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  • Can I stop the dbml designer from adding a connection string to the dbml file?

    - by drs9222
    We have a custom function AppSettings.GetConnectionString() which is always called to determine the connection string that should be used. How this function works is unimportant to the discussion. It suffices to say that it returns a connection string and I have to use it. I want my LINQ to SQL DataContext to use this so I removed all connection string informatin from the dbml file and created a partial class with a default constructor like this: public partial class SampleDataContext { public SampleDataContext() : base(AppSettings.GetConnectionString()) { } } This works fine until I use the designer to drag and drop a table into the diagram. The act of dragging a table into the diagram will do several unwanted things: A settings file will be created A app.config file will be created My dbml file will have the connection string embedded in it All of this is done before I even save the file! When I save the diagram the designer file is recreated and it will contain its own default constructor which uses the wrong connection string. Of course this means my DataContext now has two default constructors and I can't build anymore! I can undo all of these bad things but it is annoying. I have to manually remove the connection string and the new files after each change! Is there anyway I can stop the designer from making these changes without asking? EDIT The requirement to use the AppSettings.GetConnectionString() method was imposed on me rather late in the game. I used to use something very similar to what it generates for me. There are quite a few places that call the default constructor. I am aware that change them all to create the data context in another way (using a different constructor, static method, factory, ect..). That kind of change would only be slightly annoying since it would only have to be done once. However, I feel, that it is sidestepping the real issue. The dbml file and configuration files would still contain an incorrect, if unused, connection string which at best could confuse other developers.

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  • AVAudioPlayer not unloading cached memory after each new allocation

    - by Rob
    I am seeing in Instruments that when I play a sound via the standard "AddMusic" example method that Apple provides, it allocates 32kb of memory via the prepareToPlay call (which references the AudioToolBox framework's Cache_DataSource::ReadBytes function) each time a new player is allocated (i.e. each time a different sound is played). However, that cached data never gets released. This obviously poses a huge problem if it doesn't get released and you have a lot of sound files to play, since it tends to keep allocating memory and eventually crashes if you have enough unique sound files (which I unfortunately do). Have any of you run across this or what am I doing wrong in my code? I've had this issue for a while now and it's really bugging me since my code is verbatim of what Apple's is (I think). How I call the function: - (void)playOnce:(NSString *)aSound { // Gets the file system path to the sound to play. NSString *soundFilePath = [[NSBundle mainBundle] pathForResource:aSound ofType:@"caf"]; // Converts the sound's file path to an NSURL object NSURL *soundURL = [[NSURL alloc] initFileURLWithPath: soundFilePath]; self.soundFileURL = soundURL; [soundURL release]; AVAudioPlayer * newAudio=[[AVAudioPlayer alloc] initWithContentsOfURL: soundFileURL error:nil]; self.theAudio = newAudio; // automatically retain audio and dealloc old file if new m4a file is loaded [newAudio release]; // release the audio safely // this is where the prior cached data never gets released [theAudio prepareToPlay]; // set it up and play [theAudio setNumberOfLoops:0]; [theAudio setVolume: volumeLevel]; [theAudio setDelegate: self]; [theAudio play]; } and then theAudio gets released in the dealloc method of course.

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  • Duplicating custom nodes in JavaFX

    - by Elazar Leibovich
    As far as I understand, duplicating nodes in JavaFX should be done with the Duplicator.duplicate function. It works fine when duplicating nodes whose types are included in JavaFX library, for example def dup = Duplicator.duplicate(Rectangle{x:30 y:30 width:100 height:100}); dup.translateX = 10; insert dup into content; would insert a black rectangle to the scene. However if I define a new class in the following way: class MyRect extends Rectangle {} Or class MyRect extends CustomNode { override function create() {Rectangle{x:30 y:30 width:10 height:10}} } It gives me the following runtime error Type 'javafxapplication1.NumberGrid$MyRect' not found. Where of course javafxapplication1.NumberGrid are the package and file the MyRect class is in. This guy at Sun's forums had the same problem, but I don't see any answer in there. Or maybe I'm doing that the wrong way, and there's a better approach for duplicating custom nodes? update: Trying to duplicate Group worked, but trying to duplicate Stack yields the same error. According to the documentation, it's supposed to support all types supported in FXD including Node, but maybe it supports only some of Node's descendants?

