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  • Activator.CreateInstance uses a huge amount of memory

    - by Marco
    I have been playing a bit with Silverlight and try to port my Silverlight 3.0 application to Silverlight 4.0. My application loads different XAP files and upon a user request create an instance of a Xaml user control and adds it to the main container, in a sort of MEF approach in order I can have an extensible and pluggable application. The application is pretty huge and to keep acceptable the performances and the initial loading I have built up some helper classes to load in the background all pages and user controls that might be used later on. On Silverlight 3.0 everything was running smoothly without any problem so far. Switching to SL 4.0 I have noticed that when the process approaches to create the instances of the user controls using Activator.CreateInstance, the layout freezes unexpectedly for a minute and sometimes for more. Looking at the task manager the memory usage of IE jumps from 50MB to 400MB and sometimes to 1.5 GB. If the process won't take that much the layout is rendered properly and the memory falls back to 50 MB. Otherwise everything crashes due to out of memory exeption. Does anybody encountered the same problem? Or has anybody a solution about this tricky issue?

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  • Can foreground threads be aborted on application shutdown in C#.Net?

    - by Cartman
    I inherited a c# winforms app (.NET 2.0) which creates a thread upon startup in a singleton class. This thread handles messages from a messaging topic (Tibco EMS). When the app is shutdown, the thread doesn't remain the the background? How is this possible? Is there something else happening that can abort this thread? Code snippet: public class Startup { public static void main(string [] args) { MySingletonClass.Instance.Init(); // do other things below Application.Run(new MainForm()); } public class MySingletonClass { // singleton code //.. //.. private Thread t; public void Init() { t = new Thread(new ThreadStart(poll)); } private void poll() { while(true} { // listen for messages and process but there is no break clause // exceptions are also handled within to ensure control doesnt go out } } Pls. don't write to tell me this is bad code. I know it and i was going to refactor it when i realised that the app actually shutdowns correctly inspite of this aberration. So i want to understand how this is possible. Thanks for your help

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  • Help renaming svn repository

    - by rascher
    Here is the deal: I created an SVN repository, say, foo. It is at http://www.example.com/foo. Then I did an svn checkout. I made some updates and changes to my local copy of the code over the week. I haven't committed yet. I realized that I wanted to rename the repository. So I did this: svn copy http://example.com/foo http://example.com/bar svn delete http://example.com/foo I finish my changes (and local svn still thinks I'm working under "foo".) svn commit fails because the repo has been renamed. I try to use svn switch --relocate but it yells at me because svn is awful. I try using the script here to replace "foo" with "bar" in my billion .svn/ folders. This replace is taking a long time. I wonder if something hung? Or maybe sshfs failed? I kill it. Ctrl-C. I look and see that half my files have "foo" and the others have "bar" in the URLs in the sundry .svn/ folders. All I want to do is commit my files with the new name. I could re-checkout the branch, but then I have no way to remember which files I changed, which is why I was using version control in the first place, and svn is so godawful at moving and renaming things. What do I need to do to: Have a "clean" copy of my "bar" svn branch? and, most importantly: Commit the changes I made?

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  • Python - How to wake up a sleeping process- multiprocessing?

    - by user1162512
    I need to wake up a sleeping process ? The time (t) for which it sleeps is calculated as t = D/S . Now since s is varying, can increase or decrease, I need to increase/decrease the sleeping time as well. The speed is received over a UDP procotol. So, how do I change the sleeping time of a process, keeping in mind the following:- If as per the previous speed `S1`, the time to sleep is `(D/S1)` . Now the speed is changed, it should now sleep for the new time,ie (D/S2). Since, it has already slept for D/S1 time, now it should sleep for D/S2 - D/S1. How would I do it? As of right now, I'm just assuming that the speed will remain constant all throughout the program, hence not notifying the process. But how would I do that according to the above condition? def process2(): p = multiprocessing.current_process() time.sleep(secs1) # send some packet1 via UDP time.sleep(secs2) # send some packet2 via UDP time.sleep(secs3) # send some packet3 via UDP Also, as in threads, 1) threading.activeCount(): Returns the number of thread objects that are active. 2) threading.currentThread(): Returns the number of thread objects in the caller's thread control. 3) threading.enumerate(): Returns a list of all thread objects that are currently active. What are the similar functions for getting activecount, enumerate in multiprocessing?

