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  • IOS - Performance Issues with SVProgressHUD

    - by ScottOBot
    I have a section of code that is producing pour performance and not working as expected. it utilizes the SVProgressHUD from the following github repository at https://github.com/samvermette/SVProgressHUD. I have an area of code where I need to use [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error]. I want to have a progress hud displayed before the synchronous request and then dismissed after the request has finished. Here is the code in question: //Display the progress HUB [SVProgressHUD showWithStatus:@"Signing Up..." maskType:SVProgressHUDMaskTypeClear]; NSError* error; NSURLResponse *response = nil; [self setUserCredentials]; // create json object for a users session NSDictionary* session = [NSDictionary dictionaryWithObjectsAndKeys: firstName, @"first_name", lastName, @"last_name", email, @"email", password, @"password", nil]; NSData *jsonSession = [NSJSONSerialization dataWithJSONObject:session options:NSJSONWritingPrettyPrinted error:&error]; NSString *url = [NSString stringWithFormat:@"%@api/v1/users.json", CoffeeURL]; NSURL *URL = [NSURL URLWithString:url]; NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:URL cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:30.0]; [request setHTTPMethod:@"POST"]; [request setValue:@"application/json" forHTTPHeaderField:@"Accept"]; [request setValue:@"application/json" forHTTPHeaderField:@"Content-Type"]; [request setValue:[NSString stringWithFormat:@"%d", [jsonSession length]] forHTTPHeaderField:@"Content-Length"]; [request setHTTPBody:jsonSession]; NSData *data = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error]; NSString *dataString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]; NSDictionary *JSONResponse = [NSJSONSerialization JSONObjectWithData:[dataString dataUsingEncoding:NSUTF8StringEncoding] options:NSJSONReadingMutableContainers error:&error]; NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *)response; NSInteger statusCode = httpResponse.statusCode; NSLog(@"Status: %d", statusCode); if (JSONResponse != nil && statusCode == 200) { //Dismiss progress HUB here [SVProgressHUD dismiss]; return YES; } else { [SVProgressHUD dismiss]; return NO; } For some reason the synchronous request blocks the HUB from being displayed. It displays immediately after the synchronous request happens, unfortunatly this is also when it is dismissed. The behaviour displayed to the user is that the app hangs, waits for the synchronous request to finish, quickly flashes the HUB and then becomes responsive again. How can I fix this issue? I want the SVProgressHUB to be displayed during this hang time, how can I do this?

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  • NHibernate, transactions and TransactionScope

    - by Erik
    I'm trying to find the best solution to handle transaction in a web application that uses NHibernate. We use a IHttpModule and at HttpApplication.BeginRequest we open a new session and we bind it to the HttpContext with ManagedWebSessionContext.Bind(context, session); We close and unbind the session on HttpApplication.EndRequest. In our Repository base class, we always wrapped a transaction around our SaveOrUpdate, Delete, Get methods like, according to best practice: public virtual void Save(T entity) { var session = DependencyManager.Resolve<ISession>(); using (var transaction = session.BeginTransaction()) { session.SaveOrUpdate(entity); transaction.Commit(); } } But then this doesn't work, if you need to put a transaction somewhere in e.g. a Application service to include several repository calls to Save, Delete, etc.. So what we tried is to use TransactionScope (I didn't want to write my own transactionmanager). To test that this worked, I use an outer TransactionScope that doesn't call .Complete() to force a rollback: Repository Save(): public virtual void Save(T entity) { using (TransactionScope scope = new TransactionScope()) { var session = Depe.ndencyManager.Resolve<ISession>(); session.SaveOrUpdate(entity); scope.Complete(); } } The block that uses the repository: TestEntity testEntity = new TestEntity { Text = "Test1" }; ITestRepository testRepository = DependencyManager.Resolve<ITestRepository>(); testRepository.Save(testEntity); using (var scope = new TransactionScope()) { TestEntity entityToChange = testRepository.GetById(testEntity.Id); entityToChange.Text = "TestChanged"; testRepository.Save(entityToChange); } TestEntity entityChanged = testRepository.GetById(testEntity.Id); Assert.That(entityChanged.Text, Is.EqualTo("Test1")); This doesn't work. But to me if NHibernate supports TransactionScope it would! What happens is that there is no ROLLBACK at all in the database but when the testRepository.GetById(testEntity.Id); statement is executed a UPDATE with SET Text = "TestCahgned" is fired instead (It should have been fired between BEGIN TRAN and ROLLBACK TRAN). NHibernate reads the value from the level1 cache and fires a UPDATE to the database. Not expected behaviour!? From what I understand whenever a rollback is done in the scope of NHibernate you also need to close and unbind the current session. My question is: Does anyone know of a good way to do this using TransactionScope and ManagedWebSessionContext?

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  • ISQLQuery using AddJoin not loading related instance

    - by Remi Despres-Smyth
    I've got a problem using an ISQLQuery with an AddJoin. The entity I'm trying to return is RegionalFees, which has a composite-id which includes a Province instance. (This is the the instance being improperly loaded.) Here's the mapping: <class name="Project.RegionalFees, Project" table="tblRegionalFees"> <composite-id name="Id" class="Project.RegionalFeesId, project" unsaved-value="any" access="property"> <key-many-to-one class="Project.Province, Project" name="Region" access="property" column="provinceId" not-found="exception" /> <key-property name="StartDate" access="property" column="startDate" type="DateTime" /> </composite-id> <property name="SomeFee" column="someFee" type="Decimal" /> <property name="SomeOtherFee" column="someOtherFee" type="Decimal" /> <!-- Other unrelated stuff --> </class> <class name="Project.Province, Project" table="trefProvince" mutable="false"> <id name="Id" column="provinceId" type="Int64" unsaved-value="0"> <generator class="identity" /> </id> <property name="Code" column="code" access="nosetter.pascalcase-m-underscore" /> <property name="Label" column="label" access="nosetter.pascalcase-m-underscore" /> </class> Here's my query method: public IEnumerable<RegionalFees> GetRegionalFees() { // Using an ISQLQuery cause there doesn't appear to be an equivalent of // the SQL HAVING clause, which would be optimal for loading this set const String qryStr = "SELECT * " + "FROM tblRegionalFees INNER JOIN trefProvince " + "ON tblRegionalFees.provinceId=trefProvince.provinceId " + "WHERE EXISTS ( " + "SELECT provinceId, MAX(startDate) AS MostRecentFeesDate " + "FROM tblRegionalFees InnerRF " + "WHERE tblRegionalFees.provinceId=InnerRF.provinceId " + "AND startDate <= ? " + "GROUP BY provinceId " + "HAVING tblRegionalFees.startDate=MAX(startDate))"; var qry = NHibernateSessionManager.Instance.GetSession().CreateSQLQuery(qryStr); qry.SetDateTime(0, DateTime.Now); qry.AddEntity("RegFees", typeof(RegionalFees)); qry.AddJoin("Region", "RegFees.Id.Region"); return qry.List<RegionalFees>(); } The odd behavior here is that when I call GetRegionalFees (whose goal is to load just the most recent fee instances per region), it all loads fine if the Province instance is a proxy. If, however, Province is not loaded as a transparent proxy, the Province instance which is part of RegionalFees' RegionalFeesId property has null Code and Region values, although the Id value is set correctly. It looks to me like I have a problem in how I'm joining the Province class - since if it's lazy loaded the id is set from tblRegionalFees, and it gets loaded independently afterwards - but I haven't been able to figure out the solution.