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  • Simplest PHP Routing framework .. ?

    - by David
    I'm looking for the simplest implementation of a routing framework in PHP, in a typical PHP environment (Running on Apache, or maybe nginx) .. It's the implementation itself I'm mostly interested in, and how you'd accomplish it. I'm thinking it should handle URL's, with the minimal rewriting possible, (is it really a good idea, to have the same entrypoint for all dynamic requests?!), and it should not mess with the querystring, so I should still be able to fetch GET params with $_GET['var'] as you'd usually do.. So far I have only come across .htaccess solutions that puts everything through an index.php, which is sort of okay. Not sure if there are other ways of doing it. How would you "attach" what URL's fit to what controllers, and the relation between them? I've seen different styles. One huge array, with regular expressions and other stuff to contain the mapping. The one I think I like the best is where each controller declares what map it has, and thereby, you won't have one huge "global" map, but a lot of small ones, each neatly separated. So you'd have something like: class Root { public $map = array( 'startpage' => 'ControllerStartPage' ); } class ControllerStartPage { public $map = array( 'welcome' => 'WelcomeControllerPage' ); } // Etc ... Where: 'http://myapp/' // maps to the Root class 'http://myapp/startpage' // maps to the ControllerStartPage class 'http://myapp/startpage/welcome' // maps to the WelcomeControllerPage class 'http://myapp/startpage/?hello=world' // Should of course have $_GET['hello'] == 'world' What do you think? Do you use anything yourself, or have any ideas? I'm not interested in huge frameworks already solving this problem, but the smallest possible implementation you could think of. I'm having a hard time coming up with a solution satisfying enough, for my own taste. There must be something pleasing out there that handles a sane bootstrapping process of a PHP application without trying to pull a big magic hat over your head, and force you to use "their way", or the highway! ;)

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  • How can I bind a javascript dialog using Knockout?

    - by Brian
    I've got a list of data in an observableArray and I want to show it in a javascript dialog window (I'm using jQuery.blockUI if it matters). Unfortunately the dialog seems to come unbound after the page is loaded. The dialog initializes correctly (the data is displayed), but it isn't updating with changes. There are no Javascript errors and I've moved the binding to after the dialog is generated and added to the document (no effect). I've also tried calling ko.applyBinding on the main div that makes up the dialog but that, for some reason, causes part of the main page to hide (the DOM is there, but they are hidden). EDIT: I've created a project on jsfiddle that reproduces the problem. The main culprit seems to be wrapping the content of the dialog in a div. If I show the content directly it seems to work (of course I can't do that, the wrappers provide a common style for our dialogs). I'm recovering from the flu and could easily be missing something obvious, but I've been trying all day and nothing is coming to me. Any ideas?

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  • Counting computers for each lab

    - by Irvin
    Alright I have a problem with having to count PCs, and Macs from different labs. In each lab I need to display how many PC and Macs there is available. The data is coming from a SQL server, right am trying sub queries and the use of union, this the closest I can get to what I need. The query below shows me the number of PCs, and Macs in two different columns, but of course, the PCs will be in one row and the Macs on another right below it. Having the lab come up twice. EX: LabName -- PC / MAC Lab1 -- 5 / 0 Lab1 -- 0 / 2 Query SELECT Labs.LabName, COUNT(*),0 AS Mac FROM HardWare INNER JOIN Labs ON HardWare.LabID = Labs.LabID WHERE ComputerStatus = 'AVAILABLE' GROUP BY Labs.LabName UNION SELECT Labs.LabName, COUNT(*), (SELECT COUNT(Manufacturer)) AS Mac FROM HardWare INNER JOIN Labs ON HardWare.LabID = Labs.LabID WHERE ComputerStatus = 'AVAILABLE' AND Manufacturer = 'Apple' GROUP BY Labs.LabName ORDER BY Labs.LabName So is there any way to get them together in one row as in Lab1 -- 5 / 2 or is there a different way to write the query? anything will be a big help, am pretty much stuck here. Cheers

