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  • Order of imports in C#

    - by BrianK
    How do you like to arrange your "using xxx" imports in C#? I got bored the other day and put them in order from shortest to longest. using System; using System.Web; using System.Data; using System.Linq; using System.Web.UI; using Telerik.Web.UI; using System.Drawing; using System.Collections; using System.Configuration; using System.Web.UI.WebControls; using System.Collections.Generic; Brian

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  • set proxy for vpn server on ubuntu server 12.4

    - by Morteza Soltanabadiyan
    I have a vpn server with HTTPS, L2TP , OPENVPN , PPTP. i want to set proxy in the server so all connection that comes from vpn clients use the proxy that i set in my server. I made a bash script file for it , but proxy not working. gsettings set org.gnome.system.proxy mode 'manual' gsettings set org.gnome.system.proxy.http enabled true gsettings set org.gnome.system.proxy.http host 'cproxy.anadolu.edu.tr' gsettings set org.gnome.system.proxy.http port 8080 gsettings set org.gnome.system.proxy.http authentication-user 'admin' gsettings set org.gnome.system.proxy.http authentication-password 'admin' gsettings set org.gnome.system.proxy use-same-proxy true export http_proxy=http://admin:[email protected]:8080 export https_proxy=http://admin:[email protected]:8080 export HTTP_PROXY=http://admin:[email protected]:8080 export HTTPS_PROXY=http://admin:[email protected]:8080 Now , I don't know what to do to make a global proxy for server and all vpn clients use it automatically.

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  • minidlna and samsung tv file format doesn't support

    - by Vasya
    I have PC with XUbuntu 12.04 and Samsung 27A950, so I want to use my PC like dlna server. But I can run file of any format on my TV, get error: "File format doesn't support". I try to open *.avi, *.mkv and *.jpg files the same result. In error log I can see: [2013/06/27 12:34:03] upnphttp.c:1907: error: Error opening /home/family/media/file1.mkv [2013/06/27 12:34:06] upnphttp.c:1907: error: Error opening /home/family/media/file2.avi So, I have no idea why it doesn't work. Any suggestions? miniDLNA version: Version 1.24.1-stedy Config file is default, only few directories added. With version of the default Ubuntu repository was the same. Some time ago I tried mediatomb, had the same error.

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  • Do any languages other than haskell/agda have a hindley-milner type system and type classes?

    - by Jimmy Hoffa
    In pondering what gives Haskell such a layer of mental pain in becoming proficient the main thing I can think of are the Monads, Applicatives, Functors, and gaining an intuition to know how a list or maybe will behave in regards to sequence or alternate or bind etc. But why haven't other languages presented these same concepts given the usefulness of monads/applicatives/etc? It occurs to me, type classes are the key, so the question is: Have any languages other than Haskell/Agda actually implemented type classes in the same or similar way?

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  • I cannot update my version 12-04. After installation of 12.04 I get only error reports when I try to update

    - by cees groenewoud
    received report: from Google translate : Could not initialize the package information There was an insoluble problem occurred while initializing the package information. Please this error in the package "update-manager" to report and add the following message to: 'E: Encountered a section with no Package: header E: Problem with Merge List / var/lib/apt/lists/nl.archive.ubuntu.com_ubuntu_dists_precise_main_i18n_Translation-en, E: The package lists or status file could not decompose or not be opened. " Kon de pakketinformatie niet initialiseren Er heeft zich een onoplosbaar probleem voorgedaan bij het initialiseren van de pakketinformatie. Gelieve deze fout in het pakket ‘update-manager’ te rapporteren en voeg de volgende foutmelding toe: 'E:Encountered a section with no Package: header, E:Problem with MergeList /var/lib/apt/lists/nl.archive.ubuntu.com_ubuntu_dists_precise_main_i18n_Translation-en, E:De pakketlijsten of het statusbestand konden of niet ontleed, of niet geopend worden.'

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  • Live Meeting error: malformed email address... or IS IT???