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  • Make password case unsensitive in shared ASP.Net membership tables web ap

    - by bill
    Hi all, i have two webapps.. that share ASP.Net membership tables. Everything works fine except i cannot remove case-sensitivity in one of the apps the way i am doing it in the other. in the non-working app void Login1_LoggingIn(object sender, LoginCancelEventArgs e) { string username = Login1.UserName.Trim(); if (!string.IsNullOrEmpty(username)) { MembershipUser user = Membership.GetUser(username); if (user != null) { // Only adjust the UserName if the password is correct. This is more secure // so a hacker can't find valid usernames if we adjust the case of mis-cased // usernames with incorrect passwords. string password = Login1.Password.ToUpper(); if (Membership.ValidateUser(user.UserName, password)) { Login1.UserName = user.UserName; } } } } is not working. the password is stored as all upper case. Converted at the time the membership user is created! So if the password is PASSWORD, typing PASSWORD allows me to authenticate. but typing password does not! Even though i can see the string being sent is PASSWORD (converted with toUpper()). I am at a complete loss on this.. in the other app i can type in lower or upper or mixed and i am able to authenticate. In the other app i am not using the textboxes from the login control though.. not sure if this is making the difference??

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  • Windows 2008 VPS hosting experiences

    - by Luke Bennett
    Whilst similar questions exist, I couldn't find any which quite match my request. I'm looking for hosting for some personal .NET projects which for various reasons I do not want to host on our servers at work. I need to be able to host multiple sites and for that reason I'm thinking of a VPS with RDP access for the time being - don't fancy shared hosting as I feel that doesn't offer me the flexbility and control I'm looking for. What experiences do people have of Windows 2008 VPS providers? I've come across a few possibilities although it seems a lot of places are still on Windows 2003 with 2008 'coming soon'. Is VPS the best way to go? Eventually (depending on how the projects take off) I intend to get a dedicated box but at this stage it's not cost-effective. Also, what are people's experiences of running SQL Server Express on a VPS? What would you say the minimum requirements are for CPU/memory? I know it's not going to be anywhere near as performant as SQL Server 2005/8 running on a dedicated box but I'm hoping it will be an acceptable starting point. Any other tips/advice also welcome! Edit: Forgot to mention, I'm ideally looking for UK hosting although I'm open to alternatives.

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  • How to check if an entityset is populated

    - by TheQ
    How can i check if an entityset of a linq-object is populated or not? Example code below. My model have two methods, one joins data, and the other does not: public static Member GetMemberWithSettings(Guid memberId) { using (DataContext db = new DataContext()) { DataLoadOptions dataLoadOptions = new DataLoadOptions(); dataLoadOptions.LoadWith<Member>(x => x.Settings); db.LoadOptions = dataLoadOptions; var query = from x in db.Members where x.MemberId == memberId select x; return query.FirstOrDefault(); } } public static Member GetMember(Guid memberId) { using (DataContext db = new DataContext()) { var query = from x in db.Members where x.MemberId == memberId select x; return query.FirstOrDefault(); } } Then my control have the following code: Member member1 = Member.GetMemberWithSettings(memberId); Member member2 = Member.GetMember(memberId); Debug.WriteLine(member1.Settings.Count); Debug.WriteLine(member2.Settings.Count); The last line will generate a "Cannot access a disposed object" exception. I know that i can get rid of that exception just by not disposing the datacontext, but then the last line will generate a new query to the database, and i don't want that. What i would like is something like: Debug.WriteLine((member1.Settings.IsPopulated()) ? member1.Settings.Count : -1); Debug.WriteLine((member2.Settings.IsPopulated()) ? member2.Settings.Count : -1); Is it possible?

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  • Prevent jQuery Tabs to bind to <ul> elements below the main <ul> element.

    - by Shiki
    Hi, I have this HTML: <div id="mytabs"> <ul id="main-tabs"> <li><a href="">Link</a></li> <li><a href="">Link</a></li> <li class="filter"> <ul id="filter-controls"> <li><a href="">Filter by something</a></li> <li><a href="">Filter by something</a></li> <li><a href="">Filter by something</a></li> </ul> </li> </ul> </div> And I set it to a tabbed control: $('#mytabs').tabs(); My problem is jQuery UI also converts the <li> elements in <ul id="filter-controls"> into tabs. Is there a way to instruct jQuery UI to only set the <li> children of <ul id="main-tabs"> as the tabs? Note: I am currently in no position to change <ul id="filter-controls" into a non-ul element.

