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  • how to import Java class with Python using Eclipse?

    - by JChao
    Hi, I'm trying to write Jython where the Python file imports classes from Java I'm using Eclipse with PyDev. My Python code looks like: from eclipsejavatest import eclipseJavaTest from eclipsejavatest import JavaClass class eclipsePyPrint(eclipseJavaTest): def eclipsepyMain(self): print "python main method" eclipseJavaTest.printerCount(4) print eclipseJavaTest.gotoPython() eclipseJavaTest.printerSentence() samplepyClass = JavaClass("Jython plain") samplepyClass.setName("jython fancy") print samplepyClass.getName() but I'm getting the error ImportError: No module named eclipsejavatest The Python project references the Java project. I've tried exporting the Java project and adding the .jar to the Jython Class Path for the Python project. I'm not sure what to do to get this to work.

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  • On Mac OS X, do you use the shipped python or your own?

    - by The MYYN
    On Tiger, I used a custom python installation to evaluate newer versions and I did not have any problems with that*. Now Snow Leopard is a little more up-to-date and by default ships with $ ls /System/Library/Frameworks/Python.framework/Versions/ 2.3 2.5 2.6 @Current What could be considered best practice? Using the python shipped with Mac OS X or a custom compiled version in, say $HOME. Are there any advantages/disadvantages using the one option over the other? My setup was fairly simple so far and looked like this: Custom compiled Python in $HOME and a $PATH that would look into $HOME/bin first, and subsequently would use my private Python version. Also $PYTHONPATH pointed to this local installation. This way, I did not need to sudo–install packages - virtualenv took care of the rest.

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  • For anyone with free time: Trying to learn how to replace PHP with Python, failing terribly.

    - by MALON
    I want give web development using Python a shot, but I'm failing hard. I don't even know if I CAN run Python. The webpage for my web host says it supports all kinds of stuff, including Python. I've never touched anything CGI related and this does not appear to be a noob friendly area. Below is all the information I could think of that might be useful: Shared host: Yes Webhost: dibbsonhosting.com Server OS: linux Python installed: Yes (or so says the webhost) mod_python installed: Don't Know WSGI installed: Don't Know Access to http.conf: No Terminal access: No Cpanel: Yes FTP: Yes Django: downloaded latest stable release, not uploaded anywhere, not sure where to put it. DB: MySQL 5.x I really want to use Python for web development! Thanks!

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  • Python as your main language. Possible?

    - by Deinumite
    I am currently attending college and the languages that I will 'know' by graduation are C++ and Java. That being said, i am also in the process of teaching myself Python. I know that every programming language has its own pros and cons, but would it be possible to become a python developer out of school? I always have more 'fun' programming in Python than i do in C++ or Java, and I am also in love with Pythons documentation. I know C++ will always be on top in terms of speed, but what would be the benefit of memorizing every javadoc against focusing on Python instead? are there good jobs to be had with Python? edit: also, would it be beneficial for me to look at C# as well? Microsoft is really throwing their support at it so that could be a decent career path as well.

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  • Why is this Python class copying another class contents?

    - by fjfnaranjo
    Hello guys. I'm trying to understand an estrange behavior in Python. I have the next python code: class IntContainer: listOfInts = [] def __init__(self, initListOfInts): for i in initListOfInts: self.listOfInts.append(i) def printInts(self): print self.listOfInts if __name__ == "__main__": intsGroup1 = [1,2,3,4] intsGroup2 = [4,5,6,7] intsGroups = [intsGroup1,intsGroup2] intsContainers = [] for ig in intsGroups: newIntContainer = IntContainer(ig) intsContainers.append(newIntContainer) for ic in intsContainers: print ic.listOfInts I expect to get something like: [1, 2, 3, 4] [4, 5, 6, 7] But i get: [1, 2, 3, 4, 4, 5, 6, 7] [1, 2, 3, 4, 4, 5, 6, 7] I have check the next question: http://stackoverflow.com/questions/1876905/why-is-python-reusing-a-class-instance-inside-in-function And a lot of Python reference, but I can not understand what is happening. I think is related with the newIntContainer identifier reutilization, but I do not understand it deeply. Why Python appears to reused the last reference for the new object, even if I have added it to a permanent list? What can I do to resolve this behavior? Thanks ;)

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  • Unable to install Konstruktor program