    - by PeterBrunone
    During a remote SharePoint training session this morning, Live Meeting presented one of our instructors with the following gem:  "An attendee email address is malformed".  This was particularly troubling since a wizard took care of adding all the entries, and they looked correct (even after being sifted through my character analysis tool).As it turns out, the addresses were indeed correct.  As sometimes happens, though, at the line breaks, it looked like there was no space between the semicolon and the following email address.  Since I'm a member in good standing of the "I wonder what this button does" school of thought, I added an extra space after each of these cramped little semicolons -- and the invitation executed flawlessly.Coincidence?  Maybe... but you can bet I'm going to keep trying dumb stuff like that when the error message doesn't make sense.  Think of it as the tech support equivalent of "Ask a silly question..."

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  • twitter api is throwing exception "# is not a valid value for Int32" while getting freinds

    - by vakas
    i am using the api twitterizer.framework while getting the friends of a user the api starts throwing this error. "# is not a valid value for Int32. --- System.ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: startIndex at System.ParseNumbers.StringToInt(String s, Int32 radix, Int32 flags, Int32* currPos) at System.Convert.ToInt32(String value, Int32 fromBase) at System.ComponentModel.Int32Converter.FromString(String value, Int32 radix) at System.ComponentModel.BaseNumberConverter.ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, Object value) --- End of inner exception stack trace --- at System.ComponentModel.BaseNumberConverter.ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, Object value) at System.ComponentModel.TypeConverter.ConvertFromString(ITypeDescriptorContext context, CultureInfo culture, String text) at System.Drawing.ColorConverter.ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, Object value) at System.ComponentModel.TypeConverter.ConvertFromString(String text) at System.Drawing.ColorTranslator.FromHtml(String htmlColor) at Twitterizer.Framework.TwitterRequest.ParseUserNode(XmlNode element) in C:\Projects\twitterizer\Twiterizer.Framework\TwitterRequest.cs:line 514 at Twitterizer.Framework.TwitterRequest.ParseUsers(XmlElement element) in C:\Projects\twitterizer\Twiterizer.Framework\TwitterRequest.cs:line 483 at Twitterizer.Framework.TwitterRequest.ParseResponseData(TwitterRequestData data) in C:\Projects\twitterizer\Twiterizer.Framework\TwitterRequest.cs:line 305" how to handle this?

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  • Problem in migrating to LAMP from XAMPP.. Memory limit error

    - by Geshan
    I was using XAMPP for my local machine but as I wanted to run applications like mysql work bench and some test frameworks I decided to switch to LAMP self install. I'm using ubuntu and followed the instructions at: https://help.ubuntu.com/community/ApacheMySQLPHP But the problem is LAMP is consuming too much of my memory (RAM) I've allocated 124 MB currently but still it gives me memory exhausted error when I run Drush (Drupal command line). When I do drush cc to clear cache it give me the following: Fatal error: Allowed memory size of 33554432 bytes exhausted (tried to allocate 122880 bytes) in /var/www/----/sites/all/modules/ubercart/uc_order/uc_order.order_pane.inc on line 150 Call Stack: 0.0020 185624 1. {main}() /opt/drush/drush.php:0 0.0254 1303672 2. drush_main() /opt/drush/drush.php:37 0.2674 5107784 3. drush_bootstrap() /opt/drush/drush.php:71 0.2676 5109872 4. _drush_bootstrap_drupal_full() /opt/drush/includes/environment.inc:173 0.2676 5151032 5. drupal_bootstrap() /opt/drush/includes/environment.inc:655 0.3030 7739048 6. _drupal_bootstrap() /var/www/missmoti/includes/bootstrap.inc:989 0.3122 8855792 7. _drupal_bootstrap_full() /var/www/missmoti/includes/bootstrap.inc:1078 0.3445 12387320 8. module_load_all() /var/www/missmoti/includes/common.inc:2608 0.5194 32586544 9. drupal_load() /var/www/missmoti/includes/module.inc:14 0.5251 33361112 10. include_once('/var/www/missmoti/sites/all/modules/ubercart/uc_order/uc_order.module') /var/www/-----/includes/bootstrap.inc:617 Drush command could not be completed. In each error it shows me a back trace and I guess this default debugger I'm not aware of in Apache or my PHP config it eating up the memory. If anyone can help I"d be glad. Another error below: Fatal error: Call to undefined function dsm() in /var/www/-----/sites/all/modules/custom/gtpath/gtpath.module on line 180 Call Stack # Time Memory Function Location 1 0.0002 120144 {main}( ) ../index.php:0 2 1.7604 68224112 theme( ) ../index.php:36 3 2.0188 77346112 call_user_func_array ( ) ../theme.inc:658 4 2.0188 77347024 gtpath_preprocess_page( ) ../theme.inc:0 how do I deal with this default debugger? how do I turn it off??