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  • Team Build Reports as "Failed" Even Though All Targets Succeeded

    - by benjy
    Hi, I've written a custom MSBuild script to be used with Team Build, as I am storing PHP in TFS and of course it isn't compiled. My custom script calls the CoreGet target to get the latest version of the files, and the copies them, ZIPs, them, and FTPs the ZIP archive to a testing server. All of that is working fine. The problem I am having is that despite the build succeeding - see the output in BuildLog.txt - Done executing task "BuildStep". Done building target "FTP" in project "TFSBuild.proj". Done executing task "CallTarget". Done building target "EndToEndIteration" in project "TFSBuild.proj". Done Building Project "C:\Documents and Settings\tfsservice\Local Settings\Temp\Code\PHP\BuildType\TFSBuild.proj" (EndToEndIteration target(s)). Build succeeded. 0 Warning(s) 0 Error(s) the build still reports as having failed. The log from Visual Studio looks like so: Anyone know how I can make it report as having succeeded? Thanks very much in advance, Benjy P.S.: Please let me know if anyone would find having the whole build script helpful. Thanks!

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  • A question about writing a background/automatic/silent downloader/installer for an app in C#.

    - by Mike Webb
    Background: I have a main application that needs to be able to go to the web and download DLL files associated with it (ones that we write, located on our server). It really needs to be able to download these DLL files to the application folder in "C:\Program Files\". In the past I have used System.Net.WebClient to download whatever files I wanted from the web. The Issue I have had a lot of trouble downloading data in the past and saving to files on a user's hard drive. I get many reports of users saying that this does not work and it is generally because of user rights issues in the program. In the cases where it was an issue with program user rights every user could go to the exact file location on the web, download it, and then save it to the right place manually. I want this to work like all the other programs I have seen download/install in this fassion (i.e. Firefox Pluign Updates, Flash Player, JAVA, Adobe Reader, etc). All of these work without a hitch. The Question Is there some code I need to use to give my downloader program special rights to the Program Files folder? Can I even do this? Is there a better class or library that I should use? Is there a different approach to downloading files I should take, such as using threads or something else to download data? Any help here is appreciated. I want to try to stay away from third-party apps/libraries if at all possible, other than Microsoft of course, due to licensing issues, but still send any suggestions my way. Again, other programs seem to have the rights issues and download capability figured out. I want this same capability.

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  • IPhone SDK help with minigame

    - by Harry
    right basically what ive got is an app which is a ball and bat and its how many bounces you can achieve, it works alright but there is one problem, when the ball hits the side of the bat it throws it off course and its like the frame of the ball is bouncing in the frame of the bat, Here is my code in my mainview.m #import "MainView.h" #define kGameStateRunning 1 @implementation MainView @synthesize paddle, ball; - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { UITouch *touch = [[event allTouches] anyObject]; CGPoint location = [touch locationInView:touch.view]; CGPoint xLocation = CGPointMake(location.x,paddle.center.y); paddle.center = xLocation; } -(IBAction) play { pos = CGPointMake(14.0,7.0); [NSTimer scheduledTimerWithTimeInterval:0.05 target:self selector:@selector(onTimer) userInfo:nil repeats:YES]; } -(void) onTimer { ball.center = CGPointMake(ball.center.x+pos.x,ball.center.y+pos.y); if(ball.center.x > 320 || ball.center.x < 0) pos.x = -pos.x; if(ball.center.y > 460 || ball.center.y < 0) pos.y = -pos.y; [self checkCollision]; } -(void) checkCollision { if(CGRectIntersectsRect(ball.frame,paddle.frame)) { pos.y = -pos.y; } } @end can anyone work out the problem here? Thanks Harry

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  • Algorithm for scoring user activity

