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  • Python version issues

    - by MidnightLightning
    I have a Mac which uses MacPorts to have multiple versions of Python installed and use the python_select application to switch between them. Currently, this Mac has OS 10.6.6, which comes with Python 2.6.1 installed as /usr/bin/python. Using MacPorts, I've installed the python27, python31, and python_select ports and now have this issue: python_select seems to not be switching the default python properly: $ which python /usr/bin/python $ python -V Python 2.6.1 $ /usr/bin/python -V Python 2.6.1 $ sudo python_select python27 Selecting version "python27" for python $ which python /opt/local/bin/python $ ls -l /opt/local/bin/python lrwxr-xr-x 1 root admin 24B Mar 18 10:24 /opt/local/bin/python -> /opt/local/bin/python2.7 $ python -V Python 2.6.1 # <-- Wrong!!! $ /opt/local/bin/python -V Python 2.7.1 # <-- Why are you not default? So, after running python_select, which python seems to think that the /opt/local/bin version is going to be used, but in reality, it seems that the /usr/bin one is taking precedent unless I specifically call the /opt/local/bin one. Is there something I'm doing wrong?

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  • How can I get sikuli-ide to work?

    - by ayckoster
    I installed sikuli-ide with sudo apt-get install sikuli-ide Everything was fine until I tried to start it from the terminal. I typed sikuli-ide But the only response I got was [info] locale: en_US The application was not started, furthermore there is no desktop file and sikuli-ide does not show up in Dash Home. I guess there is something wrong with the package. I run Ubuntu 12.10 64bit. I tried to install it (Sikuli-X-1.0rc3 (r905)-linux-x86_64.zip) from their page, now the IDE starts, but when I try to execute a simple script I get the following error: [error] Stopped [error] An error occurs at line 1 [error] Error message: Traceback (most recent call last): File "", line 1, in File "/home/ayckoster/opt/Sikuli-IDE/sikuli-script.jar/Lib/sikuli/__init__.py", line 3, in File "/home/ayckoster/opt/Sikuli-IDE/sikuli-script.jar/Lib/sikuli/Sikuli.py", line 22, in java.lang.UnsatisfiedLinkError: /home/ayckoster/opt/Sikuli-IDE/libs/libVisionProxy.so: libml.so.2.1: cannot open shared object file: No such file or directory at java.lang.ClassLoader$NativeLibrary.load(Native Method) at java.lang.ClassLoader.loadLibrary1(ClassLoader.java:1935) at java.lang.ClassLoader.loadLibrary0(ClassLoader.java:1860) at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1821) at java.lang.Runtime.load0(Runtime.java:792) at java.lang.System.load(System.java:1059) at com.wapmx.nativeutils.jniloader.NativeLoader.loadLibrary(NativeLoader.java:44) at org.sikuli.script.Finder.(Finder.java:33) at java.lang.Class.forName0(Native Method) at java.lang. Class.forName(Class.java:264) at org.python.core.Py.loadAndInitClass(Py.java:895) at org.python.core.Py.findClassInternal(Py.java:830) at org.python.core.Py.findClassEx(Py.java:881) at org.python.core.packagecache.SysPackageManager.findClass(SysPackageManager.java:133) at org.python.core.packagecache.PackageManager.findClass(PackageManager.java:28) at org.python.core.packagecache.SysPackageManager.findClass(SysPackageManager.java:122) at org.python.core.PyJavaPackage.__findattr_ex__(PyJavaPackage.java:137) at org.python.core.PyObject.__findattr__(PyObject.java:863) at org.python.core.imp.import_name(imp.java:849) at org.python.core.imp.importName(imp.java:884) at org.python.core.ImportFunction.__call__(__builtin__.java:1220) at org.python.core.PyObject.