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  • When is it worth using a BindingSource?

    - by Justin
    I think I understand well enough what the BindingSource class does - i.e. provide a layer of indirection between a data source and a UI control. It implements the IBindingList interface and therefore also provides support for sorting. And I've used it frequently enough, without too many problems. But I'm wondering if I use it more often than I should. Perhaps an example would help. Let's say I have just a simple textbox on a form (using WinForms), and I'd like to bind that textbox to a simple property inside a class that returns a string. Is it worth using a BindingSource in this situation? Now let's say I have a grid on my form, and I'd like to bind it to a DataTable. Should I use a BindingSource now? In the latter case, I probably would not use a BindingSource, as a DataTable, from what I can gather, provides the same functionality that the BindingSource itself would. The DataTable will fire the the right events when a row is added, deleted, etc so that the grid will automatically update. But in the first case with the textbox being bound to a string, I would probably have the class that contains the string property implement INotifyPropertyChanged, so that it could fire the PropertyChanged event when the string changes. I would use a BindingSource so that it could listen to these PropertyChanged events so that it could update the textbox automatically when the string changes. How does this sound so far? I still feel like there's a gap in my understanding that's preventing me from seeing the whole picture. This has been a pretty vague question so far, so I'll try to ask some more specific questions - ideally the answers will reference the above examples or something similar... (1) Is it worth using a BindingSource in either of the above examples? (2) It seems that developers just "assume" that the DataTable class will do the right thing, in firing PropertyChanged events at the right time. How does one know if a data source is capable of doing this? Is there a particular interface that a data source should implement in order for developers to be able to assume this behaviour? (3) Does it matter what Control is being bound to, when considering whether or not to use a BindingSource? Or is it only the data source that should affect the decision? Perhaps the answer is (and this would seem logical enough): the Control needs to be intelligent enough to listen to the PropertyChanged events, otherwise a BindingSource is required. So how does one tell if the Control is capable of doing this? Again, is there a particular interface that developers can look for that the Control must implement? It is this confusion that has, in the past, led to me always using a BindingSource. But I'd like to understand better exactly when to use one, so that I do so only when necessary.

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  • Using FluentNHibernate + SQLite with .Net4?

    - by stiank81
    I have a WPF application running with .Net3.5 using FluentNHibernate, and all works fine. When I upgraded to VS2010 I ran into some odd problems, but after changing to use x64 variant of SQLite it worked fine again. Now I want to change to use .Net4, but this has turned into a more painful experience then I expected.. When calling FluentConfiguration.BuildConfiguration I get an exception thrown: FluentConfigurationException unhandled An invalid or incomplete configuration was used while creating a SessionFactory. Check PotentialReasons collection, and InnerException for more detail The inner exception gives us more information: Message = "Could not create the driver from NHibernate.Driver.SQLite20Driver, NHibernate, Version=2.1.2.4000, Culture=neutral, PublicKeyToken=aa95f207798dfdb4." It has an InnerException again: Exception has been thrown by the target of an invocation. Which again has an InnerException: The IDbCommand and IDbConnection implementation in the assembly System.Data.SQLite could not be found. Ensure that the assembly System.Data.SQLite is located in the application directory or in the Global Assembly Cache. If the assembly is in the GAC, use element in the application configuration file to specify the full name of the assembly. Now - to me it sounds like it doesn't find System.Data.SQLite.dll, but I can't understand this. Everywhere this is referenced I have "Copy Local", and I have verified that it is in every build folder for projects using SQLite. I have also copied it manually to every Debug folder of the solution - without luck. Notes: This exact same code worked just fine before I upgraded to .Net4. I did see some x64 x86 mismatch problems earlier, but I have switched to use x86 as the target platform and for all referenced dlls. I have verified that all files in the Debug-folder are x86. I have tried the precompiled Fluent dlls, I have tried compiling myself, and I have compiled my own version of Fluent using .Net4. I see that there are also others that have seen this problem, but I haven't really seen any solution yet. After @devio's answer I tried adding a reference to the SQLite dll. This didn't change anything, but I hope I made it right though.. This is what I added to the root node of the app.config file: <runtime> <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1"> <qualifyAssembly partialName="System.Data.SQLite" fullName="System.Data.SQLite, Version=1.0.60.0, Culture=neutral, PublicKeyToken=db937bc2d44ff139" /> </assemblyBinding> </runtime> Anyone out there using Fluent with .Net4 and SQLite successfully? Help! I'm lost...

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  • c# Uploading files to ftp server

    - by etarvt
    Hi there, I have a problem with uploading files to ftp server. I have a few buttons. Every button uploads different files to the ftp. The first time when a button is clicked the file is uploaded successfully, but the second and later tries fail. It gives me "The operation has timed out". When I close the site and then open it again I can upload again only one file. I am sure that I can override files on the ftp. Here's the code: protected void btn_export_OnClick(object sender, EventArgs e) { Stream stream = new MemoryStream(); stream.Position = 0; // fill the stream bool res = this.UploadFile(stream, "test.csv", "dir"); stream.Close(); } private bool UploadFile(Stream stream, string filename, string ftp_dir) { stream.Seek(0, SeekOrigin.Begin); string uri = String.Format("ftp://{0}/{1}/{2}", "host", ftp_dir, filename); try { FtpWebRequest reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri(uri)); reqFTP.Credentials = new NetworkCredential("user", "pass"); reqFTP.Method = WebRequestMethods.Ftp.UploadFile; reqFTP.KeepAlive = false; reqFTP.UseBinary = true; reqFTP.UsePassive = true; reqFTP.ContentLength = stream.Length; reqFTP.EnableSsl = true; // it's FTPES type of ftp int buffLen = 2048; byte[] buff = new byte[buffLen]; int contentLen; try { Stream ftpStream = reqFTP.GetRequestStream(); contentLen = stream.Read(buff, 0, buffLen); while (contentLen != 0) { ftpStream.Write(buff, 0, contentLen); contentLen = stream.Read(buff, 0, buffLen); } ftpStream.Flush(); ftpStream.Close(); } catch (Exception exc) { this.lbl_error.Text = "Error:<br />" + exc.Message; this.lbl_error.Visible = true; return false; } } catch (Exception exc) { this.lbl_error.Text = "Error:<br />" + exc.Message; this.lbl_error.Visible = true; return false; } return true; } Does anyone have idea what may cause this strange behaviour? I think I'm closing all streams accurately. Could this be related with the ftp server settings? The admin said that the ftp handshake never happened second time.

