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• Why page_load is called twice in my web application?

  - by harisri786

  Hi, I have already gone through some of the posts in many websites regarding page_load being called twice but my problem is little bit different from those. My problem is with the landing page of my web application. Initially in my website page_load for the landing page was getting called twice every time when it is loaded. Since my application is an upgraded one (from VS 2003 to VS 2005/2008), I commented the "this.load" event in InitializeComponent. Now it works fine, when user first logs in, into my web application. But then, whenever user navigates to this page from any other page in my application, page_load gets called twice. Does anybody have any idea about why this could be happening. I tried to track the call stack for this, but VS 2008 was showing that this was getting called from external code. Also, I am using frames in my web application. I wonder if this problem has anything to do with frames. Any help is deeply appreciated. Regards, Hari

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• WebKit and Opera won't load from this server when it's in a frame

  - by crimson_penguin

  This site loads fine in Firefox, but in WebKit browsers (Safari and Google Chrome) it won't load the frame, and in Opera I get this error: "The Web site does not permit its content to be displayed in a frame. It must be displayed in a separate window.". I don't expect to be able to actually fix this, as I don't have control over the frames page (only the content of the frame), but my question is: why? The content of the frame loads fine by itself, and saving the frames page and changing the src of the frame to http://w3.org/ loads fine. I did a bit of searching based on the Opera error, and it seemed to suggest it had to do with redirecting. That URL does indeed redirect, but if I change it to http://mini.milli.no/tonje/main (which doesn't redirect), it still doesn't work. Even Apache directory listings don't work - which to me suggests it's server related. But how can a server do that? To be total clear, I'm using Mac OS X 10.6.3, and I tested with Safari 4.0.5, Chrome 5.0.375.55, Opera 10.53, and Firefox 3.6.3. Basically, the newest of all of those things currently.

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• Inserting bits into byte

  - by JB_SO

  I was looking at an example of reading bits from a byte and the implementation looked simple and easy to understand. I was wondering if anyone has a similar example of how to insert bits into a byte or byte array, that is easier to understand and also implement like the example below. Here is the example I found of reading bits from a byte (http://bytes.com/topic/c-sharp/answers/505085-reading-bits-byte-file): static int GetBits3(byte b, int offset, int count) { return (b >> offset) & ((1 << count) - 1); } Here is what i'm trying to do....and this is my current implementation.....just a little confused with the bit-masking/shifting, etc, that's why I'm trying to find out if there is an easier way to do what i'm doing BYTE Msg[2]; Msg_Id = 3; Msg_Event = 1; Msg_Ready = 2; Msg[0] = ( ( Msg_Event << 4 ) & 0xF0 ) | ( Msg_Id & 0x0F ) ; Msg[1] = Msg_Ready & 0x0F; //MsgReady & Unused Thanks for your help!

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• Name for method that takes a string value and returns DBNull.Value || string

  - by David Murdoch

  I got tired of writing the following code: /* Commenting out irrelevant parts public string MiddleName; public void Save(){ SqlCommand = new SqlCommand(); // blah blah...boring INSERT statement with params etc go here. */ if(MiddleName==null){ myCmd.Parameters.Add("@MiddleName", DBNull.Value); } else{ myCmd.Parameters.Add("@MiddleName", MiddleName); } /* // more boring code to save to DB. }*/ So, I wrote this: public static object DBNullValueorStringIfNotNull(string value) { object o; if (value == null) { o = DBNull.Value; } else { o = value; } return o; } // which would be called like: myCmd.Parameters.Add("@MiddleName", DBNullValueorStringIfNotNull(MiddleName)); If this is a good way to go about doing this then what would you suggest as the method name? DBNullValueorStringIfNotNull is a bit verbose and confusing. I'm also open to ways to alleviate this problem entirely. I'd LOVE to do this: myCmd.Parameters.Add("@MiddleName", MiddleName==null ? DBNull.Value : MiddleName); but that won't work. I've got C# 3.5 and SQL Server 2005 at my disposal if it matters.

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• Is this a good or bad way to use constructor chaining? (... to allow for testing).