    - by George Barnick
    I've recently switched to Linux, having a good knowledge of how it works before switching, since I've had experience working with Ubuntu-based servers for several months. I've been trying to install a LEGO CAD program that I have found based on an open source library. Information on that is here. The program I'm looking at is called Konstruktor, and for the most part it should be working. One dependency however does not seem to be able to install. The missing dependency is "kdelibs5", which I know what it is and what it's for, but can't get it to install. When trying to install, I get this error: george@GEORGE-PC:~$ sudo apt-get install kdelibs5 Reading package lists... Done Building dependency tree Reading state information... Done Package kdelibs5 is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source E: Package 'kdelibs5' has no installation candidate When trying to install the proper package of Konstruktor for my system, I get this error: george@GEORGE-PC:~$ sudo dpkg -i '/home/george/Downloads/konstruktor_0.9-beta1-2_amd64.deb' Selecting previously unselected package konstruktor. (Reading database ... 224684 files and directories currently installed.) Unpacking konstruktor (from .../konstruktor_0.9-beta1-2_amd64.deb) ... dpkg: dependency problems prevent configuration of konstruktor: konstruktor depends on kdelibs5 (>= 4:4.4.5); however: Package kdelibs5 is not installed. dpkg: error processing konstruktor (--install): dependency problems - leaving unconfigured Processing triggers for bamfdaemon ... Rebuilding /usr/share/applications/bamf-2.index... Processing triggers for desktop-file-utils ... Processing triggers for gnome-menus ... Processing triggers for mime-support ... Processing triggers for hicolor-icon-theme ... Processing triggers for shared-mime-info ... Unknown media type in type 'all/all' Unknown media type in type 'all/allfiles' Unknown media type in type 'uri/mms' Unknown media type in type 'uri/mmst' Unknown media type in type 'uri/mmsu' Unknown media type in type 'uri/pnm' Unknown media type in type 'uri/rtspt' Unknown media type in type 'uri/rtspu' Errors were encountered while processing: konstruktor I have tried updating and adding apt repositories for KDE packages, but I continuously get the same error. I tried the package "kdelibs5-dev", which installed fine, but "kdelibs5" won't, and Konstruktor still won't install. I am on Ubuntu 13.10 with GNOME shell on amd64 architecture. Any help would be much appreciated. (originally posted my issue here) Thanks ahead of time.

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  • Cannot install stable Xbox 360 driver

    - by Mohd Arafat Hossain
    When I type in sudo add-apt-repository ppa:grumbel/ppa sudo apt-get update sudo apt-get install xboxdrv then when I go to install the stable driver like this sudo apt-get install xboxdrv-stable I get this mohd-arafat-hossain@TUD:~$ sudo apt-get install xboxdrv-stable [sudo] password for the-ubuntu-documentary: Reading package lists... Done Building dependency tree Reading state information... Done E: Unable to locate package xboxdrv-stable

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  • Ubuntu - Install Mate Desktop - Themes missing?

    - by wegsehen
    I just installed Mate on top of Ubuntu by the following commands: sudo add-apt-repository "deb http://packages.mate-desktop.org/repo/ubuntu oneiric main" sudo apt-get update sudo apt-get install mate-archive-keyring sudo apt-get update sudo apt-get install mate-core sudo apt-get install mate-desktop-environment Which caused no problems, but many things (window theme, Mint menu, ...) are missing. It looks like: But it should look like: How can I install the missing packages?

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  • No C++ option after install Eclipse CDT

    - by Muhammad Khan
    I used terminal to install eclipse with jdk7, and now I want incorporate c/c++ development, so I installed a compiler (gcc 4.7) and and eclipse cdt plugin from the terminal: sudo apt-get install eclipse-cdt But when I restarted eclipse and tried to change the perspective, there was no c++ option I cannot even create a new c++ project. Someone suggested that I do "Install New Software" and choose the cdt from the hard drive. If this is what I should do, where does terminal install its files to?