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  • C Array of string

    - by Meko
    HI. This is maybe simple question but I want to create two dimensional array and add it string like in java string str = "text" ; string [][] array = new [][] string ; array[i][j] = str ; But in C there is no string .I tried like this but here strcpy() gives error.It returns to assembly code. I am trying to read line by line from text and split line by space and add them to structure.But first I think that I must add each line and row in array and then making iteration and adding to structures fields. static const char filename[] = "student.txt"; FILE *file = fopen ( filename, "r" ); char line [ 128 ]; /* or other suitable maximum line size */ char delims [ ]=" "; char *result =NULL; char list[15]; char arra[128][128]; int i=0; int j=0; struct { char gruppa[10]; char familiya[20]; int uchaste; struct { int firsth; int second; int third; int fourht; int fifth; } exam; }student; for(i=0; i<128; i++) for(j=0; j<128; j++) arra[i][j] = '\0'; for(i=0; i<15; i++) list[i] = '\0'; if ( file != NULL ) { while ( fgets ( line, sizeof line, file ) != NULL ) { result = strtok(line,delims); while (result !=NULL) { strcpy(list,("%s",result)); strcpy(arra[i][j],list); // Here it gives errror j++; result = strtok(NULL,delims); } j=0; i++; } fclose ( file ); } else { perror ( filename ); } getchar(); return 0; }

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  • ZendFramework Headscript Helper - Make scripts unique

    - by tokam
    How can I ensure that the headScript and headStyle helper include css files only once when added? The reason I am asking is that I would like to display some contents in a lightbox and all Flashmassages.E.g. notifications like profile successfully edited. To display flashmessages in the lightbox i would like to check at the top of my layout script if they are set, in case they are i would like to attach the required javascript library using the headScript helper. The problem is that I have no control about the scripts which were already added at this point. Maybe at a page where the library is needed for an other use case, it has already been added with addScript. How can I ensure all scripts are added only once to my helper? I already checked that these helpers extend Zend_View_Helper_Placeholder_Container_Standalone which uses an ArrayObject internally to hold the data and provides getters & setter to the array object. Maybe a solution here would be to check each time when adding a script file if it already exists using the ArrayObject?

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  • Why is short project lifetime and other situation-specific reasons used to excuse crappy code? [clos

    - by sharptooth
    Every now and then (including on SO) people say things implying that "if the project is short lived you can leave obvious defects there" or "that memory leak only accounts for 100 bytes per whole program lifetime and could be left". Now in my practice I always reuse company-owned code to the greatest extent I can. Like if I need something and I can find it in the company codebase I take it from there and reuse or adapt. This means that any crappy code will be reused as well and I might notice or not notice defects therein. So the defect in some "test we only need for a month" can slip into a proram we ship to customers. And a leak that "only accounted for 100 bytes per lifetime" now could account for 100 bytes 10 times per second in a server application intended to run for months. That's why I don't understand why excuses like that are offered. Is our compamy the only one having a source control? Or are we the only company that requires writing human-readable code? Could anyone shed a light on why people seriously offer such excuses?

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  • Strange numbers in java socket output

    - by user293163
    I have small test app: Socket socket = new Socket("jeck.ru", 80); PrintWriter pw = new PrintWriter(socket.getOutputStream(), false); pw.println("GET /ip/ HTTP/1.1"); pw.println("Host: jeck.ru"); pw.println(); pw.flush(); BufferedReader rd = new BufferedReader(new InputStreamReader(socket.getInputStream())); String str; while ((str = rd.readLine()) != null) { System.out.println(str); } It`s output: HTTP/1.1 200 OK Date: Sat, 13 Mar 2010 22:06:51 GMT Content-Type: text/html;charset=utf-8 Transfer-Encoding: chunked Connection: keep-alive Keep-Alive: timeout=5 Server HTTP/1.1 200 OK Date: Sat, 13 Mar 2010 22:06:51 GMT Content-Type: text/html;charset=utf-8 Transfer-Encoding: chunked Connection: keep-alive Keep-Alive: timeout=5 Server: Apache Cache-Control: max-age=0 Expires: Sat, 13 Mar 2010 22:06:51 GMT 123 <!DOCTYPE html> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <title>??? IP</title> </head> <body> <div style='text-align: center; font: 32pt Verdana;margin-top: 300px'> ??? IP &#151; 94.103.87.153 </div> </body> </html> 0 Whence these numbers (123 an 0) takes?