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  • Pointer to 2D array. Why does this example work?

    - by Louise
    I have this code example, but I don't understand why changing the values in the array inside outputUsingArray() are changing the original array. I would have expected changing the values of the array in outputUsingArray() would only be for a local copy of the array. Why isn't that so? However, this is the behaviour I would like, but I don't understand why it work. #include <stdlib.h> #include <stdio.h> void outputUsingArray(int array[][4], int n_rows, int n_cols) { int i, j; printf("Output Using array\n"); for (i = 0; i < n_rows; i++) { for (j = 0; j < n_cols; j++) { // Either can be used. //printf("%2d ", array[i][j] ); printf("%2d ", *(*(array+i)+j)); } printf("\n"); } printf("\n"); array[0][0] = 100; array[2][3] = 200; } void outputUsingPointer(int (*array)[4], int n_rows, int n_cols) { int i, j; printf("Output Using Pointer to Array i.e. int (*array)[4]\n"); for (i = 0; i < n_rows; i++) { for (j = 0; j < n_cols; j++) { printf("%2d ", *(*(array+i) + j )); } printf("\n"); } printf("\n"); } int main() { int array[3][4] = { { 0, 1, 2, 3 }, { 4, 5, 6, 7 }, { 8, 9, 10, 11 } }; outputUsingPointer((int (*)[4])array, 3, 4); outputUsingArray(array, 3, 4); printf("0,0: %i\n", array[0][0]); printf("2,3: %i\n", array[2][3]); return 0; }

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  • PHP/Java Bridge java.lang.NoSuchMethodException

    - by m1sk
    I have setup PHP/Java Bridge with working examples in netbeans tomcat directory. What doesnt work is using custom JAR Here is my code: package com.micha; public class Hello1Bean { public Hello1Bean() {} String hi() {return "This is my hello message";} String hello(String name) {return "Hello" + name;} } And the php code <!DOCTYPE html> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title></title> </head> <body> <?php require_once ("java/Java.inc"); $world = new Java("com.micha.Hello1Bean"); echo java_values($world->hi()); echo "Hello Working Thingy\n\n"; ?> </body> </html> When I check http://localhost:8084/JavaBridge/mytest.php: javax.servlet.ServletException: java.lang.RuntimeException: PHP Fatal error: Uncaught [[o:Exception]:"java.lang.Exception: Invoke failed: [[o:Hello1Bean]]->hi. Cause: java.lang.NoSuchMethodException: hi(). Candidates: [] VM: 1.6.0_25@http://java.sun.com/" at: #-6 php.java.bridge.JavaBridge.checkM(JavaBridge.java:1085) #-5 php.java.bridge.JavaBridge.Invoke(JavaBridge.java:1024) #-4 php.java.bridge.Request.handleRequest(Request.java:417) #-3 php.java.bridge.Request.handleRequests(Request.java:500) #-2 php.java.bridge.http.ContextRunner.run(ContextRunner.java:145) #-1 php.java.bridge.ThreadPool$Delegate.run(ThreadPool.java:60) #0 C:\Users\Micha\.netbeans\7.1.2\apache-tomcat-7.0.22.0_base\webapps\JavaBridge\java\Java.inc(232): java_ThrowExceptionProxyFactory->getProxy(2, 'com.micha.Hello...', 'T', true) #1 C:\Users\Micha\.netbeans\7.1.2\apache-tomcat-7.0.22.0_base\webapps\JavaBridge\java\Java.inc(360): java_Arg->getResult(true) #2 C:\Users\Micha\.netbeans\7.1.2\apache-tomcat-7.0.22.0_base\webapps\JavaBridge\java\Java.inc(366): java_Client->getWrappedResult(true) #3 C:\Users\Micha\.netbean in C:\Users\Micha\.netbeans\7.1.2\apache-tomcat-7.0.22.0_base\webapps\JavaBridge\java\Java.inc on line 195 php.java.servlet.fastcgi.FastCGIServlet.handle(FastCGIServlet.java:499) php.java.servlet.fastcgi.FastCGIServlet.doGet(FastCGIServlet.java:521) javax.servlet.http.HttpServlet.service(HttpServlet.java:621) javax.servlet.http.HttpServlet.service(HttpServlet.java:722) org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393) php.java.servlet.PhpCGIFilter.doFilter(PhpCGIFilter.java:126) Before I had a ClassNotFoundException so it knows there is a a class but for some odd reason I cant call the function. ( if I replace "com.micha.Hello1Bean" with some class that doesnt exist then I get that exception)

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  • Enable real fixed positioning on Samsung Android browsers

    - by Mr. Shiny and New ??
    The Android browser, since 2.2, supports fixed positioning, at least under certain circumstances such as when scaling is turned off. I have a simple HTML file with no JS, but the fixed positioning on three Samsung phones I've tried is simply wrong. Instead of true fixed positioning, the header scrolls out of view then pops back into place after the scrolling is done. This doesn't happen on the Android SDK emulator for any configuration I've tested (2.2, 2.3, 2.3 x86, 4.0.4). It also doesn't happen when using the WebView in an app on the Samsung phones: in those cases the positioning works as expected. Is there a way to make the Samsung Android "stock" browser use real fixed positioning? I've tested: 1. Samsung Galaxy 551, Android 2.2 2. Samsung Galaxy S, Android 2.3 3. Samsung Galaxy S II, Android 2.3 Sample code: <html> <head> <meta name="viewport" content="initial-scale=1.0,maximum-scale=1.0,user-scalable=no,width=device-width,height=device-height"> <style> h1 { position: fixed; top: 0; left: 0; height: 32px; background-color: #CDCDCD; color: black; font-size: 32px; line-height: 32px; padding: 2px; width: 100%; margin: 0;} p { margin-top: 36px; } </style> </head> <body> <h1>Header</h1> <p>Long text goes here</p> </body> </html> The expected behaviour is that the grey header fills the top of the screen and stays put no matter how much you scroll. On Samsung Android browsers it seems to scroll out of view then pop back into place once the scrolling is done, as if the fixed-positioning is being simulated using Javascript, which it isn't. Edit Judging by the comments and "answers" it seems that maybe I wasn't clear on what I need. I am looking for a meta tag or css rule/hack or javascript toggle which turns off Samsung's broken fixed-positioning and turns on the Android browser's working fixed-positioning. I am not looking for a Javascript solution that adds broken fixed-positioning to a browser that has no support whatsoever; the Samsung fixed-positioning does that already, it just looks stupid.