  - by panamack

  My motivation for chaining my class constructors here is so that I have a default constructor for mainstream use by my application and a second that allows me to inject a mock and a stub. It just seems a bit ugly 'new'-ing things in the ":this(...)" call and counter-intuitive calling a parametrized constructor from a default constructor , I wondered what other people would do here? (FYI - SystemWrapper) using SystemWrapper; public class MyDirectoryWorker{ // SystemWrapper interface allows for stub of sealed .Net class. private IDirectoryInfoWrap dirInf; private FileSystemWatcher watcher; public MyDirectoryWorker() : this( new DirectoryInfoWrap(new DirectoryInfo(MyDirPath)), new FileSystemWatcher()) { } public MyDirectoryWorker(IDirectoryInfoWrap dirInf, FileSystemWatcher watcher) { this.dirInf = dirInf; if(!dirInf.Exists){ dirInf.Create(); } this.watcher = watcher; watcher.Path = dirInf.FullName; watcher.NotifyFilter = NotifyFilters.FileName; watcher.Created += new FileSystemEventHandler(watcher_Created); watcher.Deleted += new FileSystemEventHandler(watcher_Deleted); watcher.Renamed += new RenamedEventHandler(watcher_Renamed); watcher.EnableRaisingEvents = true; } public static string MyDirPath{get{return Settings.Default.MyDefaultDirPath;}} // etc... }

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• Please help optimizing a long running query (left outer join, with 2 subqueries)

  - by 46and2

  Hi all. The query I need help with is: SELECT d.bn, d.4700, d.4500, ... , p.`Activity Description` FROM ( SELECT temp.bn, temp.4700, temp.4500, .... FROM `tdata` temp GROUP BY temp.bn HAVING (COUNT(temp.bn) = 1) ) d LEFT OUTER JOIN ( SELECT temp2.bn, max(temp2.FPE) AS max_fpe, temp2.`Activity Description` FROM `pdata` temp2 GROUP BY temp2.bn ) p ON p.bn = d.bn; The ... represents other fields that aren't really important to solving this problem. The issue is on the the second subquery - it is not using the index I have created and I am not sure why, it seems to be because of the way TEXT fields are handled. The first subquery uses the index I have created and runs quite snappy, however an explain on the second shows a 'Using temporary; Using filesort'. Please see the indexes I have created in the below table create statements. Can anyone help me optimize this? By way of quick explanation the first subquery is meant to only select records that have unique bn's, the second, while it looks a bit wacky (with the max function there which is not being used in the result set) is making sure that only one record from the right part of the join is included in the result set. My table create statements are CREATE TABLE `tdata` ( `BN` varchar(15) DEFAULT NULL, `4000` varchar(3) DEFAULT NULL, `5800` varchar(3) DEFAULT NULL, .... KEY `BN` (`BN`), KEY `idx_t3010`(`BN`,`4700`,`4500`,`4510`,`4520`,`4530`,`4570`,`4950`,`5000`,`5010`,`5020`,`5050`,`5060`,`5070`,`5100`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 CREATE TABLE `pdata` ( `BN` varchar(15) DEFAULT NULL, `FPE` datetime DEFAULT NULL, `Activity Description` text, .... KEY `BN` (`BN`), KEY `idx_programs_2009` (`BN`,`FPE`,`Activity Description`(100)) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 Thanks!

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• URL shortening: using inode as short name?

  - by Licky Lindsay

  The site I am working on wants to generate its own shortened URLs rather than rely on a third party like tinyurl or bit.ly. Obviously I could keep a running count new URLs as they are added to the site and use that to generate the short URLs. But I am trying to avoid that if possible since it seems like a lot of work just to make this one thing work. As the things that need short URLs are all real physical files on the webserver my current solution is to use their inode numbers as those are already generated for me ready to use and guaranteed to be unique. function short_name($file) { $ino = @fileinode($file); $s = base_convert($ino, 10, 36); return $s; } This seems to work. Question is, what can I do to make the short URL even shorter? On the system where this is being used, the inodes for newly added files are in a range that makes the function above return a string 7 characters long. Can I safely throw away some (half?) of the bits of the inode? And if so, should it be the high bits or the low bits? I thought of using the crc32 of the filename, but that actually makes my short names longer than using the inode. Would something like this have any risk of collisions? I've been able to get down to single digits by picking the right value of "$referencefile". function short_name($file) { $ino = @fileinode($file); // arbitrarily selected pre-existing file, // as all newer files will have higher inodes $ino = $ino - @fileinode($referencefile); $s = base_convert($ino, 10, 36); return $s; }