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  • CSS of iFramed page not being applied properly

    - by Mike E.
    My company has purchased a third-party package with a built-in customer facing web portal, and I'm being tasked with integrating it into our site. Unfortunately, the web portal does not look great, and we have absolutely no control over how it looks (other than asking the vendor for changes - $$). In order to make it look somewhat like the rest of our site, I've stuck it in an iFrame (I'm not thrilled about this either) to put our logo and top navigation on it. Please note, I am not attempting to manipulate the iframed page in any way. Firefox handles this just fine, but in IE7 and IE8, not all of the CSS is being applied properly when the application's pages are displayed in the iFrame. Specifically, it should be applying a font-family of Arial to all TDs, but some text inside TDs are not being displayed as Arial. Any ideas as to what is going on? This only happens when the pages are viewed inside the iFrame. Outside the iFrame, the CSS is applied as it should be. I'm guessing we're going to have to get our vendor to make some changes, but I'd love to know why the iFrame is impacting the page like this. Thanks!

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  • Any guidelines for handling the Headset and Bluetooth AVRC transport controls in Android 2.2

    - by StefanK
    I am trying to figure out what is the correct (new) approach for handling the Intent.ACTION_MEDIA_BUTTON in Froyo. In pre 2.2 days we had to register a BroadcastReceiver (either permanently or at run-time) and the Media Button events would arrive, as long as no other application intercepts them and aborts the broadcast. Froyo seems to still somewhat support that model (at least for the wired headset), but it also introduces the registerMediaButtonEventReceiver, and unregisterMediaButtonEventReceiver methods that seem to control the "transport focus" between applications. During my experiments, using registerMediaButtonEventReceiver does cause both the bluetooth and the wired headset button presses to be routed to the application's broadcast receiver (the app gets the "transport focus"), but it looks like any change in the audio routing (for example unplugging the headset) shits the focus back to the default media player. What is the logic behind the implementation in Android 2.2? What is correct way to handle transport controls? Do we have to detect the change in the audio routing and try to re-gain the focus? This is an issue that any 3rd party media player on the Android platform has to deal with, so I hope that somebody (probably a Google Engineer) can provide some guidelines that we can all follow. Having a standard approach may make headset button controls a bit more predictable for the end users. Stefan

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  • How can multiple variables be passed to a function cleanly in C?

    - by aquanar
    I am working on an embedded system that has different output capabilities (digital out, serial, analog, etc). I am trying to figure out a clean way to pass many of the variables that will control those functions. I don't need to pass ALL of them too often, but I was hoping to have a function that would read the input data (in this case from a TCP network), and then parse the data (IE, the 3rd byte contains the states of 8 of the digital outputs (according to which bit in that byte is high or low)), and put that into a variable where I can then use elsewhere in the program. I wanted that function to be separate from the main() function, but to do so would require passing pointers to some 20 or so variables that it would be writing to. I know I could make the variables global, but I am trying to make it easier to debug by making it obvious when a function is allowed to edit that variable, by passing it to the function. My best idea was a struct, and just pass a pointer to it, but wasn't sure if there was a more efficient way, especially since there is only really 1 function that would need to access all of them at once, while most others only require parts of the information that will be stored in this bunch of state variables. So anyway, is there a clean way to send many variables between functions at once that need to be edited?

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  • Custom ASP.net UserControl List<T> Property, having trouble setting declaratively