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  • Why do I get the result zero when I try to get the width of a DropDownList control in asp.net?

    - by Paul Jack
    After I click button1, it display 0, why? How can get correct width of a DropDownList control? Thanks! <%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default2.aspx.cs" Inherits="Default2" % Item 1 Item 2 </div> </form> using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; public partial class Default2 : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { } protected void Button1_Click(object sender, EventArgs e) { Button1.Text = DropDownList1.Width.Value.ToString(); } }

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  • .NET 4.0 Fails When sending emails with attachments larger than 3MB

    - by JL
    I recently had an issue after upgrading my .net framework to 4.0 from 3.5: System.Net.Mail.SmtpException: Failure sending mail. --- System.IndexOutOfRangeException: Index was outside the bounds of the array. at System.Net.Base64Stream.EncodeBytes(Byte[] buffer, Int32 offset, Int32 count, Boolean dontDeferFinalBytes, Boolean shouldAppendSpaceToCRLF) at System.Net.Base64Stream.Write(Byte[] buffer, Int32 offset, Int32 count) at System.Net.Mime.MimePart.Send(BaseWriter writer) at System.Net.Mime.MimeMultiPart.Send(BaseWriter writer) at System.Net.Mail.Message.Send(BaseWriter writer, Boolean sendEnvelope) at System.Net.Mail.SmtpClient.Send(MailMessage message) --- End of inner exception stack trace --- I read this connect bug listing here: http://connect.microsoft.com/VisualStudio/feedback/details/544562/cannot-send-e-mails-with-large-attachments-system-net-mail-smtpclient-system-net-mail-mailmessage. If anyone cares about this issue, please vote for it on Connect, so it will be fixed sooner.

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  • Does there exist an "idea checkout system" on the Internet?

    - by TimeSpace Traveller
    Greetings. I would like to ask the following question: is there anything on the Internet like an "idea checkout" system? Situation: I'm a software developer. Since my current job has started 2 years ago, my mentor at that time has pointed me to the open source world. I have only put little time to look at some of the open source projects, let alone any contribution. However, it is my wish to start developing something outside of the work. Well, except a little problem. I don't know what to develop! It is not about the technical knowledge; the problem is that, I am not a creative person. I am very good at analytical thinking, as well as debugging skills. When being told by my work partners to develop a solution, I could get it done without a problem. However, outside of work, I have no idea what to develop. When I look at the Internet, it seems that so many people have already been developing on so many interesting stuff, making me wonder what I could develop, so that I would not reinvent something already existed. That starts to make me wonder. On the Internet, is there anything like an "idea checkout" system or society? For example, some people would throw in as a software idea, and the system would keep it as an "inventory"; later, a potential software developer would "check out" the idea, just a how people would check out a book from the library. Then, the developer would check the "idea" back in, with a certain kind of work-in-progress or developed software, thus becoming an open-source project. I have just noticed that here at stackoverflow, there is a "Project-Ideas" tag, so perhaps that can provide me some ideas on what to develop; still, my wonder is about a system that people would provide ideas, and people would check out ideas to develop / implement into actual solution. Is there such a system or society existing anywhere on the Internet? Any input is welcome! Thank you very much. Update: Thank you for everyone who has answered my question. Certainly, "getting idea" is part of my problem; as a software developer, however, I'm concerned more than just "getting idea". What I am concerned more, as I have commented, is about the existence of such an idea exchanging ecosystem, capable to initiate open-source projects. I'll put an example here. Say, person A has an idea of music search program, but not search by the attributes of the music (composer, singer, publisher, lyrics, etc.); instead, he wants a program (and a database) to search a piece of music by melody. Very often, people only remember a piece of music by its melody, not even the name of the music (e.g. the music he wants was only once heard in a bookstore, but the melody just gets stuck in his head!). In order to find that piece, normally he would just need to blindly search for it, and spent a long time to do so. A search by melody would enable person A to find the piece much quicker. However, he would not want to personally work on it, not just because of the complexity (he is not a musician and/or programmer, knowing almost nothing about music systems in computer, search algorithms, etc.), but also legal issues (RIAA??), thus he would just like to keep the idea at some place, and let other people to work on that. Now, a developer (person B) may be at the same stage as I am right now, wishing to find something to develop, but not having an idea. With the idea exchanging ecosystem, person B will search, and somehow discover person A's music search idea, and feeling interested enough to work on it. So he "checks out" the idea, start working on it (at least a skeleton), and checks back in with the progress. An open-source project starts from here, fulfilling person A's wish, and person B's programming desire. The above is just an example, because there are already such systems exist on the Internet, but it illustrates what I think about the idea exchange system in my mind. My main concern is about idea exchanging ecosystem, not at personal and unorganized level, but at a semi-organized protocol that's specifically for software developers, having actual projects coming out as the fruits. Not about "projects", but about "ideas and product of ideas". Hopefully that would clear up some of the original idea of this question. Any input is welcome; in fact, I would like to hear as many people as possible how everyone thinks about this. Thank you very much!