    - by ManBugra
    I have an application where users can: Write reviews about products Add comments to products Up / Down vote reviews Up / Down vote comments Every Up/Down vote is recorded in a db table. What i want to do now is to create a ranking of the most active users in the last 4 weeks. Of course good reviews should be weighted more than good comments. But also e.g. 10 good comments should be weighted more than just one good review. Example: // reviews created in recent 4 weeks //format: [ upVoteCount, downVoteCount ] var reviews = [ [120,23], [32,12], [12,0], [23,45] ]; // comments created in recent 4 weeks // format: [ upVoteCount, downVoteCount ] var comments = [ [1,2], [322,1], [0,0], [0,45] ]; // create weight vector // format: [ reviewWeight, commentsWeight ] var weight = [0.60, 0.40]; // signature: activties..., activityWeight var userActivityScore = score(reviews, comments, weight); ... update user table ... List<Users> users = "from users u order by u.userActivityScore desc"; How would a fair scoring function look like? How could an implementation of the score() function look like? How to add a weight g to the function so that reviews are weighted heavier? How would such a function look like if, for example, votes for pictures would be added?

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  • Multiple consecutive alerts in Java ME

    - by Casebash
    According to the documentation, Display.setCurrent doesn't work if the current displayable is an alert. Does anyone know how to work around this so that we can go from one alert to another? I am using CLDC 1.0 and MIDP 2.0. My attempt The spec does allow us to edit an alert while it is on screen, but some Nokia phones don't handle it well at all. So I am now trying to go from the alert to a canvas, then back to the alert. Of course I don't want the user to interact with the previous canvas, so it seems that I am forced to create a new blank canvas. As a sidenote, this has the slight disadvantage of looking worse on phones which still have the previous screen when an alert is shown. The bigger problem is how to transition from the blank canvas back to an alert once the canvas is loaded. Testing on the Motorola emulator revealed that showNotify is not called after returning from an alert to the previous screen. I guess I could create the next alert in the paint method, but this seems like a ugly hack.

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  • Dynamic ExpandableListView

    - by JLB
    Can anyone tell me how I can Dynamically add groups & children to an ExpandableListView. The purpose is to create a type of task list that I can add new items/groups to. I can populate the view with pre-filled arrays but of course can't add to them to populate the list further. The other method i tried was using the SimpleExpandableListAdapter. Using this i am able to add groups from a List but when it comes to adding children i can only add 1 item per group. public List<Map<String, String>> groupData = new ArrayList<Map<String, String>>(); public List<List<Map<String, String>>> childData = new ArrayList<List<Map<String, String>>>(); public void addGroup(String group) { Map curGroupMap = new HashMap(); groupData.add(curGroupMap); curGroupMap.put(NAME, group); //Add an empty child or else the app will crash when group is expanded. List<Map<String, String>> children = new ArrayList<Map<String, String>>(); Map<String, String> curChildMap = new HashMap<String, String>(); children.add(curChildMap); curChildMap.put(NAME, "EMPTY"); childData.add(children); updateAdapter(); } public void addChild(String child) { List children = new ArrayList(); Map curChildMap = new HashMap(); children.add(curChildMap); curChildMap.put(NAME, child); curChildMap.put(IS_EVEN, "This child is even"); childData.add(activeGroup, children); updateAdapter(); }

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  • ASP.Net MVC 2 - How to set up a Cancel button with client side navigation

    - by arame3333
    Thanks to a previous question I found a useful link on multiple buttons. http://weblogs.asp.net/dfindley/archive/2009/05/31/asp-net-mvc-multiple-buttons-in-the-same-form.aspx What I want to do is have a cancel button on my page, similar to this; <button name="button" type="button" onclick="document.location.href=$('#cancelUrl').attr('href')">Cancel</button> <a id="cancelUrl" href="<%: Url.Action("Index", "Home") %>" style="display:none;"></a> However although this code works, I really want to go back to the previous page. For Web Forms I could use the javascript Back() or Go(-1) functions, but they relied on postbacks. I could of course hard code the previous page and controller as I have done above. However I am struggling to find links that explain to me how Url.Action works. Because if I do this, I also need to include an index parameter, and I am not clear how the syntax works for that. It seems odd the amount of coding to do this. Out of curiosity, I am also wondering how you TDD client side code like this.