__call__(PyObject.java:357) at org.python.core.__builtin__.__import__(__builtin__.java:1173) at org.python.core.imp.importFromAs(imp.java:978) at org.python.core.imp.importFrom(imp.java:954) at sikuli.Sikuli$py.f$0(/home/ayckoster/opt/Sikuli-IDE/siku li-script.jar/Lib/sikuli/Sikuli.py:211) at sikuli.Sikuli$py.call_function(/home/ayckoster/opt/Sikuli-IDE/sikuli-script.jar/Lib/sikuli/Sikuli.py) at org.python.core.PyTableCode.call(PyTableCode.java:165) at org.python.core.PyCode.call(PyCode.java:18) at org.python.core.imp.createFromCode(imp.java:386) at org.python.core.util.importer.importer_load_module(importer.java:109) at org.python.modules.zipimport.zipimporter.zipimporter_load_module(zipimporter.java:161) at org.python.modules.zipimport.zipimporter$zipimporter_load_module_exposer.__call__(Unknown Source) at org.python.core.PyBuiltinMethodNarrow.__call__(PyBuiltinMethodNarrow.java:47) at org.python.core.imp.loadFromLoader(imp.java:513) at org.python.core.imp.find_module(imp.java:467) at org.python.core.PyModule.impAttr(PyModule.java:100) at org.python.core.imp.import_next(imp.java:715) at org.python.core.imp.import_name(imp.java:824) at org.python.core.imp.importName(imp.java:884) at org.python.core.ImportFunction.__call__(__builtin__.java:1220) at org.python.core.PyObject.__call__(PyObject.java:357) at org.python.core.__builtin__.__import__(__builtin__.java:1173) at org.python.core.imp.importAll(imp.java:998) at sikuli$py.f$0(/home/ayckoster/opt/Sikuli-IDE/sikuli-script.jar/Lib/sikuli/__init__.py:3) at sikuli$py.call_function(/home/ayckoster/opt/Sikuli-IDE/sikuli-script.jar/Lib/sikuli/__init__.py) at org.python.core.PyTableCode.call(PyTableCode.java:165) at org.python.core.PyCode.call(PyCode.java:18) at org.python.core.imp.createFromCode(imp.java:386) at org.python.core.util.importer.importer_load_module(importer.java:109) at org.python.modules.zipimport.zipimporter.zipimporter_load_module(zipimporter.java:161) at org.python.modules.zipimport.zipimporter$zipimporter_load_module_exposer.__call__(Unknown Source) at org.python.core.PyBuiltinMethodNarrow.__call__(PyBuiltinMethodNarrow.java:47) at org.python.core.imp.loadFromLoader(imp.java:513) at org.python.core.imp.find_module(imp.java:467) at org.python.core.imp.import_next(imp.java:713) at or g.python.core.imp.import_name(imp.java:824) at org.python.core.imp.importName(imp.java:884) at org.python.core.ImportFunction.__call__(__builtin__.java:1220) at org.python.core.PyObject.__call__(PyObject.java:357) at org.python.core.__builtin__.__import__(__builtin__.java:1173) at org.python.core.imp.importAll(imp.java:998) at org.python.pycode._pyx2.f$0(:1) at org.python.pycode._pyx2.call_function() at org.python.core.PyTableCode.call(PyTableCode.java:165) at org.python.core.PyCode.call(PyCode.java:18) at org.python.core.Py.runCode(Py.java:1261) at org.python.core.Py.exec(Py.java:1305) at org.python.util.PythonInterpreter.exec(PythonInterpreter.java:206) at org.sikuli.script.ScriptRunner.runPython(ScriptRunner.java:61) at org.sikuli.ide.SikuliIDE$ButtonRun.runPython(SikuliIDE.java:1572) at org.sikuli.ide.SikuliIDE$ButtonRun$1.run(SikuliIDE.java:1677) java.lang.UnsatisfiedLinkError: java.lang.UnsatisfiedLinkError: /home/ayckoster/opt/Sikuli-IDE/libs/libVisionProxy.so: libml.so.2.1: cannot open shared object file: No such file or directory If I try to use the click() method from the gui it fails. So I created my own click method and it look like this: This cannot be executed and produces the error above.

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  • Build problems when adding `__str__` method to Boost Python C++ class