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• Large flags enumerations in C#

  - by LorenVS

  Hey everyone, got a quick question that I can't seem to find anything about... I'm working on a project that requires flag enumerations with a large number of flags (up to 40-ish), and I don't really feel like typing in the exact mask for each enumeration value: public enum MyEnumeration : ulong { Flag1 = 1, Flag2 = 2, Flag3 = 4, Flag4 = 8, Flag5 = 16, // ... Flag16 = 65536, Flag17 = 65536 * 2, Flag18 = 65536 * 4, Flag19 = 65536 * 8, // ... Flag32 = 65536 * 65536, Flag33 = 65536 * 65536 * 2 // right about here I start to get really pissed off } Moreover, I'm also hoping that there is an easy(ier) way for me to control the actual arrangement of bits on different endian machines, since these values will eventually be serialized over a network: public enum MyEnumeration : uint { Flag1 = 1, // BIG: 0x00000001, LITTLE:0x01000000 Flag2 = 2, // BIG: 0x00000002, LITTLE:0x02000000 Flag3 = 4, // BIG: 0x00000004, LITTLE:0x03000000 // ... Flag9 = 256, // BIG: 0x00000010, LITTLE:0x10000000 Flag10 = 512, // BIG: 0x00000011, LITTLE:0x11000000 Flag11 = 1024 // BIG: 0x00000012, LITTLE:0x12000000 } So, I'm kind of wondering if there is some cool way I can set my enumerations up like: public enum MyEnumeration : uint { Flag1 = flag(1), // BOTH: 0x80000000 Flag2 = flag(2), // BOTH: 0x40000000 Flag3 = flag(3), // BOTH: 0x20000000 // ... Flag9 = flag(9), // BOTH: 0x00800000 } What I've Tried: // this won't work because Math.Pow returns double // and because C# requires constants for enum values public enum MyEnumeration : uint { Flag1 = Math.Pow(2, 0), Flag2 = Math.Pow(2, 1) } // this won't work because C# requires constants for enum values public enum MyEnumeration : uint { Flag1 = Masks.MyCustomerBitmaskGeneratingFunction(0) } // this is my best solution so far, but is definitely // quite clunkie public struct EnumWrapper<TEnum> where TEnum { private BitVector32 vector; public bool this[TEnum index] { // returns whether the index-th bit is set in vector } // all sorts of overriding using TEnum as args } Just wondering if anyone has any cool ideas, thanks!

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• UITableView with dynamic cell heights -- what do I need to do to fix scrolling down?

  - by Ian Terrell

  I am building a teensy tiny little Twitter client on the iPhone. Naturally, I'm displaying the tweets in a UITableView, and they are of course of varying lengths. I'm dynamically changing the height of the cell based on the text quite fine: - (CGFloat)heightForTweetCellWithString:(NSString *)text { CGFloat height = Buffer + [text sizeWithFont:Font constrainedToSize:Size lineBreakMode:LineBreakMode].height; return MAX(height, MinHeight); } - (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath { NSString *text = // get tweet text for this indexpath return [self heightForTweetCellWithString:text]; } } I'm displaying the actual tweet cell using the algorithm in the PragProg book: - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *CellIdentifier = @"TweetCell"; TweetCell *cell = (TweetCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (cell == nil) { cell = [self createNewTweetCellFromNib]; } cell.tweet.text = // tweet text // set other labels, etc return cell; } When I boot up, all the tweets visible display just fine. However, when I scroll down, the tweets below are quite mussed up -- it appears that once a cell has scrolled off the screen, the cell height for the one above it gets resized to be larger than it should be, and obscures part of the cell below it. When the cell reaches the top of the view, it resets itself and renders properly. Scrolling up presents no difficulties. Here is a video that shows this in action: http://screencast.com/t/rqwD9tpdltd I've tried quite a bit already: resizing the cell's frame on creation, using different identifiers for cells with different heights (i.e. [NSString stringWithFormat:@"Identifier%d", rowHeight]), changing properties in Interface Builder... If there are additional code snippets I can post, please let me know. Thanks in advance for your help!