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  • How to produce precisely-timed tone and silence in C#

    - by Bob Denny
    I have a C# project that plays Morse code for RSS feeds. I write it using Managed DirectX, only to discover that Managed DirectX is old and deprecated. The task I have is to play pure sine wave bursts interspersed with silence periods (the code) which are precisely timed as to their duration. I need to be able to call a function which plays a pure tone for so many milliseconds, then Thread.Sleep() then play another, etc. At its fastest, the tones and spaces can be as short as 40ms. It's working quite well in Managed DirectX. To get the precisely timed tone I create 1 sec. of sine wave into a secondary buffer, then to play a tone of a certain duration I seek forward to within x milliseconds of the end of the buffer then play. I've tried System.Media.SoundPlayer. It's a loser because you have to Play(), Sleep(), then Stop() for arbitrary tone lengths. The result is a tone that is too long, variable by CPU load. It takes an indeterminate amount of time to actually stop the tone. I then embarked on a lengthy attempt to use NAudio 1.3. I ended up with a memory resident stream providing the tone data, and again seeking forward leaving the desired length of tone remaining in the stream, then playing. This worked OK on the DirectSoundOut class for a while (see below) but the WaveOut class quickly dies with an internal assert saying that buffers are still on the queue despite PlayerStopped = true. This is odd since I play to the end then put a wait of the same duration between the end of the tone and the start of the next. You'd think that 80ms after starting Play of a 40 ms tone that it wouldn't have buffers on the queue. DirectSoundOut works well for a while, but its problem is that for every tone burst Play() it spins off a separate thread. Eventually (5 min or so) it just stops working. You can see thread after thread after thread exiting in the Output window while running the project in VS2008 IDE. I don't create new objects during playing, I just Seek() the tone stream then call Play() over and over, so I don't think it's a problem with orphaned buffers/whatever piling up till it's choked. I'm out of patience on this one, so I'm asking in the hopes that someone here has faced a similar requirement and can steer me in a direction with a likely solution. Thanks in advance...

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  • UITableViewCell with selectable/copyable text that also detects URLs on the iPhone

    - by Jasarien
    Hi guys, I have a problem. Part of my app requires text to be shown in a table. The text needs to be selectable/copyable (but not editable) and any URLs within the text need to be highlighted and and when tapped allow me to take that URL and open my embedded browser. I have seen a couple of solutions that solve one of either of these problems, but not both. Solution 1: Icon Factory's IFTweetLabel The first solution I tried was to use the IFTweetLabel class made possible by Icon Factory and used in Twitterrific. While this solution allows for links (or anything you can find with a regex) to be detected to be handled on a case by case basis, it doesn't allow for selecting and copying. There is also an issue where if a URL is long enough to be wrapped, the button that the class overlays above the URL to make it interactive cannot wrap and draws off screen, looking very odd. Solution 2: Use IFTweetLabel and handle copy manually The second thing I tried was to keep IFTweetLabel in place to handle the links, but to implement the copying using a long-tap gesture, like how the SMS app handles it. This was just about working, but it doesn't allow for arbitrary selection of text, the whole text is copied, or none is copied at all... Pretty black and white. Solution 3: UITextView My third attempt was to add a UITextView as a subview of the table cell. The only thing that this doesn't solve is the fact that detected URLs cannot be handled by me. The text view uses UIApplication's openURL: method which quits my app and launched Safari. Also, as the table view can get quite large, the number of UITextViews added as subviews cause a noticeable performance drag on scrolling throughout the table, especially on iPhone 3G era devices (because of the creation, layout, compositing whenever a cell is scrolled on screen, etc). So my question to all you knowledgeable folk out there is: What can I do? Would a UIWebView be the best option? Aside from a performance drag, I think a webview would solve all the above issues, and if I remember correctly, back in the 2.0 days, the Apple documentation actually recommended web views where text formatting / hyperlinks were required. Can anyone think of a way to achieve this without a performance drag? Many thanks in advance to everyone who can help.

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  • Why touching "d_name" makes calls to readdir() fail?

    - by Sarah Mani
    Hi, I'm trying to write a little helper for Windows which eventually will accept a file extension as an argument and return the number of files of that kind in the current directory. To do so, I'm reading the file entries in the directories and after getting the extension I'd like to convert it to lowercase to compare it with the yet-to-add specified argument. When converting the extension to lowercase I found that touching even a duplicate string of the d_name variable will cause a strange behaviour, like no more calls to readdir are called. Here is the code I'm using right now (the commented code is preliminary) and outputs for a given directory: #include <ctype.h> #include <dirent.h> #include <stdio.h> #include <string.h> char * strrch(char *string, size_t elements, char character) { char *reverse = string + elements; while (--reverse != string) if (*reverse == character) return reverse; return NULL; } void test(char *string) { // Even being a duplicate will make it fail: char *str = strdup(string); printf("Strings: %s %s\n", string, str); *str = 'a'; printf("Strings: %s %s\n", string, str); //unsigned short int i = 0; //for (; str[i] != '\0', str++; i++) // str[i] = tolower((unsigned char) str[i]); //puts(str); } int main(int argc, char **argv) { DIR *directory; struct dirent *element; if (directory = opendir(".")) { while (element = readdir(directory)) test(strrch(element->d_name, element->d_namlen, '.')); closedir(directory); puts(NULL); } else puts("Couldn't open the directory.\n"); } Output without modifying the duplicate (modification and the second printf call commented): Strings: (null) (null) Strings: . . Strings: .exe .exe Strings: .pdf .pdf Strings: .c .c Strings: .ini .ini Strings: .pdf .pdf Strings: .pdf .pdf Strings: .pdf .pdf Strings: .flac .flac Strings: .FLAC .FLAC Strings: .lnk .lnk Strings: .URL .URL Output of the same directory (with the code above, with the 2 printfs): Strings: (null) (null) Is there anything wrong? Is it a compiler issue? I'm using GCC 4.4.3 in Windows (MinGW) right now. Thank you very much for your help. By the way, is there any other way to work with files and directories in a Windows environment not using the POSIX functions?