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  • How can I create objects based on dump file memory in a WinDbg extension?

    - by pj4533
    I work on a large application, and frequently use WinDbg to diagnose issues based on a DMP file from a customer. I have written a few small extensions for WinDbg that have proved very useful for pulling bits of information out of DMP files. In my extension code I find myself dereferencing c++ class objects in the same way, over and over, by hand. For example: Address = GetExpression("somemodule!somesymbol"); ReadMemory(Address, &addressOfPtr, sizeof(addressOfPtr), &cb); // get the actual address ReadMemory(addressOfObj, &addressOfObj, sizeof(addressOfObj), &cb); ULONG offset; ULONG addressOfField; GetFieldOffset("somemodule!somesymbolclass", "somefield", &offset); ReadMemory(addressOfObj+offset, &addressOfField, sizeof(addressOfField), &cb); That works well, but as I have written more extensions, with greater functionality (and accessing more complicated objects in our applications DMP files), I have longed for a better solution. I have access to the source of our own application of course, so I figure there should be a way to copy an object out of a DMP file and use that memory to create an actual object in the debugger extension that I can call functions on (by linking in dlls from our application). This would save me the trouble of pulling things out of the DMP by hand. Is this even possible? I tried obvious things like creating a new object in the extension, then overwriting it with a big ReadMemory directly from the DMP file. This seemed to put the data in the right fields, but freaked out when I tried to call a function. I figure I am missing something...maybe c++ pulls some vtable funky-ness that I don't know about? My code looks similar to this: SomeClass* thisClass = SomeClass::New(); ReadMemory(addressOfObj, &(*thisClass), sizeof(*thisClass), &cb);

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  • substitution cypher with different alphabet length

    - by seanizer
    I would like to implement a simple substitution cypher to mask private ids in URLs I know how my IDs will look like (combination of upperchase ascii, digits and underscore), and they will be rather long, as they are composed keys. I would like to use a longer alphabet to shorten the resulting codes (I'd like to use upper and lower case ascii letters, digits and nothing else). So my incoming alphabet would be [A-Z0-9_] (37 chars) and my outgoing alphabet would be [A-Za-z0-9] (62 chars) so a compression of almost 50% would be available. let's say my URLs look like this: /my/page/GFZHFFFZFZTFZTF_24_F34 and I want them to look like this instead: /my/page/Ft32zfegZFV5 Obviously both arrays would be shuffled to bring some random order in. This does not have to be secure. if someone figures it out: fine, but I don't want the scheme to be obvious. My desired solution would be to convert the string to an integer representation of radix 37, convert the radix to 62 and use the second alphabet to write out that number. is there any sample code available that does something similar? Integer.parseInt ( http://java.sun.com/javase/6/docs/api/java/lang/Integer.html#parseInt%28java.lang.String,%20int%29 ) has some similar logic, but it is hard-coded to use standard digit behavior Any hints? I am using java to implement this but code or pseudo-code in any other language is of course also helpful

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  • OO Objective-C design with XML parsing