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  • ASP.NET MVC 3 Linq uppercase or lowercase database search

    - by user1495557
    I need immediate help. ): and i know little english. ASP.NET MVC 3 Linq uppercase or lowercase contains search Example: string metin="baris"; var IcerikAra = (from icerik in Context.dbDokumanEditor join kategori in Context.dbDokumanKategori on icerik.KategoriID equals kategori.KategoriID where icerik.Icerik.toLower().Contains(metin) select new { KategoriID=kategori. KategoriAd=kategori.KategoriAd }).ToList(); Exception: StackTrace: at System.Data.EntityClient.EntityCommandDefinition.ExecuteStoreCommands(EntityCommandentityCommand, CommandBehavior behavior) at System.Data.Objects.Internal.ObjectQueryExecutionPlan.Execute[TResultType](ObjectContext context, ObjectParameterCollection parameterValues) at System.Data.Objects.ObjectQuery`1.GetResults(Nullable`1 forMergeOption) at System.Data.Objects.ObjectQuery`1.System.Collections.Generic.IEnumerable.GetEnumerator() at System.Data.Entity.Internal.Linq.InternalQuery`1.GetEnumerator() at System.Data.Entity.Infrastructure.DbQuery`1.System.Collections.Generic.IEnumerable.GetEnumerator() at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection) at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source) at Plus.Areas.DokumanEditor.Controllers.DokumanController.DokumanIcerikAramaBaslat(String metin) Error Message: An error occurred while executing the command definition. See the inner exception for details. thanks..

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  • fcgio.cpp: In destructor 'virtual fcgi_streambuf::~fcgi_streambuf()':

    - by skyeagle
    I am attempting to build fastcgi on a Linux Ubuntu 10.x machine. I run the following commands: ./configure make and I get the following error: fcgio.cpp: In destructor 'virtual fcgi_streambuf::~fcgi_streambuf()': fcgio.cpp:50: error: 'EOF' was not declared in this scope fcgio.cpp: In member function 'virtual int fcgi_streambuf::overflow(int)': fcgio.cpp:70: error: 'EOF' was not declared in this scope fcgio.cpp:75: error: 'EOF' was not declared in this scope fcgio.cpp: In member function 'virtual int fcgi_streambuf::sync()': fcgio.cpp:86: error: 'EOF' was not declared in this scope fcgio.cpp:87: error: 'EOF' was not declared in this scope fcgio.cpp: In member function 'virtual int fcgi_streambuf::underflow()': fcgio.cpp:107: error: 'EOF' was not declared in this scope make[2]: *** [fcgio.lo] Error 1 make[2]: Leaving directory `/somepath/fcgi-2.4.0/libfcgi' make[1]: *** [all-recursive] Error 1 make[1]: Leaving directory `/somepath/fcgi-2.4.0' make: *** [all] Error 2 I notice that others have had the same problem and have asked this question in various fora etc - however, I have not as yet, seen an answer to this question/problem. Has anyone ever managed to build fastcgi on Linux? How do I fix this problem?