    - by Chris McCall
    I'm developing a custom UserControl to inject JQuery hotkeys into a page declaratively on the server side. Here's the control (the important parts anyway): [AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal), AspNetHostingPermission(SecurityAction.InheritanceDemand, Level = AspNetHostingPermissionLevel.Minimal), DefaultProperty("HotKeys"), ParseChildren(true, "HotKeys"), ToolboxData("<{0}:HotKeysControl runat=\"server\"> </{0}:HotKeysControl>")] public partial class HotKeysControl : System.Web.UI.WebControls.WebControl { private string crlf = Environment.NewLine; public List<HotKey> _HotKeys; public HotKeysControl() { if (_HotKeys == null) { _HotKeys = new List<HotKey>(); } // if I uncomment this line, script is injected into the page // _HotKeys.Add(new HotKey("ctrl+r","thisControl")); } [ Category("Behavior"), Description("The hotkeys collection"), DesignerSerializationVisibility( DesignerSerializationVisibility.Content), Editor(typeof(HotKeyCollectionEditor), typeof(UITypeEditor)), PersistenceMode(PersistenceMode.InnerDefaultProperty) ] public List<HotKey> HotKeys { set { _HotKeys = value; } get { return _HotKeys; } } Here's the .aspx code: <%@ Register Assembly="MyCompany.ProductName.WebControls" Namespace="MyCompany.ProductName.WebControls" TagPrefix="uc" %> ... <uc:HotKeysControl ID="theHotkeys" runat="server" Visible="false"> <uc:HotKey ControlName="firstControl" KeyCode="ctrl+1" /> <uc:HotKey ControlName="thirdControl" KeyCode="ctrl+2" /> </uc:HotKeysControl> Nothing happens, as if no HotKeys objects are being added to the property collection. What Am I doing wrong? If I uncomment out the line above and "manually" add items, it works. It's something about how I'm declaratively adding hotkeys to the page. Any ideas?

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  • Help me find article on Multi-threading and Event Handling in Java

    - by JDR
    I once read an article on how to properly write event handlers for multi-threading in Java, but I can't for the life of me find it anymore. It described the pitfalls and potentials for deadlocks that can occur when firing events (not Swing events mind you, but general events like model update notifications). To clarify, the situation would be as such: // let's say this is code from an MVC model somewhere public void setSomeProperty(String myProperty){ if(!this.myProperty.equals(myProperty)){ this.myProperty = myProperty; fireMyPropertyChangedEvent(...); } } The article described how passing control to arbitrary external listener code was a potential cause for deadlock. I now find myself in a situation where I need to fire such events in a multithreaded environment and I would very much like to read the article again to see what it has to say before I continue. Does anyone know the article I'm referring to? I believe it came as a (fairly short) PDF. It started off with an initial naive implementation and incrementally pointed out flaws and improved upon it. It ended with a sort of final proper-way-to-fire-multithreaded-events. I've searched endlessly in my browse history and on google, but all I could find were endless amounts topics on Swing event dispatch threads. Thank you.

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  • Dropdown not working in some IE 6 browsers

    - by James Thomas
    We unfortunately find ourselves having to support our product in IE 6 because some of our largest users use it. One of them called today and told me that one of the dropdowns doesn't work when he clicks on it - it simply selects the first item. I checked the markup and the entire contents of the select control are being sent: <select onchange="SDateFilter_S('#ctlDateRange')" size="1" name="ctlDateRange" style="width:100px;"> <option selected="selected" value="0"> All Dates </option><option value="1"> Within </option><option value="2"> Before </option><option value="3"> After </option><option value="4"> Between </option><option value="5"> Last </option><option value="6"> Since </option> </select> This is done in ASP .NET but I am fairly certain the issue isn't with ASP .NET as when I try it in my copy of IE 6, it works correctly. Do you have any idea what would cause a dropdown list in some copies of IE 6 to effectively not work?

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  • Subversion unable to merge changes when using Dreamweaver

    - by neilc
    I've got a project running and we're using SVN as the version control. There are 3 devs on it. Dev1 = OSX + Textmate Dev2 = Windows 7 + Dreamweaver (plus tortoise svn) Dev3 = OSX + Coda Case 1 (expected): Dev1 and dev3 work on a file called signup.php. They work on different parts of the file. Dev1 commits it and dev3 updates their copy. signup.php is merged as expected. All good. Case 2 (not expected): Dev1 and dev2 work on a file called signup.php. They work on different parts of the file. Dev1 commits it and dev2 updates their copy. signup.php is always in conflict even though different parts of the file are worked on. This is not the expected behaviour experienced by dev1 and dev3. This works boths ways and each time dev1 updates dev2's changes he gets conflicts too. But never with dev3. Could this be down the way Dreamweaver is saving files ? Perhaps character encoding. We are all working in UTF8. These constant and unnecessary conflicts are becoming a massive distraction. Help !