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• implement SIMD in C++

  - by Hristo

  I'm working on a bit of code and I'm trying to optimize it as much as possible, basically get it running under a certain time limit. The following makes the call... static affinity_partitioner ap; parallel_for(blocked_range<size_t>(0, T), LoopBody(score), ap); ... and the following is what is executed. void operator()(const blocked_range<size_t> &r) const { int temp; int i; int j; size_t k; size_t begin = r.begin(); size_t end = r.end(); for(k = begin; k != end; ++k) { // for each trainee temp = 0; for(i = 0; i < N; ++i) { // for each sample int trr = trRating[k][i]; int ei = E[i]; for(j = 0; j < ei; ++j) { // for each expert temp += delta(i, trr, exRating[j][i]); } } myscore[k] = temp; } } I'm using Intel's TBB to optimize this. But I've also been reading about SIMD and SSE2 and things along that nature. So my question is, how do I store the variables (i,j,k) in registers so that they can be accessed faster by the CPU? I think the answer has to do with implementing SSE2 or some variation of it, but I have no idea how to do that. Any ideas? Thanks, Hristo

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• Cannot run Python script on Windows with output redirected??

  - by Wai Yip Tung

  This is running on Windows 7 (64 bit), Python 2.6 with Win32 Extensions for Python. I have a simple script that just print "hello world". I can launch it with python hello.py. In this case I can redirect the output to a file. But if I run it by just typing hello.py on the command line and redirect the output, I get an exception. C:> python hello.py hello world C:> python hello.py >output C:> type output hello world C:> hello.py hello world C:> hello.py >output close failed in file object destructor: Error in sys.excepthook: Original exception was: I think I first get this error after upgrading to Windows 7. I remember it should work in XP. I have seen people talking about this bug python-Bugs-1012692 | Can't pipe input to a python program. But that was long time ago. And it does not mention any solution. Have anyone experienced this? Anyone can help?

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• PHP Preg_replace after a specific amount of characters with a conditional

  - by Marc Ripley

  I've been working on this for a bit, but my regex is weak. I need to check to see if a number is a whole number (single digit) and append a ".001" to it if so. The problem is, it's in the middle of a line with values separated by commas. MATERIALS,1,1,9999;1 4PL1 PB_Mel,,1,6,0.173,0.173,0.375,0,0.375,0,0,0,0,2,0,1,1 Needs to be MATERIALS,1,1,9999;1 4PL1 PB_Mel,,1.001,6,0.173,0.173,0.375,0,0.375,0,0,0,0,2,0,1,1 The line must start with "MATERIALS". There are more than one MATERIALS lines. The value will always be after 5 commas. I was trying something like this to even replace the number, but I don't think the approach is quite right: $stripped = preg_replace('/(MATERIALS)(,.*?){4}(,\d+?),/', '\2,', $stripped); I tried going through a preg_match_all for if process, to at least get the conditional working, but I still have to replace the lines. for($i=0;$i<sizeof($materialsLines[0]);$i++) { $section = explode(",",$materialsLines[0][$i]); if (strlen($section[5]) == 1) { $section[5] .= ".001"; } $materialsLines[0][$i] = implode(",",$section); }

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• How does the socket API accept() function work?

  - by Eli Bendersky

  The socket API is the de-facto standard for TCP/IP and UDP/IP communications (that is, networking code as we know it). However, one of its core functions, accept() is a bit magical. To borrow a semi-formal definition: accept() is used on the server side. It accepts a received incoming attempt to create a new TCP connection from the remote client, and creates a new socket associated with the socket address pair of this connection. In other words, accept returns a new socket through which the server can communicate with the newly connected client. The old socket (on which accept was called) stays open, on the same port, listening for new connections. How does accept work? How is it implemented? There's a lot of confusion on this topic. Many people claim accept opens a new port and you communicate with the client through it. But this obviously isn't true, as no new port is opened. You actually can communicate through the same port with different clients, but how? When several threads call recv on the same port, how does the data know where to go? I guess it's something along the lines of the client's address being associated with a socket descriptor, and whenever data comes through recv it's routed to the correct socket, but I'm not sure. It'd be great to get a thorough explanation of the inner-workings of this mechanism.