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  • Can I flip the coordinate system without flipping text in iTextSharp?

    - by I. J. Kennedy
    I have some chart-creating code written for a coordinate system in which a y-coordinate of 0 is the top of the page. We are now converting to iTextSharp, which uses the conventional system from mathematics where a y-coordinate of 0 is the bottom of the page. There are many calculations involved in producing the chart and I'd like to not mess with those calculations. I can partially "fix" the problem by transforming iTextSharp's coordinate system like this: pdfContentByte.ConcatCTM(1f, 0f, 0f, -1f, 0f, pdfDoc.PageSize.Height); This works great for lines, rectangles, and circles, but the text is now upside down! Is there a way to remedy this, using SetTextMatrix or otherwise?

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  • How to solve such system with given parts of it? (maple)

    - by Kabumbus
    So I had a system #for given koefs k:=3; n:=3; #let us solve system: koefSolution:= solve({ sum(a[i], i = 0 .. k) = 0, sum(a[i], i = 0 .. k)-(sum(b[i], i = 0 .. k)) = 0, sum(i^n*a[i], i = 0 .. k)-(sum(i^(n-1)*b[i], i = 0 .. k)) = 0 }); So I have a vector like koefSolution := { a[0] = 7*a[2]+26*a[3]-b[1]-4*b[2]-9*b[3], a[1] = -8*a[2]-27*a[3]+b[1]+4*b[2]+9*b[3], a[2] = a[2], a[3] = a[3], b[0] = -b[1]-b[2]-b[3], b[1] = b[1], b[2] = b[2], b[3] = b[3]} I have a[0] so I try solve({koefSolution, a[0] = 1}); why it does not solve my system for given a[0]? ( main point here is to fill koefSolution with given a[] and b[] and optimize.)

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  • How do I start xterm with a headless system?

    - by NeViXa
    I'm running Ubuntu 12.04 and I want to boot directly and headless in the terminal (no GUI). After that I want to startx to start a program in xterm. When I boot 'headed', everything is working like supposed to, but: - When I boot headless, startx is not working (no screens found) I already tried to change xorg.conf to below, but it didn't not work: Section "Device" Identifier "VNC Device" Driver "vesa" EndSection Section "Screen" Identifier "VNC Screen" Device "VNC Device" Monitor "VNC Monitor" SubSection "Display" Modes "1280x1024" EndSubSection EndSection Section "Monitor" Identifier "VNC Monitor" HorizSync 30-70 VertRefresh 50-75 EndSection How can I boot headless and still be able to run startx? ANSWER: Adding the BusID to the Devices section in the xorg.conf above, fixed the problem for me. BusID "PCI:1:00:1"

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  • Invalid Viewstate

    - by murak
    I always got this error guys on my site.Anybody got a solution. Stacktrace at System.Web.UI.Page.DecryptStringWithIV(String s, IVType ivType) at System.Web.UI.Page.DecryptString(String s) at System.Web.Handlers.ScriptResourceHandler.DecryptParameter(NameValueCollection queryString) at System.Web.Handlers.ScriptResourceHandler.ProcessRequestInternal(HttpResponse response, NameValueCollection queryString, VirtualFileReader fileReader) at System.Web.Handlers.ScriptResourceHandler.ProcessRequest(HttpContext context) at System.Web.Handlers.ScriptResourceHandler.System.Web.IHttpHandler.ProcessRequest(HttpContext context) at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) Query String d=J_c3w3Q59U-PnoRlWBPOJMVgHe_9Ile9wANEXiRFLzG8mequestManager._initialize('ctl00%24ScriptManager1' I noticed that there are strings that got appended on the last part of ScriptResource.axd which are not part of the querystring(equestManager._initialize('ctl00%24ScriptManager1').I don't know how this string ends up here.I am using MS ajax, webforms and IIS7 on a shared hosting plan.

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  • CFMX6.1 deplying on Websphere 6.1 Server: Error 500: The Security service is not available.