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  • How to populate the span tags between specific tags.

    - by Rachel
    I want to populate span tags for all text nodes between the self closing tags s1 and s2 having the same id.If the transformation of the input to the output form requires the list of ids of the s1 , s2 tag pairs say 1, 2 etc i can assume that it is in place in any form if required.The input can have any structure and not exactly the same as seen in the sample input. It can have any number of s1, s2 tag pairs but each pair will have a unique id. Hope i am clear. How can this be achieved using XSL? Input: <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>This is my title</title> </head> <body> <h1 align="center">This <s1 id="1" />is my <s2 id="1" />heading</h1> <p> Sample content <s1 id="2" />Some text here. Some content here. </p> <p> Here you <s2 id="2" />go. </p> </body> </html> Desired output: <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>This is my title</title> </head> <body> <h1 align="center">This <span id="1">is my </span>heading</h1> <p> Sample content <span id="2">Some text here. Some content here.</span> </p> <p> <span id="2">Here you </span>go. </p> </body> </html>

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  • Python-based password tracker (or dictionary)

    - by Arrieta
    Hello: Where we work we need to remember about 10 long passwords which need to change every so often. I would like to create a utility which can potentially save these passwords in an encrypted file so that we can keep track of them. I can think of some sort of dictionary passwd = {'host1':'pass1', 'host2':'pass2'}, etc, but I don't know what to do about encryption (absolutely zero experience in the topic). So, my question is really two questions: Is there a Linux-based utility which lets you do that? If you were to program it in Python, how would you go about it? A perk of approach two, would be for the software to update the ssh public keys after the password has been changed (you know the pain of updating ~15 tokens once you change your password). As it can be expected, I have zero control over the actual network configuration and the management of scp keys. I can only hope to provide a simple utility to me an my very few coworkers so that, if we need to, we can retrieve a password on demand. Cheers.

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  • Reason for socket.error

    - by August Flanagan
    Hi, I am a complete newbie when it comes to python, and programming in general. I've been working on a little webapp for the past few weeks trying to improve my coding chops. A few days ago my laptop was stolen so I went out and got a new MacBook Pro. Thank God I had everything under subversion control. The problem is now that I am on my new machine a script that I was running has stopped working and I have no idea why. This is really the only part of what I have been writing that I borrowed heavily for existing scripts. It is from the widely available whois.py script and I have only slightly modified it as follows (see below). It was running fine on my old system (running ubuntu), but now the socket.error is being raised. I'm completely lost on this, and would really appreciate any help. Thanks! def is_available(domainname, whoisserver="whois.verisign-grs.com", cache=0): if whoisserver is None: whoisserver = "whois.networksolutions.com" s = None while s == None: try: s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.setblocking(0) try: s.connect((whoisserver, 43)) except socket.error, (ecode, reason): if ecode in (115, 150): pass else: raise socket.error, (ecode, reason) ret = select.select([s], [s], [], 30) if len(ret[1])== 0 and len(ret[0]) == 0: s.close() raise TimedOut, "on connect " s.setblocking(1) except socket.error, (ecode, reason): print ecode, reason time.sleep(1) s = None s.send("%s \n\n" % domainname) page = "" while 1: data = s.recv(8196) if not data: break page = page + data s.close()

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  • Derived template override return type of member function C++

    - by Ruud v A
    I am writing matrix classes. Take a look at this definition: template <typename T, unsigned int dimension_x, unsigned int dimension_y> class generic_matrix { ... generic_matrix<T, dimension_x - 1, dimension_y - 1> minor(unsigned int x, unsigned int y) const { ... } ... } template <typename T, unsigned int dimension> class generic_square_matrix : public generic_matrix<T, dimension, dimension> { ... generic_square_matrix(const generic_matrix<T, dimension, dimension>& other) { ... } ... void foo(); } The generic_square_matrix class provides additional functions like matrix multiplication. Doing this is no problem: generic_square_matrix<T, 4> m = generic_matrix<T, 4, 4>(); It is possible to assign any square matrix to M, even though the type is not generic_square_matrix, due to the constructor. This is possible because the data does not change across children, only the supported functions. This is also possible: generic_square_matrix<T, 4> m = generic_square_matrix<T, 5>().minor(1,1); Same conversion applies here. But now comes the problem: generic_square_matrix<T, 4>().minor(1,1).foo(); //problem, foo is not in generic_matrix<T, 3, 3> To solve this I would like generic_square_matrix::minor to return a generic_square_matrix instead of a generic_matrix. The only possible way to do this, I think is to use template specialisation. But since a specialisation is basically treated like a separate class, I have to redefine all functions. I cannot call the function of the non-specialised class as you would do with a derived class, so I have to copy the entire function. This is not a very nice generic-programming solution, and a lot of work. C++ almost has a solution for my problem: a virtual function of a derived class, can return a pointer or reference to a different class than the base class returns, if this class is derived from the class that the base class returns. generic_square_matrix is derived from generic_matrix, but the function does not return a pointer nor reference, so this doesn't apply here. Is there a solution to this problem (possibly involving an entirely other structure; my only requirements are that the dimensions are a template parameter and that square matrices can have additional functionality). Thanks in advance, Ruud

