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  • How can a B-tree node be represented?

    - by chronodekar
    We're learning B-trees in class and have been asked to implement them in code. The teacher has left choice of programming language to us and I want to try and do it in C#. My problem is that the following structure is illegal in C#, unsafe struct BtreeNode { int key_num; // The number of keys in a node int[] key; // Array of keys bool leaf; // Is it a leaf node or not? BtreeNode*[] c; // Pointers to next nodes } Specifically, one is not allowed to create a pointer to point to the structure itself. Is there some work-around or alternate approach I could use? I'm fairly certain that there MUST be a way to do this within the managed code, but I can't figure it out. EDIT: Eric's answer pointed me in the right direction. Here's what I ended up using, class BtreeNode { public List<BtreeNode> children; // The child nodes public static int MinDeg; // The Minimum Degree of the tree public bool IsLeaf { get; set; } // Is the current node a leaf or not? public List<int> key; // The list of keys ... }

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  • Blackberry screen navigation probelm

    - by dalandroid
    I have a Screen name DownloaderScreen when the screen start it will start download some file and when download is complete it will go forward to next screen autometically. I using the following code. public DownloaderScreen() { super(NO_VERTICAL_SCROLL | NO_HORIZONTAL_SCROLL | USE_ALL_HEIGHT | USE_ALL_WIDTH); this.application = UiApplication.getUiApplication(); HorizontalFieldManager outerBlock = new HorizontalFieldManager(USE_ALL_HEIGHT); VerticalFieldManager innerBlock = new VerticalFieldManager(USE_ALL_WIDTH | FIELD_VCENTER); innerBlock.setPadding(0, 10, 0, 10); outerBlock.setBackground(BackgroundFactory .createBitmapBackground(LangValue.dlBgimg)); outerBlock.add(innerBlock); add(outerBlock); phraseHelper = new PhraseHelper(); final String[][] phraseList = phraseHelper.getDownloadList(); gaugeField = new GaugeField("Downloading ", 0, phraseList.length, 0, GaugeField.PERCENT); innerBlock.add(gaugeField); Thread dlTread = new Thread() { public void run() { startDownload(phraseList); } }; dlTread.start(); } private void startDownload(String[][] phraseList){ if(phraseList.length!=0){ for(int i=0; i < phraseList.length ; i++){// gaugeField.setValue(i); // code for download } } goToNext(); } private void goToNext() { final Screen currentScreen = application.getActiveScreen(); if (UiApplication.isEventDispatchThread()) { application.popScreen(currentScreen); application.pushScreen(new HomeScreen()); } else { application.invokeLater(new Runnable() { public void run() { application.popScreen(currentScreen); application.pushScreen(new HomeScreen()); } }); } } The code is working fine and starts download files and when download is completed it is going forward to next screen. But when there is no file to download phraseList array length is zero, it is not going forward. What is problem in my code?

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  • HTTP post using php and curl failing

    - by user2916484
    I am trying to send an XML file to an external system. I am using the below code for doing so, which I got over the internet. But I observed that when i put an echo on the xml variable, it does not show me the XML as a string, but it is parsing the xml and showing me the values. Same is happening when I am sending this to external system. Which is failing. Can you please tell me a way, in which the XML is not parsed and I can send the entire XML text as a string to external system? My code is below. <?php $xml = '<?xml version=\"1.0\" encoding="UTF-8" ?><shiporder><orderID>1234</orderID> <orderperson>John Smith</orderperson></shiporder>'; $xml2 = ''; $headers = array( "Content-type: text/xml", "Content-length: " . strlen($xml), "Connection: close", ); // give the path of the Third party site $url = "http://<server>:<port>/XMII/Illuminator?service=WSMessageListener&mode=WSMessageListenerServer&NAME=shiporder&IllumLoginName=<name>&IllumLoginPassword=<pswd>"; echo $xml; echo $url; $ch = curl_init(); curl_setopt($ch, CURLOPT_URL,$url); //curl_setopt($ch, CURLOPT_MUTE, 1); curl_setopt($ch, CURLOPT_POST, 1); curl_setopt($ch, CURLOPT_TIMEOUT, 10); curl_setopt($ch, CURLOPT_HTTPHEADER, $headers); curl_setopt($ch, CURLOPT_POSTFIELDS, $xml); curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1); $output = curl_exec($ch); echo $output; curl_close($ch); ?> Regards, Gita

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  • Automatically update php loop with data pulled from database