    - by ahiru
    I am deploying a CFMX6.1 application to a Websphere 6.1 server. The server starts up without any errors but when I goto the CF Adminstrator page (or any cf page) I get the following error: Error 500: The Security service is not available. Can you deploy CFMX6.1 to WS6.1? My searches on the internets seem to say yes and no. As far as the error goes I normally end up at a page that lists the same error with stacktrace but no answers. Am I just searching using the wrong question? Thanks.

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  • How can I find the places of system calls of my program?

    - by Lucky Man
    From strace manual: -i Print the instruction pointer at the time of the system call. I straced my programm: strace -i prog As a result I got a lot of system calls. One of them: [000da49c] open("./rabbit.o", O_RDONLY) = 3 But disassembled instruction at this address of prog doesn't call any syscall (hte editor): da49c ! mov r7, ip What is wrong? How can I find the places of system calls of my program? P.S. Architecture of my device doesn't support GDB-command catch syscall.

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  • How do I install the Intel Graphics driver in my system?

    - by John
    Can someone help me out and explain or point me in the right direction on how to check video drivers and see if my video card running okay? I had 10.04 installed on my Thinkpad r61 with Compiz Manager and life was great, until the machine took water damage. I bought an ASUS (X54H) since and am trying out 12.04, but the desktop just doesn't look right. I always struggled with video driver installation. There are no proprietary drivers available in the hardware manager. When I run lspci | grep VGA: 00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09) I will greatly appreciate your help. I want to use Linux more, but like I said video drivers appear to be my biggest concern. I have also tried 12.04 on my desktop PC, but again failed to configure video card, so switched back to Windows 7.

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  • Problem with deploying django application on mod_wsgi

    - by Shehzad009
    Hello, I seem to have a problem deploying django with mod_wsgi. In the past I've used mod_python but I want to make the change. I have been using Graham Dumpleton notes here http://code.google.com/p/modwsgi/wiki/IntegrationWithDjango1, but it still seem to not work. I get a Internal Server Error. django.wsgi file: import os import sys sys.path.append('/var/www/html') sys.path.append('/var/www/html/c2duo_crm') os.environ['DJANGO_SETTINGS_MODULE'] = 'c2duo_crm.settings' import django.core.handlers.wsgi application = django.core.handlers.wsgi.WSGIHandler() WSGIScriptAlias / /var/www/html/c2duo_crm/apache/django.wsgi Apache httpd file: <Directory /var/www/html/c2duo_crm/apache> Order allow,deny Allow from all </Directory> In my apache error log, it says I have this error This is not all of it, but I've got the most important part: [Errno 13] Permission denied: '/.python-eggs' [Thu Mar 03 14:59:25 2011] [error] [client 127.0.0.1] [Thu Mar 03 14:59:25 2011] [error] [client 127.0.0.1] The Python egg cache directory is currently set to: [Thu Mar 03 14:59:25 2011] [error] [client 127.0.0.1] [Thu Mar 03 14:59:25 2011] [error] [client 127.0.0.1] /.python-eggs [Thu Mar 03 14:59:25 2011] [error] [client 127.0.0.1] [Thu Mar 03 14:59:25 2011] [error] [client 127.0.0.1] Perhaps your account does not have write access to this directory? You can [Thu Mar 03 14:59:25 2011] [error] [client 127.0.0.1] change the cache directory by setting the PYTHON_EGG_CACHE environment [Thu Mar 03 14:59:25 2011] [error] [client 127.0.0.1] variable to point to an accessible directory.

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  • Best Creational Pattern for loggers in a multi-threaded system?

    - by Dipan Mehta
    This is a follow up question on my past questions : Concurrency pattern of logger in multithreaded application As suggested by others, I am putting this question separately. As the learning from the last question. In a multi-threaded environment, the logger should be made thread safe and probably asynchronous (where in messages are queued while a background thread does writing releasing the requesting object thread). The logger could be signleton or it can be a per-group logger which is a generalization of the above. Now, the question that arise is how does logger should be assigned to the object? There are two options I can think of: 1. Object requesting for the logger: Should each of the object call some global API such as get_logger()? Such an API returns "the" singleton or the group logger. However, I feel this involves assumption about the Application environment to implement the logger -which I think is some kind of coupling. If the same object needs to be used by other application - this new application also need to implement such a method. 2. Assign logger through some known API The other alternative approach is to create a kind of virtual class which is implemented by application based on App's own structure and assign the object sometime in the constructor. This is more generalized method. Unfortunately, when there are so many objects - and rather a tree of objects passing on the logger objects to each level is quite messy. My question is there a better way to do this? If you need to pick any one of the above, which approach is would you pick and why? Other questions remain open about how to configure them: How do objects' names or ID are assigned so that will be used for printing on the log messages (as the module names) How do these objects find the appropriate properties (such as log levels, and other such parameters) In the first approach, the central API needs to deal with all this varieties. In the second approach - there needs to be additional work. Hence, I want to understand from the real experience of people, as to how to write logger effectively in such an environment.