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• why am I stuck on "Initiating update" when deploying to google

  - by michelle

  I've have not had any trouble deploying through eclipse until now. I'm guessing it might have to do with all the stuff I've added today a folder of .pdf and .tex files (in war/web-inf directory) a bit of JDO stuff and a servlet that reads the files in the directory and indexes them into the JDO Is there any way to find out what exactly is the problem? I currently get stuck at "Initiating update" and the stack trace say "ConnectionReset" Any helkp of imput will be appreciated, I really need to deploy this today, thanks! here's the deploy trace: Unable to update: java.net.SocketException: Connection reset at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source) at java.lang.reflect.Constructor.newInstance(Unknown Source) at sun.net.www.protocol.http.HttpURLConnection$6.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at sun.net.www.protocol.http.HttpURLConnection.getChainedException(Unknown Source) at sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown Source) at java.net.HttpURLConnection.getResponseCode(Unknown Source) at com.google.appengine.tools.admin.ServerConnection.getAuthCookie(ServerConnection.java:315) at com.google.appengine.tools.admin.ServerConnection.authenticate(ServerConnection.java:219) at com.google.appengine.tools.admin.ServerConnection.send(ServerConnection.java:145) at com.google.appengine.tools.admin.ServerConnection.post(ServerConnection.java:81) at com.google.appengine.tools.admin.AppVersionUpload.send(AppVersionUpload.java:427) at com.google.appengine.tools.admin.AppVersionUpload.beginTransaction(AppVersionUpload.java:241) at com.google.appengine.tools.admin.AppVersionUpload.doUpload(AppVersionUpload.java:98) at com.google.appengine.tools.admin.AppAdminImpl.update(AppAdminImpl.java:56) at com.google.appengine.eclipse.core.proxy.AppEngineBridgeImpl.deploy(AppEngineBridgeImpl.java:271) at com.google.appengine.eclipse.core.deploy.DeployProjectJob.runInWorkspace(DeployProjectJob.java:148) at org.eclipse.core.internal.resources.InternalWorkspaceJob.run(InternalWorkspaceJob.java:38) at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55) Caused by: java.net.SocketException: Connection reset at java.net.SocketInputStream.read(Unknown Source) at java.io.BufferedInputStream.fill(Unknown Source) at java.io.BufferedInputStream.read1(Unknown Source) at java.io.BufferedInputStream.read(Unknown Source) at sun.net.www.http.HttpClient.parseHTTPHeader(Unknown Source) at sun.net.www.http.HttpClient.parseHTTP(Unknown Source) at sun.net.www.http.HttpClient.parseHTTP(Unknown Source) at sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown Source) at sun.net.www.protocol.http.HttpURLConnection.getHeaderFieldKey(Unknown Source) at com.google.appengine.tools.util.ClientCookieManager.readCookies(ClientCookieManager.java:123) at com.google.appengine.tools.admin.ServerConnection.connect(ServerConnection.java:340) at com.google.appengine.tools.admin.ServerConnection.getAuthCookie(ServerConnection.java:314) ... 11 more

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• Use Zip to Pre-Populate City/State Form with jQuery AJAX

  - by Paul

  I'm running into a problem that I can solve fine by just submitting a form and calling a db to retrieve/echo the information, but AJAX seems to be a bit different for doing this (and is what I need). Earlier in a form process I ask for the zip code like so: <input type="text" maxlength="5" size="5" id="zip" /> Then I have a button to continue, but this button just runs a javascript function that shows the rest of the form. When the rest of the form shows, I want to pre-populate the City input with their city, and pre-populate the State dropdown with their state. I figured I would have to find a way to set city/state to variables, and echo the variables into the form. But I can't figure out how to get/set those variables with AJAX as opposed to a form submit. Here's how I did it without ajax: $zip = mysql_real_escape_string($_POST['zip']); $q = " SELECT city FROM citystatezip WHERE zip = $zip"; $r = mysql_query($q); $row = mysql_fetch_assoc($r); $city = $row['city']; Can anybody help me out with using AJAX to set these variables? Thanks!