    - by John Svensson
    SQL STRUCTURE CREATE TABLE IF NOT EXISTS `map` ( `id` int(11) NOT NULL AUTO_INCREMENT, `x` int(11) NOT NULL, `y` int(11) NOT NULL, `type` varchar(50) NOT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=3 ; http://localhost/map.php?x=0&y=0 When I update the x and y via POST or GET, I would like to pull the new data from the database without refreshing the site, how would I manage that? Could someone give me some examples, because I am really stuck here. <?php mysql_connect('localhost', 'root', ''); mysql_select_db('hol'); $startX = $_GET['x']; $startY = $_GET['y']; $fieldHeight = 6; $fieldWidth = 6; $sql = "SELECT id, x, y, type FROM map WHERE x BETWEEN ".$startX." AND ".($startX+$fieldWidth). " AND y BETWEEN ".$startY." AND ".($startY+$fieldHeight); $result = mysql_query($sql); $positions = array(); while ($row = mysql_fetch_assoc($result)) { $positions[$row['x']][$row['y']] = $row; } echo "<table>"; for($y=$startY; $y<$startY+$fieldHeight; $y++) { echo "<tr>"; for($x=$startX; $x<$startX+$fieldWidth; $x++) { echo "<td>"; if(isset($positions[$x][$y])) { echo $positions[$x][$y]['type']; } else { echo "(".$x.",".$y.")"; } echo "</td>"; } echo "</tr>"; } echo "</table>"; ?>

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  • Creating a Variable From Two Others

    - by John
    Hello, In the HTML table below, I would like to add a third column that equals $row["countSubmissions"] times 10 plus $row["countComments"]. How could I do this? Thanks in advance, John $sqlStr = "SELECT l.loginid, l.username, COALESCE(s.total, 0) AS countSubmissions, COALESCE(c.total, 0) AS countComments FROM login l LEFT JOIN ( SELECT loginid, COUNT(1) AS total FROM submission GROUP BY loginid ) s ON l.loginid = s.loginid LEFT JOIN ( SELECT loginid, COUNT(1) AS total FROM comment GROUP BY loginid ) c ON l.loginid = c.loginid GROUP BY l.loginid ORDER BY countSubmissions DESC LIMIT 10"; $result = mysql_query($sqlStr); $arr = array(); echo "<table class=\"samplesrec1edit\">"; while ($row = mysql_fetch_array($result)) { echo '<tr>'; echo '<td class="sitename1edit1"><a href="http://www...com/.../members/index.php?profile='.$row["username"].'">'.stripslashes($row["username"]).'</a></td>'; echo '<td class="sitename1edit2">'.stripslashes($row["countSubmissions"]).'</td>'; echo '<td class="sitename1edit2">'.stripslashes($row["countComments"]).'</td>'; echo '</tr>'; } echo "</table>";

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  • How do I display core data on second view controller?

    - by jon
    I am working on my first core data iPhone application. I am using a navigation controller, and the root view controller displays 4 rows. Clicking the first row takes me to a second table view controller. However, when I click the back button, repeat the row tap, click the back button again, and tap the row a third time, I get an error. I have been researching this for a week with no success. I can reproduce the error easily: Create a new Navigation-based Application, use Core Data for storage, call it MyTest which creates MyTestAppDelegate and RootViewController. Add new UIViewController subclass, with UITableViewController and xib, call it ListViewController. Copy code from RootViewController.h and .m to ListViewController.h and .m., changing the file names appropriately. To simplify the code, I removed the trailing “_” from all variables. In RootViewController, I added #import ListViewController.h, set up an array to display 4 rows and navigate to ListViewController when clicking the first row. In ListViewController.m, I added #import MyTestAppDelegate.h” and the following code: - (void)viewDidLoad { [super viewDidLoad]; if (managedObjectContext == nil) { managedObjectContext = [(MyTestAppDelegate *)[[UIApplication sharedApplication] delegate] managedObjectContext]; } .. } The sequence that causes the error is tap row, return, tap row, return, tap row - error. managedObjectContext is synthesized for the third time. I appreciate your patience and your help, as this makes no sense to me. ADDENDUM: I may have a partial solution. http://www.iphonedevsdk.com/forum/iphone-sdk-development/41688-accessing-app-delegates-managed-object-context.html If I do not release the managedObjectContext in the .m file, the error goes away. Is that ok or will that cause me issues? - (void)dealloc { [fetchedResultsController release]; // [managedObjectContext release]; [super dealloc]; } ADDENDUM 2: See solution below. Sorry for the formatting issues - this was my first post.