    - by brainfsck
    Hi, I need to parse an XML record that represents a QuizQuestion. The "type" attribute tells the type of question. I then need to create an appropriate subclass of QuizQuestion based on the question type. The following code works ([auto]release statements omitted for clarity): QuizQuestion *question = [[QuizQuestion alloc] initWithXMLString:xml]; if( [ [question type] isEqualToString:@"multipleChoiceQuestion"] ) { [myQuestions addObject:[[MultipleChoiceQuizQuestion alloc] initWithXMLString:xml]; } //QuizQuestion.m -(id)initWithXMLString:(NSString*)xml { self.type = ...// parse "type" attribute from xml // parse the rest of the xml } //MultipleChoiceQuizQuestion.m -(id)initWithXMLString:(NSString*)xml { if( self= [super initWithXMLString:xml] ) { // multiple-choice stuff } } Of course, this means that the XML is parsed twice: once to find out the type of QuizQuestion, and once when the appropriate QuizQuestion is initialized. To prevent parsing the XML twice, I tried the following approach: // MultipleChoiceQuizQuestion.m -(id)initWithQuizRecord:(QuizQuestion*)record { self=record; // record has already parsed the "type" and other parameters // multiple-choice stuff } However, this fails due to the "self=record" assignment; whenever the MultipleChoiceQuizQuestion tries to call an instance-method, it tries to call the method on the QuizQuestion class instead. Can someone tell me the correct approach for parsing XML into the appropriate subclass when the parent class needs to be initialized to know which subclass is appropriate?

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  • div stacking/layout with css or javascript

    - by liz
    so i have 4 divs (i actually have many more but this will simplify the question). i want to display them in two columns. the 4 divs vary in height. the number of actual divs in the end will vary. so if i have this <div id="1" style="height: 200px" class="inline">some content here</div> <div id="2" style="height: 600px" class="inline">some content here</div> <div id="3" style="height: 300px" class="inline">some content here</div> <div id="4" style="height: 200px" class="inline">some content here</div> with styling thus .inline { display: inline-block; vertical-align: top; width: 48%;} so #1 would go left and then #2 would shove up beside it to the right, great, but the #3 will not slide up the 400px to fit nicely below #1. (of course)... it goes on the left side but at 600px from the top clearing the bottom of #2. etc... how would i get the divs to slide up into the empty spaces, is it possible with css? jquery maybe? i know i could write column divs to mark it up, but since the number of divs constantly change and the heights vary according to content. It would be nice to just get rid of the space since we dont really care about the order. any thoughts?

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  • How can I display multiple django modelformset forms together?

    - by JT
    I have a problem with needing to provide multiple model backed forms on the same page. I understand how to do this with single forms, i.e. just create both the forms call them something different then use the appropriate names in the template. Now how exactly do you expand that solution to work with modelformsets? The wrinkle, of course, is that each 'form' must be rendered together in the appropriate fieldset. For example I want my template to produce something like this: <fieldset> <label for="id_base-0-desc">Home Base Description:</label> <input id="id_base-0-desc" type="text" name="base-0-desc" maxlength="100" /> <label for="id_likes-0-icecream">Want ice cream?</label> <input type="checkbox" name="likes-0-icecream" id="id_likes-0-icecream" /> </fieldset> <fieldset> <label for="id_base-1-desc">Home Base Description:</label> <input id="id_base-1-desc" type="text" name="base-1-desc" maxlength="100" /> <label for="id_likes-1-icecream">Want ice cream?</label> <input type="checkbox" name="likes-1-icecream" id="id_likes-1-icecream" /> </fieldset> I am using a loop like this to process the results for base_form, likes_form in map(None, base_forms, likes_forms): which works as I'd expect (I'm using map because the # of forms can be different). The problem is that I can't figure out a way to do the same thing with the templating engine. The system does work if I layout all the base models together then all the likes models after wards, but it doesn't meet the layout requirements.

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  • Choose a XML node in SQL Server based on max value of a child element

    - by Jay
    I am trying to select from SQL Server 2005 XML datatype some values based on the max data that is located in a child node. I have multiple rows with XML similar to the following stored in a field in SQL Server: <user> <name>Joe</name> <token> <id>ABC123</id> <endDate>2013-06-16 18:48:50.111</endDate> </token> <token> <id>XYX456</id> <endDate>2014-01-01 18:48:50.111</endDate> </token> </user> I want to perform a select from this XML column where it determines the max date within the token element and would return the datarows similar to the result below for each record: Joe XYZ456 2014-01-01 18:48:50.111 I have tried to find a max function for xpath that would all me to select the correct token element but I couldn't find one that would work. I also tried to use the SQL MAX function but I wasn't able to get it working with that method either. If I only have a single token it of course works fine but when I have more than one I get a NULL, most likely because the query doesn't know which date to pull. I was hoping there would be a way to specify a where clause [max(endDate)] on the token element but haven't found a way to do that. Here is an example of the one that works when I only have a single token: SELECT XMLCOL.query('user/name').value('.','NVARCHAR(20)') as name XMLCOL.query('user/token/id').value('.','NVARCHAR(20)') as id XMLCOL.query('user/token/endDate').value(,'xs:datetime(.)','DATETIME') as endDate FROM MYTABLE