    - by Rickard
    I have started to play around with boost python a bit and ran into a problem. I tried to expose a C++ class to python which posed no problems. But I can't seem to manage to implement the __str__ functionality for the class without getting build errors I don't understand. I'm using boost 1_42 prebuild by boostpro. I build the library using cmake and the vs2010 compiler. I have a very simple setup. The header-file (tutorial.h) looks like the following: #include <iostream> namespace TestBoostPython{ class TestClass { private: double m_x; public: TestClass(double x); double Get_x() const; void Set_x(double x); }; std::ostream &operator<<(std::ostream &ostr, const TestClass &ts); }; and the corresponding cpp-file looks like: #include <boost/python.hpp> #include "tutorial.h" using namespace TestBoostPython; TestClass::TestClass(double x) { m_x = x; } double TestClass::Get_x() const { return m_x; } void TestClass::Set_x(double x) { m_x = x; } std::ostream &operator<<(std::ostream &ostr, TestClass &ts) { ostr << ts.Get_x() << "\n"; return ostr; } BOOST_PYTHON_MODULE(testme) { using namespace boost::python; class_<TestClass>("TestClass", init<double>()) .add_property("x", &TestClass::Get_x, &TestClass::Set_x) .def(str(self)) ; } The CMakeLists.txt looks like the following: CMAKE_MINIMUM_REQUIRED(VERSION 2.8) project (testme) FIND_PACKAGE( Boost REQUIRED ) FIND_PACKAGE( Boost COMPONENTS python REQUIRED ) FIND_PACKAGE( PythonLibs REQUIRED ) set(Boost_USE_STATIC_LIBS OFF) set(Boost_USE_MULTITHREAD ON) INCLUDE_DIRECTORIES(${Boost_INCLUDE_DIRS}) INCLUDE_DIRECTORIES ( ${PYTHON_INCLUDE_PATH} ) add_library(testme SHARED tutorial.cpp) target_link_libraries(testme ${Boost_PYTHON_LIBRARY}) target_link_libraries(testme ${PYTHON_LIBRARY} The build error I get is the following: Compiling... tutorial.cpp C:\Program Files (x86)\boost\boost_1_42\boost/python/def_visitor.hpp(31) : error C2780: 'void boost::python::api::object_operators::visit(ClassT &,const char *,const boost::python::detail::def_helper &) const' : expects 3 arguments - 1 provided with [ U=boost::python::api::object ] C:\Program Files (x86)\boost\boost_1_42\boost/python/object_core.hpp(203) : see declaration of 'boost::python::api::object_operators::visit' with [ U=boost::python::api::object ] C:\Program Files (x86)\boost\boost_1_42\boost/python/def_visitor.hpp(67) : see reference to function template instantiation 'void boost::python::def_visitor_access::visit,classT>(const V &,classT &)' being compiled with [ DerivedVisitor=boost::python::api::object, classT=boost::python::class_, V=boost::python::def_visitor ] C:\Program Files (x86)\boost\boost_1_42\boost/python/class.hpp(225) : see reference to function template instantiation 'void boost::python::def_visitor::visit>(classT &) const' being compiled with [ DerivedVisitor=boost::python::api::object, W=TestBoostPython::TestClass, classT=boost::python::class_ ] .\tutorial.cpp(29) : see reference to function template instantiation 'boost::python::class_ &boost::python::class_::def(const boost::python::def_visitor &)' being compiled with [ W=TestBoostPython::TestClass, U=boost::python::api::object, DerivedVisitor=boost::python::api::object ] Does anyone have any idea on what went wrrong? If I remove the .def(str(self)) part from the wrapper code, everything compiles fine and the class is usable from python. I'd be very greatful for assistance. Thank you, Rickard

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  • How to organize Python modules for PyPI to support 2.x and 3.x

    - by Craig McQueen
    I have a Python module that I would like to upload to PyPI. So far, it is working for Python 2.x. It shouldn't be too hard to write a version for 3.x now. But, after following guidelines for making modules in these places: Distributing Python Modules The Hitchhiker’s Guide to Packaging it's not clear to me how to support multiple source distributions for different versions of Python, and it's not clear if/how PyPI could support it. I envisage I would have separate code for: 2.x 2.6 (maybe, as a special case to use the new buffer API) 3.x How is it possible to set up a Python module in PyPI so that someone can do: easy_install modulename and it will install the right thing whether the user is using 2.x or 3.x?

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  • How to organize Python modules for PyPI to support 2.x and 3.x

    - by Craig McQueen
    I have a Python module that I would like to upload to PyPI. So far, it is working for Python 2.x. It shouldn't be too hard to write a version for 3.x now. But, after following guidelines for making modules in these places: Distributing Python Modules The Hitchhiker’s Guide to Packaging it's not clear to me how to support multiple source distributions for different versions of Python, and it's not clear if/how PyPI could support it. I envisage I would have separate code for: 2.x 2.6 (maybe, as a special case to use the new buffer API) 3.x How is it possible to set up a Python module in PyPI so that someone can do: easy_install modulename and it will install the right thing whether the user is using 2.x or 3.x?