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  • 12.0.4.1 Reboot before install

    - by Cory
    I'm trying to install 12.04.1 and after I choose install or live, it just goes to a blinking cursor or some text, then reboots the machine. I've tried nomodeset, alternate install, dvd install, and usb. Same problem with all of them. I've also tried unplugging unnecessary devices such as my webcam and 2nd monitor. Specs: gigabyte mobo AMD Phenom II 965 @ 3.7 4gb ddr2 1066 AMD Radeon HD 6870 Creative Sound Blaster X-fi xtreme gamer

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  • Recovering an Ubuntu installation - Ubuntu eats itself after 'sudo apt-get install -f'

    - by Tony Martin
    Updater (I assume) put a no entry style alert icon on the panel which informed me that certain package dependencies were not up to snuff. Upgrades were thereafter only partial. The dialogue advised that I sudo apt-get install -f. I did this hoping that app-get would fulfil dependencies and replace corrupted files and watched it systematically remove every component of linux, both the stuff I had installed and the core ubuntu packages. I could only assume at this stage that this was in preparation for a fresh install but, of course, I know better now - if you find yourself with apt-get warning you that you are about to remove several hundred packages and asking you to type an involved confirmation string seek advice before proceeding. I digress. This was a 64 bit install of 12.04. All that is left is grub pointing to a couple of windows recovery partitions on the hard drive. Thankfully the Ext4 partition is reachable from a stick boot. EDIT: I've logged onto the machine with a 64 bit stick and can see the file structure left behind by apt-get after {ahem} fixing. My first instinct was to run install from the stick but it seemed to want to do another install rather than a repair. My question then: is there a way to recover the current installation so that if I reinstall the packages I had they will pick up the original settings? I'm particularly worried about losing email from evolution - the rest I could probably lash back together. As for the use of PPA I'm not sure what you're driving at. I generally use Ubuntu Software Centre to install software, though I have used terminal scripts to add new repositories and software successfully following guidance on various websites. The most recent change I made was a downgrade of Wine in an attempt to install and run excel2007 (a necessity, I think, as I have VBA work to do). The installer had stalled and had to be killed. I wonder if that corrupted whatever database holds a model of the package installation structure. I would also be interested to know how this disaster came about. I see people in the know recommending the sudo apt-get install -f as a fairly innocuous cure in similar circumstances. Thanks for your attention, Tony Martin p.s. Do please forgive the rant aspects of the original post. It's hard to write rationally with a large hole in the pit of your stomach.

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  • Ubuntu 12.10 install stuck at first step

    - by Josh Clarke
    I'm trying to install Ubuntu 12.10 from a DVD-R disk, and everything is just fine until I get to the first window after clicking "Install Ubuntu" I checked the box "Download updates while installing" and also the "Install third-party software" box. After clicking next, however, the install just hangs there. I've been waiting for over an hour now and all I see is the mouse cursor showing that it's "loading". What should I do to get past this? Thanks!

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  • Install HP driver in ubuntu

    - by dotNET
    Hey, I need to install the wifi driver to ubuntu. so I downloaded the driver from hp website but the extension is .rpm, so I need to convert him to .deb so I can install it on ubuntu. The problem is I don't have internet connection on ubuntu to do this : sudo apt-get install alien how can convert the driver on windows for example, or how can I do download alien and place it under my usb to install it after booting on ubuntu. Thanks

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  • Can't install any Linux distro

    - by rstreeter78
    I have been trying to install Ubuntu on my step-son's netbook and I checked and his hard disk seems to be failing and i keep getting an error message that Ubuntu is unable to install due to hard disk failure. I was wondering how and if it is possible to install Ubuntu on this hard disk without it giving me an error message. I have tried the alternate install disk image and the regular desktop image and get basically the same error message. Is there a way to somehow override this and get it installed

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  • Wubi no longer supports install to fakeraid?

    - by Ryan
    About a week ago I used wubi to install ubuntu onto one of my two raid1 devices in windows 7. I tried to do the same this week on the same mobo/drive combo and now I can't get it to install. It gives me first an "invalid prefix" during the install and then says "completing install" followed by a crash into busybox with a warning that the raid can't be mounted because it already was mounted. Has there been a change in wubi or something in the recent past?

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  • How to install MySQL 5.6?

    - by Ross Smith II
    I just installed Ubuntu 12.10 (amd64), and want to install a recent version of MySQL 5.6. If possible, I would like to install (not upgrade) it the "Debian Way' (i.e., using apt-get or dpkg). The only binaries I could find are here. Unfortunately, they are incomplete, as they only install files in /usr/share. If binaries aren't available, how could I install it from source, using the standard Debian method of installing from source. Thanks for any assistance.

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  • Unable to install applications (Oneiric)

    - by yayu
    When I use the software center to install something, I get the error: An unhandlable error occured There seems to be a programming error in aptdaemon, the software that allows you to install/remove software and to perform other package management related tasks on using the command line: $sudo apt-get install <something> E: dpkg was interrupted, you must manually run 'sudo dpkg --configure -a' to correct the problem. I am unable to install anything. How do we fix this?