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• Diagnosing IIS Shutdowns

  - by Tom Ritter

  Symptoms: I attach a debugger, I wait a little while, it automatically detaches I watch the event log during normal operation - after a single request comes in, it waits a little bit, the shuts down Disagnosing. I've followed the following steps for logging shutdowns in IIS: http://weblogs.asp.net/scottgu/archive/2005/12/14/433194.aspx http://blogs.msdn.com/tess/archive/2006/08/02/asp-net-case-study-lost-session-variables-and-appdomain-recycles.aspx I know these are working because... What I see in the Event Logs when I change the web.config: The description for Event ID 0 from source ASP.NET 2.0.50727.0 cannot be found. Either the component that raises this event is not installed on your local computer or the installation is corrupted. You can install or repair the component on the local computer. If the event originated on another computer, the display information had to be saved with the event. The following information was included with the event: _shutdownMessage=IIS configuration change HostingEnvironment initiated shutdown CONFIG change CONFIG change HostingEnvironment caused shutdown _shutdownStack= at System.Environment.GetStackTrace(Exception e, Boolean needFileInfo) at System.Environment.get_StackTrace() at System.Web.Hosting.HostingEnvironment.InitiateShutdownInternal() at System.Web.Hosting.HostingEnvironment.InitiateShutdown() at System.Web.Hosting.PipelineRuntime.StopProcessing() the message resource is present but the message is not found in the string/message table But it doesn't help because the mysetery error doesn't tell me anything. I see the same thing as from before I added this extra logging: The description for Event ID 0 from source ASP.NET 2.0.50727.0 cannot be found. Either the component that raises this event is not installed on your local computer or the installation is corrupted. You can install or repair the component on the local computer. If the event originated on another computer, the display information had to be saved with the event. The following information was included with the event: _shutdownMessage=HostingEnvironment initiated shutdown HostingEnvironment caused shutdown _shutdownStack= at System.Environment.GetStackTrace(Exception e, Boolean needFileInfo) at System.Environment.get_StackTrace() at System.Web.Hosting.HostingEnvironment.InitiateShutdownInternal() at System.Web.Hosting.HostingEnvironment.InitiateShutdown() at System.Web.Hosting.PipelineRuntime.StopProcessing() the message resource is present but the message is not found in the string/message table Anyone have any ideas for more debugging?

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• Developing on both Windows & Linux machines simultaneously

  - by Jamie

  Sorry for the bad title (couldn't think of a better way to describe it) I have a windows machine which I do development on. However, I have a new project which needs to interact with a linux system (executing linux commands etc.). So, obviously I can't do development on my windows machine..and I don't wish to code on the dev machine, svn commit and then svn update it on the linux machine. Is there a way where any changes I make on my dev machine will be quickly mirrored to the linux machine? SVN is not a very quick alternative and of course some changes will be very minor. Any ideas? A network share I guess....but that's not very pretty (bit slow too). As fellow developers I would like to know if you've been in a similar situation and how you've resolved it. On a furthernote, I can't just install Ubuntu as my development machine and mirror the commands, applications etc. from the linux machine because it's a cluster 'master' machine and so therefore it has quite a special configuration. Thanks guys! EDIT: I've also thought about having web services on the linux machine and then just calling them from code thus seperating platform development dependency. What do you think about that too? thanks

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• iPhone: Leak with UIWebView loading Office documents. Any ideas how to avoid it?

  - by Thomas Tempelmann

  While there are already quite a few posts about leaks around UIWebView, mine is a bit more special, I believe, and thus deserves its own post here. I see a reproducible large leak every time I load a Office document such as a Word or Excel file. For instance, every time I display a 180KB .doc file, I get a 100KB leak. And that happens with both the simulator and an actual device, running OS 3.1.3. The leak is not visible with the Leaks instrument but only by looking at the malloc instances via the ObjectAlloc instrument. Here's a picture from the instruments trace: I've also made a demo project, UIWebView-Leak.zip, so you can verify this yourself. To see the leak, use the ObjectAlloc instrument, switch to the view where you see individual allocation objects, and sort by size so that you see the large ones in a group, just like in my picture above. Then view a Office document a few times and find the Malloc objects that keep staying "Live" even after the actual UIWebView has been freed. Is this a known bug? Or is there any way I can avoid these leaks? I.e, have you successfully shown Office documents on an iPhone withing getting such leaks? Note: I've reported this as a bug to Apple now, too (ID 7950594) I am still waiting for someone (including Apple) to confirm this as a true leak or show why it isn't (i.e. that I do something wrong or make wrong assumptions)

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• asyncore callbacks launching threads... ok to do?