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  • Prevent Python from caching the imported modules

    - by Olivier
    While developing a largeish project (split in several files and folders) in Python with IPython, I run into the trouble of cached imported modules. The problem is that instructions import module only reads the module once, even if that module has changed! So each time I change something in my package, I have to quit and restart IPython. Painful. Is there any way to properly force reloading some modules? Or, better, to somehow prevent Python from caching them? I tried several approaches, but none works. In particular I run into really, really weird bugs, like some modules or variables mysteriously becoming equal to None... The only sensible resource I found is Reloading Python modules, from pyunit, but I have not checked it. I would like something like that. A good alternative would be for IPython to restart, or restart the Python interpreter somehow. So, if you develop in Python, what solution have you found to this problem?

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  • Using Crypt function Python 3.3.2

    - by adampski
    In Windows and Python version 3.3.2, I try and call the python module like so: hash2 = crypt(word, salt) I import it at the top of my program like so: from crypt import * The result I get is the following: Traceback (most recent call last): File "C:\none\of\your\business\adams.py", line 10, in <module> from crypt import * File "C:\Python33\lib\crypt.py", line 3, in <module> import _crypt ImportError: No module named '_crypt' However, when I execute the same file adams.py in Ubuntu, with Python 2.7.3, it executes perfectly - no errors. I tried the following to resolve the issue for my Windows & Python 3.3.2 (though I'm sure the OS isn't the issue, the Python version or my use of syntax is the issue): Rename the directory in the Python33 directory from Lib to lib Rename the crypt.py in lib to _crypt.py. However, it turns out the entire crypt.py module depends on an external module called _crypt.py too. Browsed internet to download anything remotely appropriate to resemble _crypt.py It's not Python, right? It's me...(?) I'm using syntaxes to import and use external modules that are acceptable in 2.7.3, but not in 3.3.2. Or have I found a bug in 3.3.2?

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  • Python 2 dict_items.sort() in Python 3

    - by DaveWeber
    I'm porting some code from Python 2 to 3. This is valid code in Python 2 syntax: def print_sorted_dictionary(dictionary): items=dictionary.items() items.sort() In Python 3, the dict_items have no method 'sort' - how can I make a workaround for this in Python 3?

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  • Making python 3.3 default python 3 interpreter instead of 3.2

    - by user1873947
    So, to keep it simple. Ubuntu 12.10 has python 3.2 pre installed and it is linked to "python3". I downloaded python 3.3 and it's command is "python3.3". However, I downloaded pySide for python3 from synaptic. Using "from PySide.QtCore import *" fails on python3.3. BUT, when I ran just "python3" (aka 3.2) everything works fine. Synaptic just installed lib for python3.2 which is default for python3 in ubuntu. How can I force synaptic to install modules for python3.3? Thanks

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  • Best practise for Progress Bar in Python's PyGTK

    - by Matthew Walker
    I would like to get feedback on others' opinions of best practice for how to implement a progress bar in Python's PyGTK. The work that the progress bar was to represent was very significant computationally. Therefore, I wanted the work to be done in a separate process (thus giving the operating system the possibility to run it on a different core). I wanted to be able to start the work, and then continue to use the GUI for other tasks while waiting for the results. I have seen many people asking this question indirectly, but I have not seen any concrete expert advice. I hope that by asking this question we will see a community's combined expertise. I have read the FAQ and I hope that "Programmers" is the right place to ask.

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  • sudo apt-get install python.pip python-dev Gives Error