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  • using compareTo in Binary Search Tree program

    - by Scott Rogener
    I've been working on this program for a few days now and I've implemented a few of the primary methods in my BinarySearchTree class such as insert and delete. Insert seemed to be working fine, but once I try to delete I kept getting errors. So after playing around with the code I wanted to test my compareTo methods. I created two new nodes and tried to compare them and I get this error: Exception in thread "main" java.lang.ClassCastException: TreeNode cannot be cast to java.lang.Integer at java.lang.Integer.compareTo(Unknown Source) at TreeNode.compareTo(TreeNode.java:16) at BinarySearchTree.myComparision(BinarySearchTree.java:177) at main.main(main.java:14) Here is my class for creating the nodes: public class TreeNode<T> implements Comparable { protected TreeNode<T> left, right; protected Object element; public TreeNode(Object obj) { element=obj; left=null; right=null; } public int compareTo(Object node) { return ((Comparable) this.element).compareTo(node); } } Am I doing the compareTo method all wrong? I would like to create trees that can handle integers and strings (seperatly of course)

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  • Groovy / Scala / Java under the hood

    - by Jack
    I used Java for like 6-7 years, then some months ago I discovered Groovy and started to save a lot of typing.. then I wondered how certain things worked under the hood (because groovy performance is really poor) and understood that to give you dynamic typing every Groovy object is a MetaClass object that handles all the things that the JVM couldn't handle by itself. Of course this introduces a layer in the middle between what you write and what you execute that slows down everything. Then somedays ago I started getting some infos about Scala. How these two languages compare in their byte code translations? How much things they add to the normal structure that it would be obtained by plain Java code? I mean, Scala is static typed so wrapper of Java classes should be lighter, since many things are checked during compile time but I'm not sure about the real differences of what's going inside. (I'm not talking about the functional aspect of Scala compared to the other ones, that's a different thing) Can someone enlighten me? From WizardOfOdds it seems like that the only way to get less typing and same performance would be to write an intermediate translator that translates something in Java code (letting javac compile it) without alterating how things are executed, just adding synctatic sugar withour caring about other fallbacks of the language itself.

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  • Zipping with padding in Haskell

    - by Travis Brown
    A couple of times I've found myself wanting a zip in Haskell that adds padding to the shorter list instead of truncating the longer one. This is easy enough to write. (Monoid works for me here, but you could also just pass in the elements that you want to use for padding.) zipPad :: (Monoid a, Monoid b) => [a] -> [b] -> [(a, b)] zipPad xs [] = zip xs (repeat mempty) zipPad [] ys = zip (repeat mempty) ys zipPad (x:xs) (y:ys) = (x, y) : zipPad xs ys This approach gets ugly when trying to define zipPad3. I typed up the following and then realized that of course it doesn't work: zipPad3 :: (Monoid a, Monoid b, Monoid c) => [a] -> [b] -> [c] -> [(a, b, c)] zipPad3 xs [] [] = zip3 xs (repeat mempty) (repeat mempty) zipPad3 [] ys [] = zip3 (repeat mempty) ys (repeat mempty) zipPad3 [] [] zs = zip3 (repeat mempty) (repeat mempty) zs zipPad3 xs ys [] = zip3 xs ys (repeat mempty) zipPad3 xs [] zs = zip3 xs (repeat mempty) zs zipPad3 [] ys zs = zip3 (repeat mempty) ys zs zipPad3 (x:xs) (y:ys) (z:zs) = (x, y, z) : zipPad3 xs ys zs At this point I cheated and just used length to pick the longest list and pad the others. Am I overlooking a more elegant way to do this, or is something like zipPad3 already defined somewhere?