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  • RegExpValidator never matches

    - by babyangel86
    Hi, I've got a class that's meant to validate input fields to make sure the value is always a decimal. I've tested the regex here: http://livedocs.adobe.com/flex/3/html/help.html?content=validators_7.html, and it looks like it does the right thing, but in my app, I can't seem to get it to match to a number format. Class Definition: public class DecimalValidator { //------------------------------- ATTRIBUTES public var isDecimalValidator:RegExpValidator; //------------------------------- CONSTRUCTORS public function DecimalValidator() { isDecimalValidator = new RegExpValidator(); isDecimalValidator.expression = "^-?(\d+\.\d*|\.\d+)$"; isDecimalValidator.flags = "g"; isDecimalValidator.required = true; isDecimalValidator.property = "text"; isDecimalValidator.triggerEvent = FocusEvent.FOCUS_OUT; isDecimalValidator.noMatchError = "Float Expected"; } } Setting the source here: public function registerDecimalInputValidator(inputBox:TextInput, valArr:Array):void { // Add Validators var dValidator:DecimalValidator = new DecimalValidator(); dValidator.isDecimalValidator.source = inputBox; dValidator.isDecimalValidator.trigger = inputBox; inputBox.restrict = "[0-9].\\.\\-"; inputBox.maxChars = 10; valArr.push(dValidator.isDecimalValidator); } And Calling it here: registerDecimalInputValidator(textInput, validatorArr); Where textInput is an input box created earlier. Clearly I'm missing something simple yet important, but I'm not entirely sure what! Any help would be much appreciated.

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  • How to do something when AVQueuePlayer finishes the last playeritem

    - by user1634529
    I've got an AVQueuePlayer which I'm creating from an array of 4 AVPlayerItems, and it all plays fine. I want to do something when the last item in the queue finishes playing, I've looked a load of answers on here and this is the one that looks most promising for what I want: The best way to execute code AFTER a sound has finished playing In my button handler i have this code: static const NSString *ItemStatusContext; [thePlayerItemA addObserver:self forKeyPath:@"status" options:0 context:&ItemStatusContext]; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(playerItemDidReachEnd) name:AVPlayerItemDidPlayToEndTimeNotification object:thePlayerItemA]; theQueuePlayer = [AVQueuePlayer playerWithPlayerItem:thePlayerItemA]; [theQueuePlayer play]; and then I have a function to handle playerItemDidReachEnd: - (void)playerItemDidReachEnd:(NSNotification *)notification { // Do stuff here NSLog(@"IT REACHED THE END"); } But when I run this I get an Internal Inconsistency Exception: An -observeValueForKeyPath:ofObject:change:context: message was received but not handled. Key path: status Observed object: <AVPlayerItem: 0x735a130, asset = <AVURLAsset: 0x73559c0, URL = file://localhost/Users/mike/Library/Application%20Support/iPhone%20Simulator/5.0/Applications/A0DBEC13-2DA6-4887-B29D-B43A78E173B8/Phonics%2001.app/yes.mp3>> Change: { kind = 1; } What am I doing wrong?

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  • is_dir does not recognize folders

    - by Rakoon
    Hi I am trying to make a function that scans a folder for subfolders and then returns a numeric array with the names of those folders. This is the code i use for testing. Once i get it to print out the folder names and not just "." and ".." for present and above folder all will be well, and I can finish the function. <?php function super_l_getthemes($dir="themes") { if ($handle = opendir($dir)) { echo "Handle: {$handle}\n"; echo "Files:\n"; while (false !== ($file = readdir($handle))) { echo "{$file}<br>"; } closedir($handle); } ?> The above code works fine, and prints out all the contents of the folder: files, subfolders and the "." and ".." but if i replace: while (false !== ($file = readdir($handle))) { echo "{$file}<br>"; } with: while (false !== ($file = readdir($handle))) { if(file_exists($file) && is_dir($file)){echo "{$file}";} } The function only prints "." and ".." , not the two folder names that I'd like it to print. Any help is appreciated.

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  • why doesnt this program print?