  - by sbartell

  I'm unfamiliar with asyncore, and have very limited knowledge of asynchronous programming except for a few intro to twisted tutorials. I am most familiar with threads and use them in all my apps. One particular app uses a couchdb database as its interface. This involves longpolling the db looking for changes and updates. The module I use for couchdb is couchdbkit. It uses an asyncore loop to watch for these changes and send them to a callback. So, I figure from this callback is where I launch my worker threads. It seems a bit crude to mix asynchronous and threaded programming. I really like couchdbkit, but would rather not introduce issues into my program. So, my question is, is it safe to fire threads from an async callback? Here's some code... {{{ def dispatch(change): global jobs, db_url # jobs is my queue db = Database(db_url) work_order = db.get(change['id']) # change is an id to the document that changed. # i need to get the actual document (workorder) worker = Worker(work_order, db) # fire the thread jobs.append[worker] worker.start() return main() . . . consumer.wait(cb=dispatch, since=update_seq, timeout=10000) #wait constains the asyncloop. }}}

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• Having Issue with Bounded Wildcards in Generic

  - by Sanjiv

  I am new to Java Generics, and I'm currently experimenting with Generic Coding....final goal is to convert old Non-Generic legacy code to generic one... I have defined two Classes with IS-A i.e. one is sub-class of other. public class Parent { private String name; public Parent(String name) { super(); this.name = name; } } public class Child extends Parent{ private String address; public Child(String name, String address) { super(name); this.address = address; } } Now, I am trying to create a list with bounded Wildcard. and getting Compiler Error. List<? extends Parent> myList = new ArrayList<Child>(); myList.add(new Parent("name")); // compiler-error myList.add(new Child("name", "address")); // compiler-error myList.add(new Child("name", "address")); // compiler-error Bit confused. please help me on whats wrong with this ?

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• Persistant Http client connections in java

  - by Akusete

  I am trying to write a simple Http client application in Java and am a bit confused by the seemingly different ways to establish Http client connections, and efficiently re-use the objects. Current I am using the following steps (I have left out exception handling for simplicity) Iterator<URI> uriIterator = someURIs(); HttpClient client = new DefaultHttpClient(); while (uriIterator.hasNext()) { URI uri = uriIterator.next(); HttpGet request = new HttpGet(uri); HttpResponse response = client.execute(request); HttpEntity entity = response.getEntity(); InputStream s = entity.getContent(); processStream (); s.close(); } In regard to the code above, my questions is: Assuming all URI's are pointing to the same host (but different resources on that host). What is the recommended way to use a single http connection for all requests? And how do you close the connection after the last request? --edit: Also what is the difference between using uri.openConnection(), versus HttpClient? Which is preferable, and what other methods exist?

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• problem with evolutionary algorithms degrading into simulated annealing: mutation too small?

  - by Schnalle

  i have a problem understanding evolutionary algorithms. i tried using this technique several times, but i always ran into the same problem: degeneration into simulated annealing. lets say my initial population, with fitness in brackets, is: A (7), B (9), C (14), D (19) after mating and mutation i have following children: AB (8.3), AC (12.2), AD (14.1), BC(11), BD (14.7), CD (17) after elimination of the weakest, we get A, AB, B, AC next turn, AB will mate again with a result around 8, pushing AC out. next turn, AB again, pushing B out (assuming mutation changes fitness mostly in the 1 range). now, after only a few turns the pool is populated with the originally fittest candidates (A, B) and mutations of those two (AB). this happens regardless of the size of the initial pool, it just takes a bit longer. say, with an initial population of 50 it takes 50 turns, then all others are eliminated, turning the whole setup in a more complicated simulated annealing. in the beginning i also mated canditates with themselves, worsening the problem. so, what do i miss? are my mutation rates simply too small and will it go away if i increase them? here's the project i'm using it for: http://stefan.schallerl.com/simuan-grid-grad/ yeah, the code is buggy and the interface sucks, but i'm too lazy to fix it right now - and be careful, it may lock up your browser. better use chrome, even thought firefox is not slower than chrome for once (probably the tracing for the image comparison pays off, yay!). if anyone is interested, the code can be found here. here i just dropped the ev-alg idea and went for simulated annealing. ps: i'm not even sure about simulated annealing - it is like evolutionary algorithms, just with a population size of one, right?

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• Project Euler problem 214, How can i make it more efficient?