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  • "RFC 2833 RTP Event" Consecutive Events and the E "End" Bit

    - by brian_d
    Hello, I can send out a RFC 2833 dtmf event as outlined at http://www.ietf.org/rfc/rfc2833.txt When I do set the E "End" bit, but leave it as 0, I get the following behaviour: If for example keys 7874556332111111145855885#3 were pressed, then ALL events would be sent and show up in a program like wireshark, however only 87456321458585#3 would sound. So the first key (which I figure could be a separate issue) and any repeats of an event (ie 11111) are failing to sound. In section 3.9, figure 2 of the above linked document, they give a 911 example. Here all but the last event have the E bit set. When I set the bit for all numbers, I never get an event to sound. I have thought of a couple possible thing but do not know if they are the reason: 1) figure 2 shows payload types of 96 and 97 sent. I have not nor know how to exactly. In section 3.8, codes 96 and 97 are described as "the dynamic payload types 96 and 97 have been assigned for the redundancy mechanism and the telephone event payload respectively" 2) In section 3.5, "E:", "A sender MAY delay setting the end bit until retransmitting the last packet for a tone, rather than on its first transmission" Does anyone have an idea of how to actually do this? I have also fiddled around with timestamp intervals and the RTP marker. Any help is greatly appreciated. Here is a sample wireshark event capture of the relevant areas: 6590 31.159045000 xx.x.x.xxx --.--.---.-- RTP EVENT Payload type=RTP Event, DTMF Pound # (end) Real-Time Transport Protocol Stream setup by SDP (frame 6225) Setup frame: 6225 Setup Method: SDP 10.. .... = Version: RFC 1889 Version (2) ..0. .... = Padding: False ...0 .... = Extension: False .... 0000 = Contributing source identifiers count: 0 0... .... = Marker: False Payload type: telephone-event (101) Sequence number: 0 Extended sequence number: 65536 Timestamp: 0 Synchronization Source identifier: 0x15f27104 (368210180) RFC 2833 RTP Event Event ID: DTMF Pound # (11) 1... .... = End of Event: True .0.. .... = Reserved: False ..00 0000 = Volume: 0 Event Duration: 2048

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  • Problem getting Java Streams in HP Tandem (Non-Stop)

    - by AndreaG
    Hi. We are porting a simple Java application between Tandem NonStop systems, from G-Series to H-Series. Java version is 1.5.0_02. When performing basic I/O tasks like getting output stream from or opening a client socket, we receive exceptions like java.io.IOException: Value out of range or java.net.SocketException: Value out of range ("value out of range" is Tandem native jargon for, well, quite everything I suppose). Has anybody got similar issues? i.e. I/O corruption while for example messing with JNI? I suppose there is something wrong with the system, but where might it be? Thank you. EDIT: adding snippets as requested sample snippet (a) - using Runtime.exec () (adapted) Properties envVars = new Properties(); Process p = r.exec("/bin/env"); envVars.load(p.getInputStream()); Stack trace (a): java.io.IOException: Value out of range (errno:4034) at java.io.FileInputStream.readBytes(Native Method) at java.io.FileInputStream.read(FileInputStream.java:194) at java.lang.UNIXProcess$DeferredCloseInputStream.read(UNIXProcess.java:221) at java.io.BufferedInputStream.read1(BufferedInputStream.java:254) at java.io.BufferedInputStream.read(BufferedInputStream.java:313) at sun.nio.cs.StreamDecoder$CharsetSD.readBytes(StreamDecoder.java:411) at sun.nio.cs.StreamDecoder$CharsetSD.implRead(StreamDecoder.java:453) at sun.nio.cs.StreamDecoder.read(StreamDecoder.java:183) at java.io.InputStreamReader.read(InputStreamReader.java:167) at java.io.BufferedReader.fill(BufferedReader.java:136) at java.io.BufferedReader.readLine(BufferedReader.java:299) at java.io.BufferedReader.readLine(BufferedReader.java:362) at util.Environment.getVariables(Environment.java:39) Last line fails, and output gets redirected to console (!). sample snippet (b) - using HttpURLConnection: public WorkerThread (HttpURLConnection conn, String requestData, Logger logger) { this.conn = conn; ... } public void run () { OutputStream out = conn.getOutputStream (); } Stack trace (b): java.net.SocketException: Value out of range (errno:4034) at java.net.PlainSocketImpl.socketConnect(Native Method) at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:333) at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:195) at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:182) at java.net.Socket.connect(Socket.java:507) at sun.net.NetworkClient.doConnect(NetworkClient.java:155) at sun.net.www.http.HttpClient.openServer(HttpClient.java:365) at sun.net.www.http.HttpClient.openServer(HttpClient.java:477) at sun.net.www.protocol.https.HttpsClient.<init>(HttpsClient.java:280) at sun.net.www.protocol.https.HttpsClient.New(HttpsClient.java:337) at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.getNewHttpClient(AbstractDelegateHttpsURLConnection.java:176) at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:736) at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:162) at sun.net.www.protocol.http.HttpURLConnection.getOutputStream(HttpURLConnection.java:828) at sun.net.www.protocol.https.HttpsURLConnectionImpl.getOutputStream(HttpsURLConnectionImpl.java:230) Case (a) can be avoided because it was a workaround for other issues with previous JRE version (!), but same behaviour with sockets is really nasty.

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  • Why does UIWebKit throw a structuralComplexityContribution exception?

    - by Axeva
    I've got a simple UIWebView in my iPhone app that's loading a XHTML document with some SGV embeded. This all works find on the desktop version of Safari, but it crashes in a UIWebView. Here is the Objective C: NSString *path = [[NSBundle mainBundle] pathForResource:@"test" ofType:@"html"]; NSData *fileData = [NSData dataWithContentsOfFile: path]; [svgView loadData: fileData MIMEType: @"text/xml" textEncodingName: @"UTF-8" baseURL: [NSURL fileURLWithPath: path]]; I also tried a MIMEType of application/xhtml+xml, but it didn't help. Here is the HTML: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>XTech SVG Demo</title> </head> <body> <svg xmlns="http://www.w3.org/2000/svg"> <g style="fill-opacity:0.7;"> <circle cx="6.5cm" cy="2cm" r="100" style="fill:red; stroke:black; stroke-width:0.1cm" transform="translate(0,50)" /> <circle cx="6.5cm" cy="2cm" r="100" style="fill:blue; stroke:black; stroke-width:0.1cm" transform="translate(70,150)" /> <circle cx="6.5cm" cy="2cm" r="100" style="fill:green; stroke:black; stroke-width:0.1cm" transform="translate(-70,150)"/> </g> </svg> </body> </html> All very basic stuff. When it loads on the iPhone, however, it crashes with this error: 2010-03-31 10:37:10.252 ColorDoodle[2014:20b] -[DOMElement structuralComplexityContribution]: unrecognized selector sent to instance 0x3e51b60 2010-03-31 10:37:10.253 ColorDoodle[2014:20b] Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: ' -[DOMElement structuralComplexityContribution]: unrecognized selector sent to instance 0x3e51b60' Any idea why? Is this a bug in the rendering engine of the UIWebView? I don't see anything too odd here. * Updated * There is definitely something screwy going on here. If I add this bit of code just inside the tag, it works fine: <form> </form> Take that code back out, and it crashes again.