    - by Alex
    What I'm trying to do is to print my two-dimensional array but i'm lost. The first function is running perfect, the problem is the second or maybe the way I'm passing it to the "Print" function. #include <stdio.h> #include <stdlib.h> #define ROW 2 #define COL 2 //Memory allocation and values input void func(int **arr) { int i, j; arr = (int**)calloc(ROW,sizeof(int*)); for(i=0; i < ROW; i++) arr[i] = (int*)calloc(COL,sizeof(int)); printf("Input: \n"); for(i=0; i<ROW; i++) for(j=0; j<COL; j++) scanf_s("%d", &arr[i][j]); } //This is where the problem begins or maybe it's in the main void print(int **arr) { int i, j; for(i=0; i<ROW; i++) { for(j=0; j<COL; j++) printf("%5d", arr[i][j]); printf("\n"); } } void main() { int *arr; func(&arr); print(&arr); //maybe I'm not passing the arr right ? }

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  • can't upload greater 50MB

    - by Syom
    i want to upload two files. here is the script <? ini_set('memory_limit', "400M"); ini_set('file_uploads', "5"); ini_set('max_execution_time', "900"); ini_set('upload_max_filesize', "400M"); ini_set('post_max_size', "400M"); ?> <form action="form.php" method="post" enctype="multipart/form-data" /> <input type="file" name="video" /> <input type="file" name="picture" > <input type="submit" class="input" value="?????" /> </form> form.php: <? ini_set('memory_limit', "400M"); ini_set('file_uploads', "5"); ini_set('max_execution_time', "900"); ini_set('upload_max_filesize', "400M"); ini_set('post_max_size', "400M"); print_r($_FILES); //returns Array ( ) ?> i've asked about this question here , and i've set ini_set(...) as you see, but when i try to upload the file greater than 50MB, it doesn't happen. could you tell me why?

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  • TCP/IP Implementation General Questions

    - by user2971023
    I've implemented the concepts shown here; http://wiki.unity3d.com/index.php/Simple_TCP/IP_Client_-_Server outside of unity and it works. (though i had to create the TCPIPServerApp from scratch as i could not find the base project anywhere). I have some general questions on how to use tcp/ip properly however. I've done some research on tcp/ip itself but I'm still a little confused. It seems like using the method above doesn't guarantee that I'll see the message (res). It just checks on every update to see if there is a different message in res. What if multiple messages are sent and the program lags or something, will i miss the earlier packet(s)? Should i instead do an array so it stores the last X messages? How do i know the data was received? Do I need to add a message id and build in my own ack into the data? Should i check to see if the port is in use before setting up a connection? Sorry for all the questions. This is all new to me but I enjoy this very much! ... Below already answered By Anton, Thanks It sounds like tcp uses its own packet numbering to ensure the packets end up in the right order on the other side. What if a packet is missed, are the subsequent packets thrown away? Or is this numbering and packet ordering, only for handling data that is broken out into multiple packets? TCP will automatically break the data into multiple packets if necessary right?

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  • How to know the type of an object in a list?

    - by nacho4d
    Hi, I want to know the type of object (or type) I have in my list so I wrote this: void **list; //list of references list = new void * [2]; Foo foo = Foo(); const char *not_table [] = {"tf", "ft", 0 }; list[0] = &foo; list[1] = not_table; if (dynamic_cast<LogicProcessor*>(list[0])) { //ERROR here ;( printf("Foo was found\n"); } if (dynamic_cast<char*> (list[0])) { //ERROR here ;( printf("char was found\n"); } but I get : error: cannot dynamic_cast '* list' (of type 'void*') to type 'class Foo*' (source is not a pointer to class) error: cannot dynamic_cast '* list' (of type 'void*') to type 'char*' (target is not pointer or reference to class) Why is this? what I am doing wrong here? Is dynamic_cast what I should use here? Thanks in advance EDIT: I know above code is much like plain C and surely sucks from the C++ point of view but is just I have the following situation and I was trying something before really implementing it: I have two arrays of length n but both arrays will never have an object at the same index. Hence, or I have array1[i]!=NULL or array2[i]!=NULL. This is obviously a waste of memory so I thought everything would be solved if I could have both kind of objects in a single array of length n. I am looking something like Cocoa's (Objective-C) NSArray where you don't care about the type of the object to be put in. Not knowing the type of the object is not a problem since you can use other method to get the class of a certain later. Is there something like it in c++ (preferably not third party C++ libraries) ? Thanks in advance ;)

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  • [Rails] Accessing error_messages on form_tag

