Search Results

Search found 43540 results on 1742 pages for 'method missing'.

Page 327/1742 | < Previous Page | 323 324 325 326 327 328 329 330 331 332 333 334  | Next Page >

  • Andengine put bullet to pull, when it leaves screen

    - by Ashot
    i'm creating a bullet with physics body. Bullet class (extends Sprite class) has die() method, which unregister physics connector, hide sprite and put it in pull public void die() { Log.d("bulletDie", "See you in hell!"); if (this.isVisible()) { this.setVisible(false); mPhysicsWorld.unregisterPhysicsConnector(physicsConnector); physicsConnector.setUpdatePosition(false); body.setActive(false); this.setIgnoreUpdate(true); bulletsPool.recyclePoolItem(this); } } in onUpdate method of PhysicsConnector i executes die method, when sprite leaves screen physicsConnector = new PhysicsConnector(this,body,true,false) { @Override public void onUpdate(final float pSecondsElapsed) { super.onUpdate(pSecondsElapsed); if (!camera.isRectangularShapeVisible(_bullet)) { Log.d("bulletDie","Dead?"); _bullet.die(); } } }; it works as i expected, but _bullet.die() executes TWICE. what i`m doing wrong and is it right way to hide sprites? here is full code of Bullet class (it is inner class of class that represents player) private class Bullet extends Sprite implements PhysicsConstants { private final Body body; private final PhysicsConnector physicsConnector; private final Bullet _bullet; private int id; public Bullet(float x, float y, ITextureRegion texture, VertexBufferObjectManager vertexBufferObjectManager) { super(x,y,texture,vertexBufferObjectManager); _bullet = this; id = bulletId++; body = PhysicsFactory.createCircleBody(mPhysicsWorld, this, BodyDef.BodyType.DynamicBody, bulletFixture); physicsConnector = new PhysicsConnector(this,body,true,false) { @Override public void onUpdate(final float pSecondsElapsed) { super.onUpdate(pSecondsElapsed); if (!camera.isRectangularShapeVisible(_bullet)) { Log.d("bulletDie","Dead?"); Log.d("bulletDie",id+""); _bullet.die(); } } }; mPhysicsWorld.registerPhysicsConnector(physicsConnector); $this.getParent().attachChild(this); } public void reset() { final float angle = canon.getRotation(); final float x = (float) ((Math.cos(MathUtils.degToRad(angle))*radius) + centerX) / PIXEL_TO_METER_RATIO_DEFAULT; final float y = (float) ((Math.sin(MathUtils.degToRad(angle))*radius) + centerY) / PIXEL_TO_METER_RATIO_DEFAULT; this.setVisible(true); this.setIgnoreUpdate(false); body.setActive(true); mPhysicsWorld.registerPhysicsConnector(physicsConnector); body.setTransform(new Vector2(x,y),0); } public Body getBody() { return body; } public void setLinearVelocity(Vector2 velocity) { body.setLinearVelocity(velocity); } public void die() { Log.d("bulletDie", "See you in hell!"); if (this.isVisible()) { this.setVisible(false); mPhysicsWorld.unregisterPhysicsConnector(physicsConnector); physicsConnector.setUpdatePosition(false); body.setActive(false); this.setIgnoreUpdate(true); bulletsPool.recyclePoolItem(this); } } }