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  • uWSGI cannot find "application" using Flask and Virtualenv

    - by skyler
    Using uWSGI to serve a simple wsgi app, (a simple "Hello, World") my configuration works, but when I try to run a Flask app, I get this in uWSGI's error logs: current working directory: /opt/python-env/coefficient/lib/python2.6/site-packages writing pidfile to /var/run/uwsgi.pid detected binary path: /opt/uwsgi/uwsgi setuid() to 497 your memory page size is 4096 bytes detected max file descriptor number: 1024 lock engine: pthread robust mutexes uwsgi socket 0 bound to TCP address 127.0.0.1:3031 fd 3 Python version: 2.6.6 (r266:84292, Jun 18 2012, 14:18:47) [GCC 4.4.6 20110731 (Red Hat 4.4.6-3)] Set PythonHome to /opt/python-env/coefficient/ *** Python threads support is disabled. You can enable it with --enable-threads *** Python main interpreter initialized at 0xbed3b0 your server socket listen backlog is limited to 100 connections *** Operational MODE: single process *** added /opt/python-env/coefficient/lib/python2.6/site-packages/ to pythonpath. unable to find "application" callable in file /var/www/coefficient/flask.py unable to load app 0 (mountpoint='') (callable not found or import error) *** no app loaded. going in full dynamic mode *** *** uWSGI is running in multiple interpreter mode ***` Note in particular this part of the log: unable to find "application" callable in file /var/www/coefficient/flask.py unable to load app 0 (mountpoint='') (callable not found or import error) **no app loaded. going in full dynamic mode** This is my Flask app: from flask import Flask app = Flask(__name__) @app.route("/") def hello(): return "Hello, World, from Flask!" Before I added my Virtualenv's pythonpath to my configuration file, I was getting an ImportError for Flask. I solved this though, I believe (I'm not receiving errors about it anymore) and here is my complete configuration file: uwsgi: #socket: /tmp/uwsgi.sock socket: 127.0.0.1:3031 daemonize: /var/log/uwsgi.log pidfile: /var/run/uwsgi.pid master: true vacuum: true #wsgi-file: /var/www/coefficient/coefficient.py wsgi-file: /var/www/coefficient/flask.py processes: 1 virtualenv: /opt/python-env/coefficient/ pythonpath: /opt/python-env/coefficient/lib/python2.6/site-packages This is how I start uWSGI, from an rc script: /opt/uwsgi/uwsgi --yaml /etc/uwsgi/conf.yaml --uid uwsgi And if I try to view the Flask program in a browser, I get this: **uWSGI Error** Python application not found Any help is appreciated.

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  • MySQLdb within python2.5 virtualenv

    - by wizard
    I have a Fedora 11 box with MySQL server. Fedora 11 uses python 2.6 internally and python 2.6 is automatically installed on the box. I have created a python virtual-env for version 2.5.5, so that I can run turbogears 1.x application. I have MySQLdb rpm installed on the box (and it works fine with python 2.6). When I import MySQLdb from within python version 2.6 it imports is successfully. When I import MySQLdb from within the python 2.5.5 virtual-env the import fails (because I have installed virtual-env with --no-site-packages). So, I have to install MySQLdb python as a local package (local to virtual-env). 'easy_install MySQL-python' within the virtual env fails. It downloads the MySQL-python-1.2.3.c1.tar.gz/download, but the 'python setup.py build' fails with error. The same problem occurs when building the MySQL outside of virtual-env. Is the 'python setup.py build' for MySQL-python trying to link to a library (and am I missing some library)? Or is the downloaded code missing some header files (unlikely)? Thanks.

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  • Installing PIL on Cygwin

