Matt poll() on cygwin sometimes fails [PATCH] (2007-07-24) http://python.org/sf/1759997 opened by Brian Warner No docs for list comparison (2007-07-25) http://python.org/sf/1760423 opened by Kent Johnson logging.FileHandler may throw exception in flush() (2007-07-25) http://python.org/sf/1760556 opened by J Livingston pickle - cannot unpickle circular deps with custom __hash__ (2007-07-26) http://python.org/sf/1761028 opened by Martin Süßkraut Bugs Closed ___________ struni: help() is broken (2007-07-11) http://python.org/sf/1751932 closed by kbk Docstring for codecs.lookup is incorrect (2007-07-15) http://python.org/sf/1754453 closed by doerwalter New / Reopened RFE __________________ splice() function for itertools (2007-07-20) CLOSED http://python.org/sf/1757395 opened by Alexander Dutton Allow opening just an editor window (2007-07-21) http://python.org/sf/1757831 opened by Tal Einat RFE Closed __________ splice() function for itertools (2007-07-20) http://python.org/sf/1757395 closed by rhettinger

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instantiate a 'classobj'
by westymatt July 27, 2007

July 27, 2007

I have a class where a parameter to its constructor is a type(param) = 'classobj'. How would I go about instantiating that given it has no constructor.

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Learning Jython?
by Matt Bitten July 27, 2007

July 27, 2007

Hi, all. I'm in a situation where I need to be writing a bunch of quick-y (hopefully) self-contained programs that anyone can run from a web page. Java applets are the obvious way to do this. However, I don't know much Java, and, frankly, right now I don't feel much like learning it. I *am* pretty good at Python, however. It looks like Jython is for me. That said, I have two questions: (1) Am I thinking straight here? Or is there some other solution that a knows-Python-but-not-Java programmer might use? (2) Assuming that I'm going with Jython, it looks like I'm not going to be able to come up with any kind of GUI without learning the Java libraries. Can someone point me to a tutorial for Everything I've found are like, "You know the Java libraries forwards and backwards; now learn to call them in Python." That's not what I need. -- Matt

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How to tell when a socket is closed on the other end?
by billiejoex July 27, 2007

July 27, 2007

Hi there. I'm setting up test suite for a project of mine. >From test suite, acting as a client, I'd like to know, in certain situations, if the socket is closed on the other end or not. I noticed that I can "detect" such state if a call to socket.read() returns 0 but it seems a little poor to me. :-\ Is there a reliable way to test such socket 'state'?

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generating objects of a type from a name.
by chris.lyon＠spritenote.co.uk July 27, 2007

July 27, 2007

I'm trying to generate visual python objects from django objects and therefore have objects called 'Ring' and 'Cylinder' as django objects and I want to create objects of those names in visual. I can cludge it in varius ways by using dir and lots of if lookups but is there a way of doing this that allows the name to generate a visual object of the appropriate name or fail nicely if the visual object doesn't exist?

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Re: SQLObject 0.9.1
by Sherm Pendley July 27, 2007

July 27, 2007

Steve Holden <steve(a)holdenweb.com> writes: > Sherm Pendley wrote: >> Steve Holden <steve(a)holdenweb.com> writes: >> >>> Sherm Pendley wrote: >>>> Gerardo Herzig <gherzig(a)fmed.uba.ar> writes: >>>> >>>>> So..at 11:23 we got version 0.7.8...at 11:30 was version 0.8.5...now >>>>> there is a 0.9.1 version?? Have a coffe dude >>>> Sounds more to me like he needs to lay off the coffee, or at least switch >>>> to decaffeinated for a while. :-) >>>> >>> Come on, give Oleg a break. He's maintaining three separate versions >>> in parallel. >> >> What part of ":-)" did you not understand? >> > The part that completely bypassed my sense of humor, I guess. Feel > free to ignore me until further notice :-) If I'm ignoring you, how will I get the notice? :-) I'll stop now... this is getting too silly for even me... sherm-- -- Web Hosting by West Virginians, for West Virginians: http://wv-www.net Cocoa programming in Perl: http://camelbones.sourceforge.net

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Re: code indentation
by Ben Finney July 27, 2007

July 27, 2007

Steve Holden <steve(a)holdenweb.com> writes: > We should be making allowances for this particular poster on account > of relative youth: I hadn't realised earlier, but we are dealing > with a fourteen-year-old. I don't believe that's true. One of the great advantages of discussion over the internet is that one's behaviour is what is judged, without necessary prejudice from one's age, skin tone, facial features, or the like. Set against the many disadvantages of internet discussion, I think "judge only on basis of behaviour" is a good default. -- \ "Pinky, are you pondering what I'm pondering?" "Well, I think | `\ so, Brain, but first you'd have to take that whole bridge | _o__) apart, wouldn't you?" -- _Pinky and The Brain_ | Ben Finney

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