    - by user2539745
    I am learning Django from http://gettingstartedwithdjango.com/ and I have windows 7 32-bit. The tutorial asked to install virtualbox and vagrant(tutorial had precise64 and it had issues in my pc so I installed precise32) so I did it. Now the tutorial asked to do sudo apt-get install python-dev python.pip so I did it but it gave me this error > vagrant@precise32:~$ sudo apt-get install python.pip python-dev Reading package lists... Done Building dependency tree Reading state information... Done Note, selecting 'python-pip' for regex 'python.pip' Note, selecting 'python-pipeline' for regex 'python.pip' The following extra packages will be installed: libexpat1 libexpat1-dev libpython2.7 python-pkg-resources python-setuptools python-support python2.7 python2.7-dev python2.7-minimal Suggested packages: python-distribute python-distribute-doc python2.7-doc binfmt-support The following NEW packages will be installed: libexpat1-dev libpython2.7 python-dev python-pip python-pipeline python-pkg-resources python-setuptools python-support python2.7-dev The following packages will be upgraded: libexpat1 python2.7 python2.7-minimal 3 upgraded, 9 newly installed, 0 to remove and 63 not upgraded. Need to get 34.7 MB/35.7 MB of archives. After this operation, 42.0 MB of additional disk space will be used. Do you want to continue [Y/n]? y Err (http removed)us.archive.ubuntu.com/ubuntu/ precise-updates/main python2.7 i386 2.7 .3-0ubuntu3.1 404 Not Found [IP: 91.189.91.15 80] Err (http removed)us.archive.ubuntu.com/ubuntu/ precise-updates/main python2.7-minimal i386 2.7.3-0ubuntu3.1 404 Not Found [IP: 91.189.91.15 80] Err (http removed)us.archive.ubuntu.com/ubuntu/ precise-updates/main libpython2.7 i386 2.7.3-0ubuntu3.1 404 Not Found [IP: 91.189.91.15 80] Err (http removed)us.archive.ubuntu.com/ubuntu/ precise-updates/main python2.7-dev i386 2.7.3-0ubuntu3.1 404 Not Found [IP: 91.189.91.15 80] Failed to fetch (http removed)us.archive.ubuntu.com/ubuntu/pool/main/p/python2.7/python 2.7_2.7.3-0ubuntu3.1_i386.deb 404 Not Found [IP: 91.189.91.15 80] Failed to fetch (http removed)us.archive.ubuntu.com/ubuntu/pool/main/p/python2.7/python 2.7-minimal_2.7.3-0ubuntu3.1_i386.deb 404 Not Found [IP: 91.189.91.15 80] Failed to fetch (http removed)us.archive.ubuntu.com/ubuntu/pool/main/p/python2.7/libpyt hon2.7_2.7.3-0ubuntu3.1_i386.deb 404 Not Found [IP: 91.189.91.15 80] Failed to fetch (http removed)us.archive.ubuntu.com/ubuntu/pool/main/p/python2.7/python 2.7-dev_2.7.3-0ubuntu3.1_i386.deb 404 Not Found [IP: 91.189.91.15 80] E: Unable to fetch some archives, maybe run apt-get update or try with --fix-mis sing? Please help what should I do ??

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  • Python IDLE: How to type correct indentation?

    - by user2988464
    Mac: Maverick Python: 3.4 I tried to testtimeit module in Python's IDLE import timeit >>> timeit.timeit( "obj.method", """ class SomeClass: def method(self): pass obj = SomeClass() """) When I tried to type def method(self): on the next line of class SomeClass, I hit Tab, it prompted a window showing the files inside my Document directory. So I hit Ctrl+Tab instead. But I still got the error: Traceback (most recent call last): File "<pyshell#26>", line 6, in <module> """) File "/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/timeit.py", line 213, in timeit return Timer(stmt, setup, timer).timeit(number) File "/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/timeit.py", line 122, in __init__ code = compile(src, dummy_src_name, "exec") File "<timeit-src>", line 9 _t0 = _timer() ^ IndentationError: unindent does not match any outer indentation level Can someone explain: how to fix it, and how to avoid the prompt of My Document appear? Thx!!!

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  • How to install python modules for specific python version

    - by Zayatzz
    I needed to install UCS2 python next to UCS4 python. So I went to comp.lang.python and asked them about it. Probably not the best place to ask it, but they answered https://groups.google.com/forum/?fromgroups#!topic/comp.lang.python/bGuAfqa76W8 and now i have brand new python 2.7.3 ucs2 installed in /opt/bin/python What I need now is - how can I install all other python modules that I have installed for that python version also. Basically stuff like PIL and postgresql and mod_wsgi - basically everything needed to run Django for that python version. Is this the right the place to ask for it?

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  • call python with system() in R to run a python script emulating the python console

    - by Yihui
    I want to pass a chunk of Python code to Python in R with something like system('python ...'), and I'm wondering if there is an easy way to emulate the python console in this case. For example, suppose the code is "print 'hello world'", how can I get the output like this in R? >>> print 'hello world' hello world This only shows the output: > system("python -c 'print \"hello world\"'") hello world Thanks! BTW, I asked in r-help but have not got a response yet (if I do, I'll post the answer here).

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  • Command-Query-Separation and multithreading safe interfaces

    - by Tobias Langner
    I like the command query separation pattern (from OOSC / Eiffel - basically you either return a value or you change the state of the class - but not both). This makes reasoning about the class easier and it is easier to write exception safe classes. Now, with multi threading, I run into a major problem: the separation of the query and the command basically invalidates the result from the query as anything can happen between those 2. So my question is: how do you handle command query separation in an multi-threaded environment? Clarification example: A stack with command query separation would have the following methods: push (command) pop (command - but does not return a value) top (query - returns the value) empty (query) The problem here is - I can get empty as status, but then I can not rely on top really retrieving an element since between the call of empty and the call of top, the stack might have been emptied. Same goes for pop & top. If I get an item using top, I can not be sure that the item that I pop is the same. This can be solved using external locks - but that's not exactly what I call threadsafe design.