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  • Reverse engineering and redistributing code from .NET Framework

    - by ToxicAvenger
    Once or twice I have been running into the following issue: Classes I want to reuse in my applications (and possibly redistribute) exist in the .NET Framework assemblies, but are marked internal or private. So it is impossible to reuse them directly. One way is to disassemble them, pick the pieces you need, put them in a different namespace, recompile (this can be some effort, but usually works quite well). My question is: Is this legal? Is this only legal for the classes of the Framework which are available as source code anyway? Is it illegal? I think that Microsoft marks them internal or private primarily so that they don't have to support them or can change the interfaces later. But some pieces - be it SharePoint or WCF - are almost impossible to properly extend by only using public classes from the apis. And rewriting everything from scratch generates a huge amount of effort, before you even start solving the problem you intended to solve. This is in my eyes not a "dirty" approach per se. The classes Microsoft ships are obviously well tested, if I reuse them under a different namespace I have "control" over them. If Microsoft changes the original implementation, my code won't be affected (some internals in WCF changed quite a bit with v4). It is not a super-clean approach. I would much prefer Microsoft making several classes public, because there are some nice classes hidden inside the framework.

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  • How can I improve my select query for storing large versioned data sets?

    - by Jason Francis
    At work, we build large multi-page web applications, consisting mostly of radio and check boxes. The primary purpose of each application is to gather data, but as users return to a page they have previously visited, we report back to them their previous responses. Worst-case scenario, we might have up to 900 distinct variables and around 1.5 million users. For several reasons, it makes sense to use an insert-only approach to storing the data (as opposed to update-in-place) so that we can capture historical data about repeated interactions with variables. The net result is that we might have several responses per user per variable. Our table to collect the responses looks something like this: CREATE TABLE [dbo].[results]( [id] [bigint] IDENTITY(1,1) NOT NULL, [userid] [int] NULL, [variable] [varchar](8) NULL, [value] [tinyint] NULL, [submitted] [smalldatetime] NULL) Where id serves as the primary key. Virtually every request results in a series of insert statements (one per variable submitted), and then we run a select to produce previous responses for the next page (something like this): SELECT t.id, t.variable, t.value FROM results t WITH (NOLOCK) WHERE t.userid = '2111846' AND (t.variable='internat' OR t.variable='veteran' OR t.variable='athlete') AND t.id IN (SELECT MAX(id) AS id FROM results WITH (NOLOCK) WHERE userid = '2111846' AND (t.variable='internat' OR t.variable='veteran' OR t.variable='athlete') GROUP BY variable) Which, in this case, would return the most recent responses for the variables "internat", "veteran", and "athlete" for user 2111846. We have followed the advice of the database tuning tools in indexing the tables, and against our data, this is the best-performing version of the select query that we have been able to come up with. Even so, there seems to be significant performance degradation as the table approaches 1 million records (and we might have about 150x that). We have a fairly-elegant solution in place for sharding the data across multiple tables which has been working quite well, but I am open for any advice about how I might construct a better version of the select query. We use this structure frequently for storing lots of independent data points, and we like the benefits it provides. So the question is, how can I improve the performance of the select query? I assume the nested select statement is a bad idea, but I have yet to find an alternative that performs as well. Thanks in advance. NB: Since we emphasize creating over reading in this case, and since we never update in place, there doesn't seem to be any penalty (and some advantage) for using the NOLOCK directive in this case.

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