    - by aaronrussell
    I have built a custom form for creating a joining model on a has_many :through relationship. The models look roughly like this: class Team has_many :team_members has_many :members, :through => :team_members end class Member has_many :team_members has_many :teams, :through => :team_members end class TeamMember belongs_to :team belongs_to :member # and this model has some validations too end The form I have built is for selecting which members should be in a team. I won't paste the form, but it uses the form_tag method and basically sends an array of hashes which contain a member_id and a squad_number. I then update the database with an action that looks roughly like this (simplified a bit, but you get the jist): @team.transaction do @team.team_members = params[:team_members].collect{|tm| @team.team_members.new(tm)} if @team.save redirect_to ... else render :action => :members end end Everything works great but I am validating the squad_number for uniqueness and numerically. So, when any of those validations fail, how do I get access to them in my view, and how do I ascertain which of the many members it has failed on?

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  • How do I display a sting, based on which id is set as selected?

    - by Cam
    I'd like to display a text string (to be positioned above ul) depending on which link is set to selected by the chgClass fuction. The ids for each display via an alert right now, but I can't seem to make them appear in "english". I know I can set up an array stating "id=text string" but when I do it seems to break the code I already have... <script type="text/javascript"> var Lst; function CngClass(obj){ if (typeof(obj)=='string') obj=document.getElementById(obj); if (Lst) Lst.className=''; obj.className='selected'; Lst=obj; alert(obj.id); } </script> </head> <body onload="CngClass('POSITION_WITHOUT_NOTIFY')"> <div class="slider"> <ul class="bar"> <li class="deny"><a onclick="CngClass(this);" id="POSITION_NOT_ALLOWED" href="#">Deny</a></li> <li class="askDeny"><a onclick="CngClass(this);" id="NOTIFY_POSITION_IF_GRANTED" href="#">Ask Deny</a></li> <li class="askAllow"><a onclick="CngClass(this);" id="NOTIFY_POSITION_IF_NO_RESPONSE" href="#">Ask Allow</a></li> <li class="notify"><a onclick="CngClass(this);" id="NOTIFY_POSITION" href="#">Notfiy</a></li> <li class="allow"><a onclick="CngClass(this);" id="POSITION_WITHOUT_NOTIFY" href="#">Allow</a></li> </ul> </div> </body> </html>

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  • Thread-Safe lazy instantiating using MEF

    - by Xaqron
    // Member Variable private static readonly object _syncLock = new object(); // Now inside a static method foreach (var lazyObject in plugins) { if ((string)lazyObject.Metadata["key"] = "something") { lock (_syncLock) { // It seems the `IsValueCreated` is not up-to-date if (!lazyObject.IsValueCreated) lazyObject.value.DoSomething(); } return lazyObject.value; } } Here I need synchronized access per loop. There are many threads iterating this loop and based on the key they are looking for, a lazy instance is created and returned. lazyObject should not be created more that one time. Although Lazy class is for doing so and despite of the used lock, under high threading I have more than one instance created (I track this with a Interlocked.Increment on a volatile static int and log it somewhere). The problem is I don't have access to definition of Lazy and MEF defines how the Lazy class create objects. I should notice the CompositionContainer has a thread-safe option in constructor which is already used. My questions: 1) Why the lock doesn't work ? 2) Should I use an array of locks instead of one lock for performance improvement ?

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  • Space between 2 vertices on a heightmap

    - by Sietse
    First off, I am sorry for the crazy title. I couldn't really think of something else. I am working on a hobby project, it's a infinite world generated with Perlin Noise, Java and LWJGL. But I am having a problem, it is kinda hard to explain, so I made a video: http://youtu.be/D_NUBJZ_5Kw Obviously the problem is the black spaces in between all the pieces of ground. I have no idea what is causing it. I already tried making all the values doubles instead of floats, but that didn't fix it. Here is a piece of code I am using: float height2, height = (float)getHeight(x, y); height2 = (float) ((getHeight(x-1, y+1) + height) / 2); vertexhelper.addVertexColorAndTexture(x, height2, y+1, r, g, b, a, 0f, 1f); height2 = (float) ((getHeight(x+1, y+1) + height) / 2); vertexhelper.addVertexColorAndTexture(x+1, height2, y+1, r, g, b, a, 1f, 1f); height2 = (float) ((getHeight(x+1, y-1) + height) / 2); vertexhelper.addVertexColorAndTexture(x+1, height2, y, r, g, b, a, 1f, 0f); height2 = (float) ((getHeight(x-1, y-1) + height) / 2); vertexhelper.addVertexColorAndTexture(x, height2, y, r, g, b, a, 0f, 0f); I loop through this at the initialization of a chunk with x-16 and y-16. vertexhelper is a class I made that just puts everything in a array. (I am using floats here, but that's after doing the maths, so that shouldn't be a problem) I highly appreciate you reading this.