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  • Number crunching algo for learning multithreading?

    - by Austin Henley
    I have never really implemented anything dealing with threads; my only experience with them is reading about them in my undergrad. So I want to change that by writing a program that does some number crunching, but splits it up into several threads. My first ideas for this hopefully simple multithreaded program were: Beal's Conjecture brute force based on my SO question. Bailey-Borwein-Plouffe formula for calculating Pi. Prime number brute force search As you can see I have an interest in math and thought it would be fun to incorporate it into this, rather than coding something such as a server which wouldn't be nearly as fun! But the 3 ideas don't seem very appealing and I have already done some work on them in the past so I was curious if anyone had any ideas in the same spirit as these 3 that I could implement?

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  • Multithreading: Communication from Parent thread to child thread

    - by Dennis Nowland
    I have a List of threads normally 3 threads each of the threads reference a webbrowser control that communicates with the parent control to populate a datagridview. What I need to do is when the user clicks the button in a datagridviewButtonCell corresponding data will be sent back to the webbrowser control within the child thread that originally communicated with the main thread. but when I try to do this I receive the following error message 'COM object that has been separated from its underlying RCW cannot be used.' my problem is that I can not figure out how to reference the relevant webbrowser control. I would appreciate any help that anyone can give me. The language used is c# winforms .Net 4.0 targeted Code sample: The following code is executed when user click on the Start button in the main thread private void StartSubmit(object idx) { /* method used by the new thread to initialise a 'myBrowser' inherited from the webbrowser control each submitters object is an a custom Control called 'myBrowser' which holds detail about the function of the object eg: */ //index: is an integer value which represents the threads id int index = (int)idx; //submitters[index] is an instance of the 'myBrowser' control submitters[index] = new myBrowser(); //threads integer id submitters[index]._ThreadNum = index; // naming convention used 'browser' +the thread index submitters[index].Name = "browser" + index; //set list in 'myBrowser' class to hold a copy of the list found in the main thread submitters[index]._dirs = dirLists[index]; // suppress and javascript errors the may occur in the 'myBrowser' control submitters[index].ScriptErrorsSuppressed = true; //execute eventHandler submitters[index].DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(DocumentCompleted); //advance to the next un-opened address in datagridview the navigate the that address //in the 'myBrowser' control. SetNextDir(submitters[index]); } private void btnStart_Click(object sender, EventArgs e) { // used to fill list<string> for use in each thread. fillDirs(); //connections is the list<Thread> holding the thread that have been opened //1 to 10 maximum for (int n = 0; n < (connections.Length); n++) { //initialise new thread to the StartSubmit method passing parameters connections[n] = new Thread(new ParameterizedThreadStart(StartSubmit)); // naming convention used conn + the threadIndex ie: 'conn1' to 'conn10' connections[n].Name = "conn" + n.ToString(); // due to the webbrowser control needing to be ran in the single //apartment state connections[n].SetApartmentState(ApartmentState.STA); //start thread passing the threadIndex connections[n].Start(n); } } Once the 'myBrowser' control is fully loaded I am inserting form data into webforms found in webpages loaded via data enter into rows found in the datagridview. Once a user has entered the relevant details into the different areas in the row the can then clicking a DataGridViewButtonCell that has tha collects the data entered and then has to be send back to the corresponding 'myBrowser' object that is found on a child thread. Thank you

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  • Requiring multithreading/concurrency for implementation of scripting language

    - by Ricky Stewart
    Here's the deal: I'm looking at designing my own scripting/interpreted language for fun. I'm only in the planning stages right now; I want to make sure I have a very strong hold on exactly how I will implement everything before I start coding. What I'm currently struggling with is concurrency. It seems to me like an easy way to avoid the unpredictable performance that comes with garbage collection would be to put the garbage collector in its own thread, and have it run concurrently with the interpreter itself. (To be clear, I don't plan to allow the scripts to be multithreaded themselves; I would simply put a garbage collector to work in a different thread than the interpreter.) This doesn't seem to be a common strategy for many popular scripting languages, probably for portability reasons; I would probably write the interpreter in the UNIX/POSIX threading framework initially and then port it to other platforms (Windows, etc.) if need be. Does anyone have any thoughts in this issue? Would whatever gains I receive by exploiting concurrency be nullified by the portability issues that will inevitably arise? (On that note, am I really correct in my assumption that I would experience great performance gains with a concurrent garbage collector?) Should I move forward with this strategy or step away from it?