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  • VB6 app not executing as scheduled task unless user is logged on

    - by Tedd Hansen
    Hi Would greatly apprechiate some help on this one! It may be a tricky one. :) Problem I have an VB6 application which is set up as scheduled task. It starts every time, but when executing CreateObject it fails if user is not logged on to computer. I am looking for information on what could cause this. Primary suspicion is that some Windows API fails. Key points Behaviour confirmed on Windows 2000, 2003, 2008 and Vista. The application executes as user X at scheduled time, executed by Windows Task Scheduler. It executes every time. Application does start! -- If user X is logged on via RDP it runs perfectly. (Note that user doesn't need to be connected, only logged on) -- If user X is not logged on to computer the application fails. Failure point Application fails when using CreateObject() to instansiate a DCOM object which is also part of the application. The DCOM objects declare .dll-references at startup (globally/on top of .bas-file) and run a small startup function. Failure must be during startup, possibly in one of the .dll-declarations. Thoughts After some Googling my initial suspicion was directed at MAPI. From what I could see MAPI required user to be logged on. The application has MAPI references. But even with all MAPI references removed it still does not work. What is the difference if an user is logged on? Registry mapping? Environment? explorer.exe is running. Isn't the user logged on when application executes as the user? What info would help? A definitive answer would be truly great. Any information regarding any VB6 feature/Windows API that could act differently depending on wether user is logged on or not would definitively help. Similar experiences may lead me in the right direction. Tips on debuggin this. Thanks! :)

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  • PHP mysqli wrapper: passing by reference with __call() and call_user_func_array()

    - by Dave
    Hi everyone. I'm a long running fan of stackoverflow, first time poster. I'd love to see if someone can help me with this. Let me dig in with a little code, then I'll explain my problem. I have the following wrapper classes: class mysqli_wrapper { private static $mysqli_obj; function __construct() // Recycles the mysqli object { if (!isset(self::$mysqli_obj)) { self::$mysqli_obj = new mysqli(MYSQL_SERVER, MYSQL_USER, MYSQL_PASS, MYSQL_DBNAME); } } function __call($method, $args) { return call_user_func_array(array(self::$mysqli_obj, $method), $args); } function __get($para) { return self::$mysqli_obj->$para; } function prepare($query) // Overloaded, returns statement wrapper { return new mysqli_stmt_wrapper(self::$mysqli_obj, $query); } } class mysqli_stmt_wrapper { private $stmt_obj; function __construct($link, $query) { $this->stmt_obj = mysqli_prepare($link, $query); } function __call($method, $args) { return call_user_func_array(array($this->stmt_obj, $method), $args); } function __get($para) { return $this->stmt_obj->$para; } // Other methods will be added here } My problem is that when I call bind_result() on the mysqli_stmt_wrapper class, my variables don't seem to be passed by reference and nothing gets returned. To illustrate, if I run this section of code, I only get NULL's: $mysqli = new mysqli_wrapper; $stmt = $mysqli->prepare("SELECT cfg_key, cfg_value FROM config"); $stmt->execute(); $stmt->bind_result($cfg_key, $cfg_value); while ($stmt->fetch()) { var_dump($cfg_key); var_dump($cfg_value); } $stmt->close(); I also get a nice error from PHP which tells me: PHP Warning: Parameter 1 to mysqli_stmt::bind_result() expected to be a reference, value given in test.php on line 48 I've tried to overload the bind_param() function, but I can't figure out how to get a variable number of arguments by reference. func_get_args() doesn't seem to be able to help either. If I pass the variables by reference as in $stmt->bind_result(&$cfg_key, &$cfg_value) it should work, but this is deprecated behaviour and throws more errors. Does anyone have some ideas around this? Thanks so much for your time.

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  • How do I reward my developers for the little things they get right?

    - by Nat
    I am in a tech lead role and my developers get stuff right most of the time. How do I communicate to them thier value to me? (I.e. they have value because I do not have to go through and point out mistakes which means I do not have to watch them like a hawk which frees me to do more useful things). In summary For doing the mundane well on a day to day basis, it is good to recognise the developers effort verbally to them. An honest thankyou that mentions the specific behaviour and its positive repercussions to you personally will be well received, adjust the language to suite each individual. (Note that other developers within earshot may also respond to this by increasing their efforts in this specific activity.) Other things that should be done regularly are: Team drinks In many cultures this is an entirely worthy way of giving the team some time to socialise and relax. Be sure that you do not exclude people who do not drink or are not keen on pub culture. Shared meals are another option. Formal written (email) acknowledgment and praise to senior managers of the teams efforts and successes. (Note that acknowledging individuals alone may damage team spirit) Work the hours you expect your team to do. If they absolutely must work late for a deadline, be there in support Go to bat for the team. Refuse to let them be forced to work long periods of overtime without compensation. Protect them from level politics and stress. Give your team the best equipment you can afford. Good tools show respect and improve productivity. Small or large team rewards where appropriate can consist of many interesting activities/ items. If it allows the team to get together in a fun and even lightly competitive manner it will work (foosball table, go-karting, darts board, video game console etc). Don’t forget to listen to what the team wants, each team will have different ideas. Ensure they are getting a fair deal financially from the company. While different people may have different expectations of their pay, someone being paid unfairly will rot morale for the entire team

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  • Beautifulsoup recursive attribute

    - by Marcos Placona
    Hi, trying to parse an XML with Beautifulsoup, but hit a brick wall when trying to use the "recursive" attribute with findall() I have a pretty odd xml format shown below: <?xml version="1.0"?> <catalog> <book id="bk101"> <author>Gambardella, Matthew</author> <title>XML Developer's Guide</title> <genre>Computer</genre> <price>44.95</price> <publish_date>2000-10-01</publish_date> <description>An in-depth look at creating applications with XML.</description> <catalog>true</catalog> </book> <book id="bk102"> <author>Ralls, Kim</author> <title>Midnight Rain</title> <genre>Fantasy</genre> <price>5.95</price> <publish_date>2000-12-16</publish_date> <description>A former architect battles corporate zombies, an evil sorceress, and her own childhood to become queen of the world.</description> <catalog>false</catalog> </book> </catalog> As you can see, the catalog tag repeats inside the book tag, which causes an error when I try to to something like: from BeautifulSoup import BeautifulStoneSoup as BSS catalog = "catalog.xml" def open_rss(): f = open(catalog, 'r') return f.read() def rss_parser(): rss_contents = open_rss() soup = BSS(rss_contents) items = soup.findAll('catalog', recursive=False) for item in items: print item.title.string rss_parser() As you will see, on my soup.findAll I've added recursive=false, which in theory would make it no recurse through the item found, but skip to the next one. This doesn't seem to work, as I always get the following error: File "catalog.py", line 17, in rss_parser print item.title.string AttributeError: 'NoneType' object has no attribute 'string' I'm sure I'm doing something stupid here, and would appreciate if someone could give me some help on how to solve this problem. Changing the HTML structure is not an option, this this code needs to perform well as it will potentially parse a large XML file. Thanks in advance, Marcos