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  • gcc, strict-aliasing, and horror stories

    - by Joseph Quinsey
    In http://stackoverflow.com/questions/2906365/gcc-strict-aliasing-and-casting-through-a-union I asked whether anyone had encountered problems with union punning through pointers. So far, the answer seems to be No. This question is broader: do you have any horror stories about gcc and strict-aliasing? Background: Quoting from AndreyT's answer in http://stackoverflow.com/questions/2771023/c99-strict-aliasing-rules-in-c-gcc/2771041#2771041: "Strict aliasing rules are rooted in parts of the standard that were present in C and C++ since the beginning of [standardized] times. The clause that prohibits accessing object of one type through a lvalue of another type is present in C89/90 (6.3) as well as in C++98 (3.10/15). ... It is just that not all compilers wanted (or dared) to enforce it or rely on it." Well, gcc is now daring to do so, with its -fstrict-aliasing switch. And this has caused some problems. See, for example, the excellent article http://davmac.wordpress.com/2009/10/ about a Mysql bug, and the equally excellent discussion in http://cellperformance.beyond3d.com/articles/2006/06/understanding-strict-aliasing.html. Some other less-relevant links: http://stackoverflow.com/questions/1225741/performance-impact-of-fno-strict-aliasing http://stackoverflow.com/questions/754929/strict-aliasing http://stackoverflow.com/questions/262379/when-is-char-safe-for-strict-pointer-aliasing http://stackoverflow.com/questions/725138/how-to-detect-strict-aliasing-at-compile-time So to repeat, do you have a horror story of your own? Problems not indicated by -Wstrict-aliasing would, of course, be preferred. And other C compilers are also welcome.

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  • Elegant way of parsing Data files for Simulation

    - by sc_ray
    I am working on this project where I need to read in a lot of data from .dat files and use the data to perform simulations. The data in my .dat file looks as follows: DeviceID InteractingDeviceID InteractionStartTime InteractionEndTime 1 2 1101 1105 1,2 1101 and 1105 are tab delimited and it means Device 1 interacted with Device 2 at 1101 ms and ended the interaction at 1105ms. I have a trace data sets that compile thousands of such interactions and my job is to analyze these interactions. The first step is to parse the file. The language of choice is C++. The approach I was thinking of taking was to read the file, for every line that's read create a Device Object. This Device object will contain the property DeviceId and an array/vector of structs, that will contain a list of all the devices the given DeviceId interacted with over the course of the simulation.The struct will contain the Interacting Device Id, Interaction Start Time and Interaction End Time. I have a two fold question here: Is my approach correct? If I am on the right track, how do I rapidly parse these tab delimited data files and create Device objects without excessive memory overhead using C++? A push in the right direction will be much appreciated. Thanks

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  • How do I dispatch to a method based on a parameter's runtime type in C# < 4?

    - by Evan Barkley
    I have an object o which guaranteed at runtime to be one of three types A, B, or C, all of which implement a common interface I. I can control I, but not A, B, or C. (Thus I could use an empty marker interface, or somehow take advantage of the similarities in the types by using the interface, but I can't add new methods or change existing ones in the types.) I also have a series of methods MethodA, MethodB, and MethodC. The runtime type of o is looked up and is then used as a parameter to these methods. public void MethodA(A a) { ... } public void MethodB(B b) { ... } public void MethodC(C c) { ... } Using this strategy, right now a check has to be performed on the type of o to determine which method should be invoked. Instead, I would like to simply have three overloaded methods: public void Method(A a) { ... } // these are all overloads of each other public void Method(B b) { ... } public void Method(C c) { ... } Now I'm letting C# do the dispatch instead of doing it manually myself. Can this be done? The naive straightforward approach doesn't work, of course: Cannot resolve method 'Method(object)'. Candidates are: void Method(A) void Method(B) void Method(C)

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