    - by Dustin
    I've been struggling all morning to get PIL installed on Cygwin. The errors I get are not consistent with common errors I find using Google. Perhaps a linux guru can see an obvious problem in this output: $ python setup.py install running install running build running build_py running build_ext building '_imaging' extension gcc -fno-strict-aliasing -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes -DHAVE_LIBZ -I/usr/include/freetype2 -IlibImaging -I/usr/include -I/usr/include/python2.5 -c _imaging.c -o build/temp.cygwin-1.7.2-i686-2.5/_imaging.o In file included from /usr/lib/gcc/i686-pc-cygwin/3.4.4/include/syslimits.h:7, from /usr/lib/gcc/i686-pc-cygwin/3.4.4/include/limits.h:11, from /usr/include/python2.5/Python.h:18, from _imaging.c:75: /usr/lib/gcc/i686-pc-cygwin/3.4.4/include/limits.h:122:61: limits.h: No such file or directory In file included from _imaging.c:75: /usr/include/python2.5/Python.h:32:19: stdio.h: No such file or directory /usr/include/python2.5/Python.h:34:5: #error "Python.h requires that stdio.h define NULL." /usr/include/python2.5/Python.h:37:20: string.h: No such file or directory /usr/include/python2.5/Python.h:39:19: errno.h: No such file or directory /usr/include/python2.5/Python.h:41:20: stdlib.h: No such file or directory /usr/include/python2.5/Python.h:43:20: unistd.h: No such file or directory /usr/include/python2.5/Python.h:55:20: assert.h: No such file or directory In file included from /usr/include/python2.5/Python.h:57, from _imaging.c:75: /usr/include/python2.5/pyport.h:7:20: stdint.h: No such file or directory In file included from /usr/include/python2.5/Python.h:57, from _imaging.c:75: /usr/include/python2.5/pyport.h:89: error: parse error before "Py_uintptr_t" /usr/include/python2.5/pyport.h:89: warning: type defaults to `int' in declaration of `Py_uintptr_t' /usr/include/python2.5/pyport.h:89: warning: data definition has no type or storage class /usr/include/python2.5/pyport.h:90: error: parse error before "Py_intptr_t" /usr/include/python2.5/pyport.h:90: warning: type defaults to `int' in declaration of `Py_intptr_t' ... more lines like this

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  • How to have PHP and mod_wsgi python app on the same domain?

    - by Lazik
    I am using apache with mod_wsgi (python3) on ubuntu 12.04. I have a python app (bottle) which is at www.mysite.com/ In my python app I have routes like www.mysite.com/abbb?q=blab I would like a path www.mysite.com/forum to resolve to a php app (simple machine forums) Ideally I would like to use apache to handle the forum part and pass it to php (instead of coding it in the python app). Don't know if it's possible. I'm new to this, I have read https://code.google.com/p/modwsgi/wiki/ConfigurationGuidelines#The_Apache_Alias_Directive but I don't understand how to use it. Here is my apache conf for the mod_wsgi app, I don't know how to specify the PHP portion. <VirtualHost *:80> ServerName www.ex.com ServerAlias ex.com *.ex.com RewriteEngine On RewriteCond %{HTTP_HOST} !^www\. RewriteRule ^(.*)$ http://www.%{HTTP_HOST}$1 [R=301,L] WSGIDaemonProcess ex user=www-data group=www-data processes=1 threads=5 WSGIScriptAlias / /var/www/vhosts/ex/app.wsgi <Directory /var/www/vhosts/ex> WSGIProcessGroup ex WSGIApplicationGroup %{GLOBAL} Order deny,allow Allow from all </Directory> </VirtualHost>

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  • puppet execution of a python script where os.system(...) command is not working

    - by philippe
    I am trying to manage Unix users with puppet. Puppet provides enough tools to create accounts and provide authorized_keys files for instance, but no to set up user password, and it tell to the user. What I have done is a python script which generate a random password and send it to the user by email. The problem is, it is not possible to launch passwd Unix command with python, I have then written a bash script with the command: echo -ne "$password\n$password\n" | passwd $user passwd -e $user Launched manually, the script works fine and the created user has its password sent by email. But when puppet launches it, only the python script gets executed, as if the os.system('/bin/bash my_bash_script') is ignored. No error is displayed. And the user gets its password, but the passwd commands are not launched. Is there any limitation with puppet preventing to perform what I described? Or, how can I otherwise change the user account, its expiration, and send password by email? I can provide more information, but right now, I don't know which are accurate. Many thanks!

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  • How to combine twill and python into one code that could be run on "Google App Engine"?