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  • Create table class as a singleton

    - by Mark
    I got a class that I use as a table. This class got an array of 16 row classes. These row classes all have 6 double variables. The values of these rows are set once and never change. Would it be a good practice to make this table a singleton? The advantage is that it cost less memory, but the table will be called from multiple threads so I have to synchronize my code which way cause a bit slower application. However lookups in this table are probably a very small portion of the total code that is executed. EDIT: This is my code, are there better ways to do this or is this a good practice? Removed synchronized keyword according to recommendations in this question. final class HalfTimeTable { private HalfTimeRow[] table = new HalfTimeRow[16]; private static final HalfTimeTable instance = new HalfTimeTable(); private HalfTimeTable() { if (instance != null) { throw new IllegalStateException("Already instantiated"); } table[0] = new HalfTimeRow(4.0, 1.2599, 0.5050, 1.5, 1.7435, 0.1911); table[1] = new HalfTimeRow(8.0, 1.0000, 0.6514, 3.0, 1.3838, 0.4295); //etc } @Override @Deprecated public Object clone() throws CloneNotSupportedException { throw new CloneNotSupportedException(); } public static HalfTimeTable getInstance() { return instance; } public HalfTimeRow getRow(int rownumber) { return table[rownumber]; } }

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  • Are there concurrency problems when using -performSelector:withObject:afterDelay: ?

    - by mystify
    For example, I often use this: [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:someDelay]; Now, lets say I call this 10 times to perform at the exact same delay, like: [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; - (void)doSomethingAfterDelay:(id)someObject { /* access an array, read stuff, write stuff, do different things that would suffer in multithreaded environments .... all operations are nonatomic! */ } I have observed pretty strange behavior when doing things like this. For my understanding, this method schedules a timer to fire on the current thread, so in this case the main thread. But since it doesn't create new threads, it actually should not be possible to run into concurrency problems, right?

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  • Are there concurrency problems when using -performSelector:withObject:afterDelay: ?

    - by mystify
    For example, I often use this: [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:someDelay]; Now, lets say I call this 10 times to perform at the exact same delay, like: [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; [self performSelector:@selector(doSomethingAfterDelay:) withObject:someObject afterDelay:2.0]; - (void)doSomethingAfterDelay:(id)someObject { /* access an array, read stuff, write stuff, do different things that would suffer in multithreaded environments .... all operations are nonatomic! */ } I have observed pretty strange behavior when doing things like this. For my understanding, this method schedules a timer to fire on the current thread, so in this case the main thread. But since it doesn't create new threads, it actually should not be possible to run into concurrency problems, right?

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  • Why is it possible to enumerate a LinqToSql query after calling Dispose() on the DataContext?

    - by DanM
    I'm using the Repository Pattern with some LinqToSql objects. My repository objects all implement IDisposable, and the Dispose() method does only thing--calls Dispose() on the DataContext. Whenever I use a repository, I wrap it in a using person, like this: public IEnumerable<Person> SelectPersons() { using (var repository = _repositorySource.GetNew<Person>(dc => dc.Person)) { return repository.GetAll(); } } This method returns an IEnumerable<Person>, so if my understanding is correct, no querying of the database actually takes place until Enumerable<Person> is traversed (e.g., by converting it to a list or array or by using it in a foreach loop), as in this example: var persons = gateway.SelectPersons(); // Dispose() is fired here var personViewModels = ( from b in persons select new PersonViewModel { Id = b.Id, Name = b.Name, Age = b.Age, OrdersCount = b.Order.Count() }).ToList(); // executes queries In this example, Dispose() gets called immediately after setting persons, which is an IEnumerable<Person>, and that's the only time it gets called. So, a couple questions: How does this work? How can a disposed DataContext still query the database for results when I walk the IEnumerable<Person>? What does Dispose() actually do? I've heard that it is not necessary (e.g., see this question) to dispose of a DataContext, but my impression was that it's not a bad idea. Is there any reason not to dispose of it?

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  • Integration testing - can it be done right?