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  • Yippy &ndash; the F# MVVM Pattern

    - by MarkPearl
    I did a recent post on implementing WPF with F#. Today I would like to expand on this posting to give a simple implementation of the MVVM pattern in F#. A good read about this topic can also be found on Dean Chalk’s blog although my example of the pattern is possibly simpler. With the MVVM pattern one typically has 3 segments, the view, viewmodel and model. With the beauty of WPF binding one is able to link the state based viewmodel to the view. In my implementation I have kept the same principles. I have a view (MainView.xaml), and and a ViewModel (MainViewModel.fs).     What I would really like to illustrate in this posting is the binding between the View and the ViewModel so I am going to jump to that… In Program.fs I have the following code… module Program open System open System.Windows open System.Windows.Controls open System.Windows.Markup open myViewModels // Create the View and bind it to the View Model let myView = Application.LoadComponent(new System.Uri("/FSharpWPF;component/MainView.xaml", System.UriKind.Relative)) :?> Window myView.DataContext <- new MainViewModel() :> obj // Application Entry point [<STAThread>] [<EntryPoint>] let main(_) = (new Application()).Run(myView) You can see that I have simply created the view (myView) and then created an instance of my viewmodel (MainViewModel) and then bound it to the data context with the code… myView.DataContext <- new MainViewModel() :> obj If I have a look at my viewmodel (MainViewModel) it looks like this… module myViewModels open System open System.Windows open System.Windows.Input open System.ComponentModel open ViewModelBase type MainViewModel() = // private variables let mutable _title = "Bound Data to Textbox" // public properties member x.Title with get() = _title and set(v) = _title <- v // public commands member x.MyCommand = new FuncCommand ( (fun d -> true), (fun e -> x.ShowMessage) ) // public methods member public x.ShowMessage = let msg = MessageBox.Show(x.Title) () I have exposed a few things, namely a property called Title that is mutable, a command and a method called ShowMessage that simply pops up a message box when called. If I then look at my view which I have created in xaml (MainView.xaml) it looks as follows… <Window xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="F# WPF MVVM" Height="350" Width="525"> <Grid> <Grid.RowDefinitions> <RowDefinition Height="Auto"/> <RowDefinition Height="Auto"/> <RowDefinition Height="*"/> </Grid.RowDefinitions> <TextBox Text="{Binding Path=Title, Mode=TwoWay}" Grid.Row="0"/> <Button Command="{Binding MyCommand}" Grid.Row="1"> <TextBlock Text="Click Me"/> </Button> </Grid> </Window>   It is also very simple. It has a button that’s command is bound to the MyCommand and a textbox that has its text bound to the Title property. One other module that I have created is my ViewModelBase. Right now it is used to store my commanding function but I would look to expand on it at a later stage to implement other commonly used functions… module ViewModelBase open System open System.Windows open System.Windows.Input open System.ComponentModel type FuncCommand (canExec:(obj -> bool),doExec:(obj -> unit)) = let cecEvent = new DelegateEvent<EventHandler>() interface ICommand with [<CLIEvent>] member x.CanExecuteChanged = cecEvent.Publish member x.CanExecute arg = canExec(arg) member x.Execute arg = doExec(arg) Put this all together and you have a basic project that implements the MVVM pattern in F#. For me this is quite exciting as it turned out to be a lot simpler to do than I originally thought possible. Also because I have my view in XAML I can use the XAML designer to design forms in F# which I believe is a much cleaner way to go rather than implementing it all in code. Finally if I look at my viewmodel code, it is actually quite clean and compact…

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