    - by brilliant
    Hello everybody!!! I have installed twill on my computer (having previously installed Python 2.5) and have been using it recently. Python is installed on disk C on my computer: C:\Python25 And the twill folder (“twill-0.9”) is located here: E:\tmp\twill-0.9 Here is a code that I’ve been using in twill: go “some website’s sign-in page URL” formvalue 2 userid “my login” formvalue 2 pass “my password” submit go “URL of some other page from that website” save_html result.txt This code helps me to log in to one website, in which I have an account, record the HTML code of some other page of that website (that I can access only after logging in), and store it in a file named “result.txt” (of course, before using this code I firstly need to replace “my login” with my real login, “my password” with my real password, “some website’s sign-in page URL” and “URL of some other page from that website” with real URLs of that website, and number 2 with the number of the form on that website that is used as a sign-in form on that website’s log-in page) This code I store in “test.twill” file that is located in my “twill-0.9” folder: E:\tmp\twill-0.9\test.twill I run this file from my command prompt: python twill-sh test.twill Now, I also have installed “Google App Engine SDK” from “Google App Engine” and have also been using it for awhile. For example, I’ve been using this code: import hashlib m = hashlib.md5() m.update("Nobody inspects") m.update(" the spammish repetition ") print m.hexdigest() This code helps me transform the phrase “Nobody inspects the spammish repetition” into md5 digest. Now, how can I put these two pieces of code together into one python script that I could run on “Google App Engine”? Let’s say, I want my code to log in to a website from “Google App Engine”, go to another page on that website, record its HTML code (that’s what my twill code does) and than transform this HTML code into its md5 digest (that’s what my second code does). So, how can I combine those two codes into one python code? I guess, it should be done somehow by importing twill, but how can it be done? Can a python code - the one that is being run by “Google App Engine” - import twill from somewhere on the internet? Or, perhaps, twill is already installed on “Google App Engine”?

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  • How can I build the Boost.Python example on Ubuntu 9.10?

    - by Gatlin
    I am using Ubuntu 9.10 beta, whose repositories contain boost 1.38. I would like to build the hello-world example. I followed the instructions here (http://www.boost.org/doc/libs/1%5F40%5F0/libs/python/doc/tutorial/doc/html/python/hello.html), found the example project, and issued the "bjam" command. I have installed bjam and boost-build. I get the following output: Jamroot:18: in modules.load rule python-extension unknown in module Jamfile</usr/share/doc/libboost1.38-doc/examples/libs/python/example>. /usr/share/boost-build/build/project.jam:312: in load-jamfile /usr/share/boost-build/build/project.jam:68: in load /usr/share/boost-build/build/project.jam:170: in project.find /usr/share/boost-build/build-system.jam:248: in load /usr/share/boost-build/kernel/modules.jam:261: in import /usr/share/boost-build/kernel/bootstrap.jam:132: in boost-build /usr/share/doc/libboost1.38-doc/examples/libs/python/example/boost-build.jam:7: in module scope I do not know enough about Boost (this is an exploratory exercise for myself) to understand why the python-extension macro in the included Jamroot is not valid. I am running this example from the install directory, so I have not altered the Jamroot's use-project setting. As a side question, if I were to just willy-nilly start a project in an arbitrary directory, how would I write my jamroot?

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  • Optimization in Python - do's, don'ts and rules of thumb.

    - by JV
    Well I was reading this post and then I came across a code which was: jokes=range(1000000) domain=[(0,(len(jokes)*2)-i-1) for i in range(0,len(jokes)*2)] I thought wouldn't it be better to calculate the value of len(jokes) once outside the list comprehension? Well I tried it and timed three codes jv@Pioneer:~$ python -m timeit -s 'jokes=range(1000000);domain=[(0,(len(jokes)*2)-i-1) for i in range(0,len(jokes)*2)]' 10000000 loops, best of 3: 0.0352 usec per loop jv@Pioneer:~$ python -m timeit -s 'jokes=range(1000000);l=len(jokes);domain=[(0,(l*2)-i-1) for i in range(0,l*2)]' 10000000 loops, best of 3: 0.0343 usec per loop jv@Pioneer:~$ python -m timeit -s 'jokes=range(1000000);l=len(jokes)*2;domain=[(0,l-i-1) for i in range(0,l)]' 10000000 loops, best of 3: 0.0333 usec per loop Observing the marginal difference 2.55% between the first and the second made me think - is the first list comprehension domain=[(0,(len(jokes)*2)-i-1) for i in range(0,len(jokes)*2)] optimized internally by python? or is 2.55% a big enough optimization (given that the len(jokes)=1000000)? If this is - What are the other implicit/internal optimizations in Python ? What are the developer's rules of thumb for optimization in Python? Edit1: Since most of the answers are "don't optimize, do it later if its slow" and I got some tips and links from Triptych and Ali A for the do's. I will change the question a bit and request for don'ts. Can we have some experiences from people who faced the 'slowness', what was the problem and how it was corrected? Edit2: For those who haven't here is an interesting read Edit3: Incorrect usage of timeit in question please see dF's answer for correct usage and hence timings for the three codes.

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