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  • Clients with multiple proxy and multithreading callbacks

    - by enzom83
    I created a sessionful web service using WCF, and in particular I used the NetTcpBinding binding. In addition to methods to initiate and terminate a session, other methods allow the client to send to one or more tasks to be performed (the results are returned via callback, so the service is duplex), but they also allow you to know the status of the service. Assuming you activate the same service on multiple endpoints, and assuming that the client knows these endpoints (for example, it could maintain a List of endpoints), the client should connect with one or more replicas of the same service. The client periodically updates the status of the service, so when it needs to perform a new task (the task is submitted by the user via UI), it selects the service currently less loaded and sends the task to it. Periodically, the client also initiates a maintenance procedure in order to disconnect from one or more overloaded service and in order to connect with new services. I created a client proxy using the svcutil tool. I wish each proxy can be used simultaneously by different threads, for example, in addition to the thread that submits the tasks using a proxy, there are also the following two threads which act periodically: a thread that periodically sends a request to the service in order to obtain the updated state; a thread that periodically selects a proxy to close and instantiates a new proxy to replace the closed one. To achieve these objectives, is it sufficient to create an array of proxies and manage their opening and closing in separate threads? I think I read that the proxy method calls are thread safe, so I would not need to perform a lock before requesting updates to the service. However, when the maintenance procedure (which is activated on its own thread) decides to close a proxy, should I perform a lock? Finally, each proxy is also associated with an object that implements the callback interface for the service: are the callbacks (invoked on the client) executed on different threads on the client? I would like to wrap the management of the proxy in one or more classes so that it can then easily manage within a WPF application.

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  • Multithreading synchronization interview question: Find n words given m threads

    - by rplusg
    I came across this question: You are given a paragraph , which contain n number of words, you are given m threads. What you need to do is , each thread should print one word and give the control to next thread, this way each thread will keep on printing one word , in case last thread come, it should invoke the first thread. Printing will repeat until all the words are printed in paragraph. Finally all threads should exit gracefully. What kind of synchronization will use? I strongly feel we cannot take any advantage of threads here but interviewer is trying to understand my synchronization skills? No need of code, just put some thoughts. I will implement by myself.

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  • Why is multithreading often preferred for improving performance?

    - by user1849534
    I have a question, it's about why programmers seems to love concurrency and multi-threaded programs in general. I'm considering 2 main approaches here: an async approach basically based on signals, or just an async approach as called by many papers and languages like the new C# 5.0 for example, and a "companion thread" that manages the policy of your pipeline a concurrent approach or multi-threading approach I will just say that I'm thinking about the hardware here and the worst case scenario, and I have tested this 2 paradigms myself, the async paradigm is a winner at the point that I don't get why people 90% of the time talk about multi-threading when they want to speed up things or make a good use of their resources. I have tested multi-threaded programs and async program on an old machine with an Intel quad-core that doesn't offer a memory controller inside the CPU, the memory is managed entirely by the motherboard, well in this case performances are horrible with a multi-threaded application, even a relatively low number of threads like 3-4-5 can be a problem, the application is unresponsive and is just slow and unpleasant. A good async approach is, on the other hand, probably not faster but it's not worst either, my application just waits for the result and doesn't hangs, it's responsive and there is a much better scaling going on. I have also discovered that a context change in the threading world it's not that cheap in real world scenario, it's in fact quite expensive especially when you have more than 2 threads that need to cycle and swap among each other to be computed. On modern CPUs the situation it's not really that different, the memory controller it's integrated but my point is that an x86 CPUs is basically a serial machine and the memory controller works the same way as with the old machine with an external memory controller on the motherboard. The context switch is still a relevant cost in my application and the fact that the memory controller it's integrated or that the newer CPU have more than 2 core it's not bargain for me. For what i have experienced the concurrent approach is good in theory but not that good in practice, with the memory model imposed by the hardware, it's hard to make a good use of this paradigm, also it introduces a lot of issues ranging from the use of my data structures to the join of multiple threads. Also both paradigms do not offer any security abut when the task or the job will be done in a certain point in time, making them really similar from a functional point of view. According to the X86 memory model, why the majority of people suggest to use concurrency with C++ and not just an async approach ? Also why not considering the worst case scenario of a computer where the context switch is probably more expensive than the computation itself ?