  - by Once

  I am becoming more and more addicted to the Project Euler problems. However since one week I am stuck with the #214. Here is a short version of the problem: PHI() is Euler's totient function, i.e. for any given integer n, PHI(n)=numbers of k<=n for which gcd(k,n)=1. We can iterate PHI() to create a chain. For example starting from 18: PHI(18)=6 = PHI(6)=2 = PHI(2)=1. So starting from 18 we get a chain of length 4 (18,6,2,1) The problem is to calculate the sum of all primes less than 40e6 which generate a chain of length 25. I built a function that calculates the chain length of any number and I tested it for small values: it works well and fast. sum of all primes<=20 which generate a chain of length 4: 12 sum of all primes<=1000 which generate a chain of length 10: 39383 Unfortunately my algorithm doesn't scale well. When I apply it to the problem, it takes several hours to calculate... so I stop it because the Project Euler problems must be solved in less than one minute. I thought that my prime detection function might be slow so I fed the program with a list of primes <40e6 to avoid the primality test... The code runs now a little bit faster, but there is still no way to get a solution in less than a few hours (and I don't want this). So is there any "magic trick" that I am missing here ? I really don't understand how to be more efficient on this one... I am not asking for the solution, because fighting with optimization is all the fun of Project Euler. However, any small hint that could put me on the right track would be welcome. Thanks !

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• Can I detect whether an object has called GC.SuppressFinalize?

  - by Joe White

  Is there a way to detect whether or not an object has called GC.SuppressFinalize? I have an object that looks something like this (full-blown Dispose pattern elided for clarity): public class ResourceWrapper { private readonly bool _ownsResource; private readonly UnmanagedResource _resource; public ResourceWrapper(UnmanagedResource resource, bool ownsResource) { _resource = resource; _ownsResource = ownsResource; if (!ownsResource) GC.SuppressFinalize(this); } ~ResourceWrapper() { if (_ownsResource) // clean up the unmanaged resource } } If the ownsResource constructor parameter is false, then the finalizer will have nothing to do -- so it seems reasonable (if a bit quirky) to call GC.SuppressFinalize right from the constructor. However, because this behavior is quirky, I'm very tempted to note it in an XML doc comment... and if I'm tempted to comment it, then I ought to write a unit test for it. But while System.GC has methods to set an object's finalizability (SuppressFinalize, ReRegisterForFinalize), I don't see any methods to get an object's finalizability. Is there any way to query whether GC.SuppressFinalize has been called on a given instance, short of buying Typemock or writing my own CLR host?

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• How can I optimize retrieving lowest edit distance from a large table in SQL?

  - by Matt

  Hey, I'm having troubles optimizing this Levenshtein Distance calculation I'm doing. I need to do the following: Get the record with the minimum distance for the source string as well as a trimmed version of the source string Pick the record with the minimum distance If the min distances are equal (original vs trimmed), choose the trimmed one with the lowest distance If there are still multiple records that fall under the above two categories, pick the one with the highest frequency Here's my working version: DECLARE @Results TABLE ( ID int, [Name] nvarchar(200), Distance int, Frequency int, Trimmed bit ) INSERT INTO @Results SELECT ID, [Name], (dbo.Levenshtein(@Source, [Name])) As Distance, Frequency, 'False' As Trimmed FROM MyTable INSERT INTO @Results SELECT ID, [Name], (dbo.Levenshtein(@SourceTrimmed, [Name])) As Distance, Frequency, 'True' As Trimmed FROM MyTable SET @ResultID = (SELECT TOP 1 ID FROM @Results ORDER BY Distance, Trimmed, Frequency) SET @Result = (SELECT TOP 1 [Name] FROM @Results ORDER BY Distance, Trimmed, Frequency) SET @ResultDist = (SELECT TOP 1 Distance FROM @Results ORDER BY Distance, Trimmed, Frequency) SET @ResultTrimmed = (SELECT TOP 1 Trimmed FROM @Results ORDER BY Distance, Trimmed, Frequency) I believe what I need to do here is to.. Not dumb the results to a temporary table Do only 1 select from `MyTable` Setting the results right in the select from the initial select statement. (Since select will set variables and you can set multiple variables in one select statement) I know there has to be a good implementation to this but I can't figure it out... this is as far as I got: SELECT top 1 @ResultID = ID, @Result = [Name], (dbo.Levenshtein(@Source, [Name])) As distOrig, (dbo.Levenshtein(@SourceTrimmed, [Name])) As distTrimmed, Frequency FROM MyTable WHERE /* ... yeah I'm lost */ ORDER BY distOrig, distTrimmed, Frequency Any ideas?

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