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  • ExecuteNonQuery on a stored proc causes it to be deleted

    - by FinancialRadDeveloper
    This is a strange one. I have a Dev SQL Server which has the stored proc on it, and the same stored proc when used with the same code on the UAT DB causes it to delete itself! Has anyone heard of this behaviour? SQL Code: -- Check if user is registered with the system IF OBJECT_ID('dbo.sp_is_valid_user') IS NOT NULL BEGIN DROP PROCEDURE dbo.sp_is_valid_user IF OBJECT_ID('dbo.sp_is_valid_user') IS NOT NULL PRINT '<<< FAILED DROPPING PROCEDURE dbo.sp_is_valid_user >>>' ELSE PRINT '<<< DROPPED PROCEDURE dbo.sp_is_valid_user >>>' END go create procedure dbo.sp_is_valid_user @username as varchar(20), @isvalid as int OUTPUT AS BEGIN declare @tmpuser as varchar(20) select @tmpuser = username from CPUserData where username = @username if @tmpuser = @username BEGIN select @isvalid = 1 END else BEGIN select @isvalid = 0 END END GO Usage example DECLARE @isvalid int exec dbo.sp_is_valid_user 'username', @isvalid OUTPUT SELECT valid = @isvalid The usage example work all day... when I access it via C# it deletes itself in the UAT SQL DB but not the Dev one!! C# Code: public bool IsValidUser(string sUsername, ref string sErrMsg) { string sDBConn = ConfigurationSettings.AppSettings["StoredProcDBConnection"]; SqlCommand sqlcmd = new SqlCommand(); SqlDataAdapter sqlAdapter = new SqlDataAdapter(); try { SqlConnection conn = new SqlConnection(sDBConn); sqlcmd.Connection = conn; conn.Open(); sqlcmd.CommandType = CommandType.StoredProcedure; sqlcmd.CommandText = "sp_is_valid_user"; // params to pass in sqlcmd.Parameters.AddWithValue("@username", sUsername); // param for checking success passed back out sqlcmd.Parameters.Add("@isvalid", SqlDbType.Int); sqlcmd.Parameters["@isvalid"].Direction = ParameterDirection.Output; sqlcmd.ExecuteNonQuery(); int nIsValid = (int)sqlcmd.Parameters["@isvalid"].Value; if (nIsValid == 1) { conn.Close(); sErrMsg = "User Valid"; return true; } else { conn.Close(); sErrMsg = "Username : " + sUsername + " not found."; return false; } } catch (Exception e) { sErrMsg = "Error :" + e.Source + " msg: " + e.Message; return false; } }

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  • Why differs floating-point precision in C# when separated by parantheses and when separated by state

    - by Andreas Larsen
    I am aware of how floating point precision works in the regular cases, but I stumbled on an odd situation in my C# code. Why aren't result1 and result2 the exact same floating point value here? const float A; // Arbitrary value const float B; // Arbitrary value float result1 = (A*B)*dt; float result2 = (A*B); result2 *= dt; From this page I figured float arithmetic was left-associative and that this means values are evaluated and calculated in a left-to-right manner. The full source code involves XNA's Quaternions. I don't think it's relevant what my constants are and what the VectorHelper.AddPitchRollYaw() does. The test passes just fine if I calculate the delta pitch/roll/yaw angles in the same manner, but as the code is below it does not pass: X Expected: 0.275153548f But was: 0.275153786f [TestFixture] internal class QuaternionPrecisionTest { [Test] public void Test() { JoystickInput input; input.Pitch = 0.312312432f; input.Roll = 0.512312432f; input.Yaw = 0.912312432f; const float dt = 0.017001f; float pitchRate = input.Pitch * PhysicsConstants.MaxPitchRate; float rollRate = input.Roll * PhysicsConstants.MaxRollRate; float yawRate = input.Yaw * PhysicsConstants.MaxYawRate; Quaternion orient1 = Quaternion.Identity; Quaternion orient2 = Quaternion.Identity; for (int i = 0; i < 10000; i++) { float deltaPitch = (input.Pitch * PhysicsConstants.MaxPitchRate) * dt; float deltaRoll = (input.Roll * PhysicsConstants.MaxRollRate) * dt; float deltaYaw = (input.Yaw * PhysicsConstants.MaxYawRate) * dt; // Add deltas of pitch, roll and yaw to the rotation matrix orient1 = VectorHelper.AddPitchRollYaw( orient1, deltaPitch, deltaRoll, deltaYaw); deltaPitch = pitchRate * dt; deltaRoll = rollRate * dt; deltaYaw = yawRate * dt; orient2 = VectorHelper.AddPitchRollYaw( orient2, deltaPitch, deltaRoll, deltaYaw); } Assert.AreEqual(orient1.X, orient2.X, "X"); Assert.AreEqual(orient1.Y, orient2.Y, "Y"); Assert.AreEqual(orient1.Z, orient2.Z, "Z"); Assert.AreEqual(orient1.W, orient2.W, "W"); } } Granted, the error is small and only presents itself after a large number of iterations, but it has caused me some great headackes.

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  • C# - How to override GetHashCode with Lists in object

    - by Christian
    Hi, I am trying to create a "KeySet" to modify UIElement behaviour. The idea is to create a special function if, eg. the user clicks on an element while holding a. Or ctrl+a. My approach so far, first lets create a container for all possible modifiers. If I would simply allow a single key, it would be no problem. I could use a simple Dictionary, with Dictionary<Keys, Action> _specialActionList If the dictionary is empty, use the default action. If there are entries, check what action to use depending on current pressed keys And if I wasn't greedy, that would be it... Now of course, I want more. I want to allow multiple keys or modifiers. So I created a wrapper class, wich can be used as Key to my dictionary. There is an obvious problem when using a more complex class. Currently two different instances would create two different key, and thereby he would never find my function (see code to understand, really obvious) Now I checked this post: http://stackoverflow.com/questions/638761/c-gethashcode-override-of-object-containing-generic-array which helped a little. But my question is, is my basic design for the class ok. Should I use a hashset to store the modifier and normal keyboardkeys (instead of Lists). And If so, how would the GetHashCode function look like? I know, its a lot of code to write (boring hash functions), some tips would be sufficient to get me started. Will post tryouts here... And here comes the code so far, the Test obviously fails... public class KeyModifierSet { private readonly List<Key> _keys = new List<Key>(); private readonly List<ModifierKeys> _modifierKeys = new List<ModifierKeys>(); private static readonly Dictionary<KeyModifierSet, Action> _testDict = new Dictionary<KeyModifierSet, Action>(); public static void Test() { _testDict.Add(new KeyModifierSet(Key.A), () => Debug.WriteLine("nothing")); if (!_testDict.ContainsKey(new KeyModifierSet(Key.A))) throw new Exception("Not done yet, help :-)"); } public KeyModifierSet(IEnumerable<Key> keys, IEnumerable<ModifierKeys> modifierKeys) { foreach (var key in keys) _keys.Add(key); foreach (var key in modifierKeys) _modifierKeys.Add(key); } public KeyModifierSet(Key key, ModifierKeys modifierKey) { _keys.Add(key); _modifierKeys.Add(modifierKey); } public KeyModifierSet(Key key) { _keys.Add(key); } }