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  • Multithreading 2D gravity calculations

    - by Postman
    I'm building a space exploration game and I've currently started working on gravity ( In C# with XNA). The gravity still needs tweaking, but before I can do that, I need to address some performance issues with my physics calculations. This is using 100 objects, normally rendering 1000 of them with no physics calculations gets well over 300 FPS (which is my FPS cap), but any more than 10 or so objects brings the game (and the single thread it runs on) to its knees when doing physics calculations. I checked my thread usage and the first thread was killing itself from all the work, so I figured I just needed to do the physics calculation on another thread. However when I try to run the Gravity.cs class's Update method on another thread, even if Gravity's Update method has nothing in it, the game is still down to 2 FPS. Gravity.cs public void Update() { foreach (KeyValuePair<string, Entity> e in entityEngine.Entities) { Vector2 Force = new Vector2(); foreach (KeyValuePair<string, Entity> e2 in entityEngine.Entities) { if (e2.Key != e.Key) { float distance = Vector2.Distance(entityEngine.Entities[e.Key].Position, entityEngine.Entities[e2.Key].Position); if (distance > (entityEngine.Entities[e.Key].Texture.Width / 2 + entityEngine.Entities[e2.Key].Texture.Width / 2)) { double angle = Math.Atan2(entityEngine.Entities[e2.Key].Position.Y - entityEngine.Entities[e.Key].Position.Y, entityEngine.Entities[e2.Key].Position.X - entityEngine.Entities[e.Key].Position.X); float mult = 0.1f * (entityEngine.Entities[e.Key].Mass * entityEngine.Entities[e2.Key].Mass) / distance * distance; Vector2 VecForce = new Vector2((float)Math.Cos(angle), (float)Math.Sin(angle)); VecForce.Normalize(); Force = Vector2.Add(Force, VecForce * mult); } } } entityEngine.Entities[e.Key].Position += Force; } } Yeah, I know. It's a nested foreach loop, but I don't know how else to do the gravity calculation, and this seems to work, it's just so intensive that it needs its own thread. (Even if someone knows a super efficient way to do these calculations, I'd still like to know how I COULD do it on multiple threads instead) EntityEngine.cs (manages an instance of Gravity.cs) public class EntityEngine { public Dictionary<string, Entity> Entities = new Dictionary<string, Entity>(); public Gravity gravity; private Thread T; public EntityEngine() { gravity = new Gravity(this); } public void Update() { foreach (KeyValuePair<string, Entity> e in Entities) { Entities[e.Key].Update(); } T = new Thread(new ThreadStart(gravity.Update)); T.IsBackground = true; T.Start(); } } EntityEngine is created in Game1.cs, and its Update() method is called within Game1.cs. I need my physics calculation in Gravity.cs to run every time the game updates, in a separate thread so that the calculation doesn't slow the game down to horribly low (0-2) FPS. How would I go about making this threading work? (any suggestions for an improved Planetary Gravity system are welcome if anyone has them) I'm also not looking for a lesson in why I shouldn't use threading or the dangers of using it incorrectly, I'm looking for a straight answer on how to do it. I've already spent an hour googling this very question with little results that I understood or were helpful. I don't mean to come off rude, but it always seems hard as a programming noob to get a straight meaningful answer, I usually rather get an answer so complex I'd easily be able to solve my issue if I understood it, or someone saying why I shouldn't do what I want to do and offering no alternatives (that are helpful). Thank you for the help!

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  • What's the current best practice for C multithreading?

    - by Dexter
    I've been a Java (and PHP) developer for most of my life, but will need to use C for my next project. I remember some basic stuff we did back in school with fork, pthread, semaphores, etc. but I'm not sure if that's still the "way to go" here, or if there have been any recent developments/improvements etc. Google's results seem to be fairly dated. Or does that just mean that this is still the current "state of the art"? Or will I have to use a (system-independent) libary like glib if I want higher-level abstractions, like synchronized queues? What other libraries are there? (The programm will only have to run on Linux though)

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  • Installing PIL (Python Imaging Library) in Win7 64 bits, Python 2.6.4

    - by Rafael Almeida
    I'm trying to install said library for use with Python. I tried downloading the executable installer for Windows, which runs, but says it doesn't find a Python installation. Then tried registering (http://effbot.org/zone/python-register.htm) Python, but the script says it can't register (although the keys appear in my register). Then I tried downloading the source package: I run the setup.py build and it works, but when I run setup.py install it says the following: running install running build running build_py running build_ext building '_imaging' extension error: Unable to find vcvarsall.bat What can I do?

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