    - by Max
    I used TDD as a development style on some projects in the past two years, but I always get stuck on the same point: how can I test the integration of the various parts of my program? What I am currently doing is writing a testcase per class (this is my rule of thumb: a "unit" is a class, and each class has one or more testcases). I try to resolve dependencies by using mocks and stubs and this works really well as each class can be tested independently. After some coding, all important classes are tested. I then "wire" them together using an IoC container. And here I am stuck: How to test if the wiring was successfull and the objects interact the way I want? An example: Think of a web application. There is a controller class which takes an array of ids, uses a repository to fetch the records based on these ids and then iterates over the records and writes them as a string to an outfile. To make it simple, there would be three classes: Controller, Repository, OutfileWriter. Each of them is tested in isolation. What I would do in order to test the "real" application: making the http request (either manually or automated) with some ids from the database and then look in the filesystem if the file was written. Of course this process could be automated, but still: doesn´t that duplicate the test-logic? Is this what is called an "integration test"? In a book i recently read about Unit Testing it seemed to me that integration testing was more of an anti-pattern?

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  • Trigger alert when database entries are added, not when they are removed

    - by Jeremy
    I have a jQuery script running that makes a periodic AJAX call using the following code. var a = moment(); var dayOfMonth = a.format("MMM Do"); var timeSubmitted = a.format("h:mm a"); var count_cases = -1; var count_claimed = -1; setInterval(function(){ //check if new lead was added to the db $.ajax({ type : "POST", url : "inc/new_lead_alerts_process.php", dataType: 'json', cache: false, success : function(response){ $.getJSON("inc/new_lead_alerts_process.php", function(data) { if (count_cases != -1 && count_cases != data.count) { window.location = "new_lead_alerts.php?id="+data.id; } count_cases = data.count; }); } }); This is the PHP that runs with each call: $count = mysql_fetch_array(mysql_query("SELECT count(*) as count FROM leads")); $client_id = mysql_fetch_array(mysql_query("SELECT id, client_id FROM leads ORDER BY id DESC LIMIT 1")); echo json_encode(array("count" => $count['count'], "id" => $client_id['id'], "client_id" => $client_id['client_id'])); I need to change the code so that the alert only triggers when a new entry is added to the database, not when an existing entry is removed. As it stands, the alert fires on both events. Any help is greatly appreciated.

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  • SetMatrix() does not copy all values to HLSL

    - by Tili
    Hi, I want to use the contents of a vector of D3DXMatrices to my shader. m_pLightMatrices->SetMatrixArray(&currentLightMatrices[0].m[0][0],0,numLights); As we know the internals of a vector this poses no problems (as it is just a dynamic array). Now when I access this matrix in hlsl to fill up a struct I get this strange behavior: struct LightTest { float3 LightPos; float LightRange; float4 LightDiffuse; float3 LightAtt; }; float4x4 currentLight = gLights[0]; LightTest lt; lt.LightPos = currentLight._m00_m01_m02; //{0,0,0} lt.LightDiffuse = currentLight[1].rgba; //{0,0,0,0} lt.LightRange = currentLight._m03; //this gives me a value lt.LightAtt = currentLight[2].xyz; //{0,0,0} While debugging I see that my matrix is nicely filled with the variables I want. When I try to hardcode check what is in the struct I get all zero's, except the LightRange. As you can see I tried different methods of accessing the float4x4 but without any other results. Why oh why is hlsl not copying all my variables ?

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  • Quick question regarding MVC framework for a java game

    - by Jason
    I have a question regarding the use of the MVC framework for a blackjack game im writing in java. As I understand, my model would be a class that stores the state of the game, and more specifically, each players hand. Within the model class, I would have an array of listeners, which would be notified each time the game state changes (ie a player has drawn a new card). These listeners would be my viewer, which is the class that handles the display of the game. This class would implement the ActionListener interface, and each time the model changes, it would call/"notify" my viewer's actionPerformed method. My question is as follows: I intend to have two JPanels, each devoted to displaying the respective player's hand. As a player draws a new card, a new ImageIcon would be added to the panel. My question is how would the viewer class know what card has been added to the player's hand? I suppose I could store the player's hand before a notify event, and then upon the notification event, compare the new state with the old, to find out what has changed. I'm a complete novice here, so I could be completely wrong, but it seems a bit tedious to do this. Is there a more efficient/common way of detecting what has changed in the model between the before and after state? Another solution would be to redraw the entire panel each time the notification occurs? Would this be a better idea?

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