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  • Linked List Design

    - by Jim Scott
    The other day in a local .NET group I attend the following question came up: "Is it a valid interview question to ask about Linked Lists when hiring someone for a .NET development position?" Not having a computer sciense degree and being a self taught developer my response was that I did not feel it was appropriate as I in 5 years of developer with .NET had never been exposed to linked lists and did not hear any compeling reason for a use for one. However the person commented that it is a very common interview question so I decided when I left that I would do some reasearch on linked lists and see what I might be missing. I have read a number of posts on stack overflow and various google searches and decided the best way to learn about them was to write my own .NET classes to see how they worked from the inside out. Here is my class structure Single Linked List Constructor public SingleLinkedList(object value) Public Properties public bool IsTail public bool IsHead public object Value public int Index public int Count private fields not exposed to a property private SingleNode firstNode; private SingleNode lastNode; private SingleNode currentNode; Methods public void MoveToFirst() public void MoveToLast() public void Next() public void MoveTo(int index) public void Add(object value) public void InsertAt(int index, object value) public void Remove(object value) public void RemoveAt(int index) Questions I have: What are typical methods you would expect in a linked list? What is typical behaviour when adding new records? For example if I have 4 nodes and I am currently positioned in the second node and perform Add() should it be added after or before the current node? Or should it be added to the end of the list? Some of the designs I have seen explaining things seem to expose outside of the LinkedList class the Node object. In my design you simply add, get, remove values and know nothing about any node object. Should the Head and Tail be placeholder objects that are only used to define the head/tail of the list? I require my Linked List be instantiated with a value which creates the first node of the list which is essentially the head and tail of the list. Would you change that ? What should the rules be when it comes to removing nodes. Should someone be able to remove all nodes? Here is my Double Linked List Constructor public DoubleLinkedList(object value) Properties public bool IsHead public bool IsTail public object Value public int Index public int Count Private fields not exposed via property private DoubleNode currentNode; Methods public void AddFirst(object value) public void AddLast(object value) public void AddBefore(object existingValue, object value) public void AddAfter(object existingValue, object value) public void Add(int index, object value) public void Add(object value) public void Remove(int index) public void Next() public void Previous() public void MoveTo(int index)

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  • _heapwalk reports _HEAPBADNODE, causes breakpoint or loops endlessly

    - by Stefan Hubert
    I use _heapwalk to gather statistics about the Process' standard heap. Under certain circumstances i observe unexpected behaviours like: _HEAPBADNODE is returned some breakpoint is triggered inside _heapwalk, telling me the heap might got corrupted access violation inside _heapWalk. I saw different behaviours on different Computers. On one Windows XP 32 bit machine everything looked fine, whereas on two Windows XP 64 bit machines i saw the mentioned symptoms. I saw this behaviour only if LowFragmentationHeap was enabled. I played around a bit. I walked the heap several times right one after another inside my program. First time doing nothing in between the subsequent calls to _heapWalk (everything fine). Then again, this time doing some stuff (for gathering statistics) in between two subsequent calls to _heapWalk. Depending upon what I did there, I sometimes got the described symptoms. Here finally a question: What exactly is safe and what is not safe to do in between two subsequent calls to _heapWalk during a complete heap walk run? Naturally, i shall not manipulate the heap. Therefore i doublechecked that i don't call new and delete. However, my observation is that function calls with some parameter passing causes my heap walk run to fail already. I subsequently added function calls and increasing number of parameters passed to these. My feeling was two function calls with two paramters being passed did not work anymore. However I would like to know why. Any ideas why this does not happen on some machines? Any ideas why this only happens if LowFragmentationHeap is enabled? Sample Code finally: #include <malloc.h> void staticMethodB( int a, int b ) { } void staticMethodA( int a, int b, int c) { staticMethodB( 3, 6); return; } ... _HEAPINFO hinfo; hinfo._pentry = NULL; while( ( heapstatus = _heapwalk( &hinfo ) ) == _HEAPOK ) { //doing nothing here works fine //however if i call functions here with parameters, this causes //_HEAPBADNODE or something else staticMethodA( 3,4,5); } switch( heapstatus ) { ... case _HEAPBADNODE: assert( false ); /*ERROR - bad node in heap */ break; ...

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  • How to get this Qt state machine to work?

    - by Ton van den Heuvel
    I have two widgets that can be checked, and a numeric entry field that should contain a value greater than zero. Whenever both widgets have been checked, and the numeric entry field contains a value greater than zero, a button should be enabled. I am struggling with defining a proper state machine for this situation. So far I have the following: QStateMachine *machine = new QStateMachine(this); QState *buttonDisabled = new QState(QState::ParallelStates); buttonDisabled->assignProperty(ui_->button, "enabled", false); QState *a = new QState(buttonDisabled); QState *aUnchecked = new QState(a); QFinalState *aChecked = new QFinalState(a); aUnchecked->addTransition(wa, SIGNAL(checked()), aChecked); a->setInitialState(aUnchecked); QState *b = new QState(buttonDisabled); QState *bUnchecked = new QState(b); QFinalState *bChecked = new QFinalState(b); employeeUnchecked->addTransition(wb, SIGNAL(checked()), bChecked); b->setInitialState(bUnchecked); QState *weight = new QState(registerButtonDisabled); QState *weightZero = new QState(weight); QFinalState *weightGreaterThanZero = new QFinalState(weight); weightZero->addTransition(this, SIGNAL(validWeight()), weightGreaterThanZero); weight->setInitialState(weightZero); QState *buttonEnabled = new QState(); buttonEnabled->assignProperty(ui_->registerButton, "enabled", true); buttonDisabled->addTransition(buttonDisabled, SIGNAL(finished()), buttonEnabled); buttonEnabled->addTransition(this, SIGNAL(invalidWeight()), weightZero); machine->addState(registerButtonDisabled); machine->addState(registerButtonEnabled); machine->setInitialState(registerButtonDisabled); machine->start(); The problem here is that the following transition: buttonEnabled->addTransition(this, SIGNAL(invalidWeight()), weightZero); causes all the child states in the registerButtonDisabled state to be reverted to their initial state. This is unwanted behaviour, as I want the a and b states to remain in the same state. How do I prevent this?

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