    Read the article

  • A few questions about integrating AudioKinetic Wwise and Unity

    - by SaldaVonSchwartz
    I'm new to Wwise and to using it with Unity, and though I have gotten the integration to work, I'm still dealing with some loose ends and have a few questions: (I'm on Unity 4.3 as of now but I think it shouldn't make any difference) The base path: The Wwise documentation implies you set this in the AkGlobalSoundEngineInitializer basePath public ivar, which is exposed to the editor. However, I found that this variable is not really used. Instead, the path is hardcoded to /Audio/GeneratedSoundBanks in AkBankPath. I had to modify both scripts to actually look in the path that I set in the editor property. What's the deal with this? Just sloppyness or am I missing something? Also about paths: since I'm on Mac, I'm using Unity natively under OS X and in tadem, the Wwise authoring tool via VMWare and I share the OS X Unity project folder so I can generate the soundbanks into the assets folder. However, the authoring tool (downloaded the latest one for Windows) doesn't automatically generate any "platform-specific" subfolders for my wwise files. That is, again, the Unity integration scripts assume the path to be /Audio/GeneratedSoundBanks/<my-platform>/ which in my case would be Mac (I set the authoring tool to generate for Mac). The documentation says wwise will automatically generate the platform-specific folders but it just dumps all the stuff in GeneratedSoundBanks. Am I missing some setting? cause right now I just manually create the /Mac folder. The C# methods AkSoundEngine.PostEvent and AkSoundEngine.LoadBank for instance, have a few overloads, including ones where I can refer to the soundbanks or events by their ID. However, if I try to use these, for instance: AkSoundEngine.LoadBank(, AkSoundEngine.AK_DEFAULT_POOL_ID) where the int I got from the .h header, I get Ak_Fail. If I use the overloads that reference the objects by string name then it works. What gives? Converting the ID header to C#: The integration comes with a C# script that seems to fork a process to call Python in turn to covert the C++ header into a C# script. This always fails unless I manually execute the Python script myself from outside Unity. Might be a permissions thing, but has anyone experienced this? The Profiler: I set up the Unity player to run in the background and am using the "Profile" version of the plugin. However, when I start the Unity OS X standalone app, the profiler in VMWare does not see it. This I'm thinking might just be that I'm trying to see a running instance of the sound engine inside an OS X binary from a Windows virtual machine. But I'm just wondering if anyone has gotten the Windows profiler to see an OS X Unity binary. Different versions of the integration plugin: It's not clear to me from the documentation whether I have to manually (or write a script to do it) remove the "Profile" version and install the "Release" version when I'm going to do a Release build or if I should install both version in Unity and it'll select the right one. Thanks!

    Read the article

  • Methods of learning / teaching programming

    - by Mark Avenius
    When I was in school, I had a difficult time getting into programming because of a catch-22 in the learning process: I didn't know how to write anything because I didn't know what keywords and commands meant. For example (as a student, I would think), "what does this using namespace std; thing do anyway? I didn't know what keywords and commands meant because I hadn't written anything. This basically led me to spending countless long night cursing the compiler as I made minor tweaks to my assignments until they would compile (and hopefully perform whatever operation they were supposed to). Is there a teaching/learning method that anyone uses that gets around this catch-22? I am trying to make this non-argumentative, which is why I don't want to know the 'best' method, but rather which methods exist.

    Read the article

  • How should I log time spent on multiple tasks?

    - by xenoterracide
    In Joel's blog on evidence based scheduling he suggests making estimates based on the smallest unit of work and logging extra work back to the original task. The problem I'm now experiencing is that I'll have create object A with subtask method A which creates object B and test all of the above. I create tasks for each of these that seems to be resulting in ok-ish estimates (need practice), but when I go to log work I find that I worked on 4 tasks at once because I tweak method A and find a bug in the test and refactor object B all while coding it. How should I go about logging this work? should I say I spent, for example, 2 hours on each of the 4 tasks I worked on in the 8 hour day?

    Read the article

  • SQL SERVER – Creating All New Database with Full Recovery Model

    - by pinaldave
    Sometimes, complex problems have very simple solutions. Let us see the following email which I received recently. “Hi Pinal, In our system when we create new database, by default, they are all created with the Simple Recovery Model. We have to manually change the recovery model after we create the database. We used the following simple T-SQL code: CREATE DATABASE dbname. We are very frustrated with this situation. We want all our databases to have the Full Recovery Model option by default. We are considering the following methods; please suggest the most efficient one among them. 1) Creating a Policy; when it is violated, the database model can be fixed 2) Triggers at Server Level 3) Automated Job which goes through all the databases and checks their recovery model; if the DBA has not changed the model, then the job will list the Databases and change their recovery model Also, we have a situation where we need a database in the Simple Recovery Model as well – how to white list them? Please suggest the best method.” Indeed, an interesting email! The answer to their question, i.e., which is the best method to fit their needs (white list, default, etc)? It will be NONE of the above. Here is the solution in one line and also the easiest way: Just go to your Model database: Path in SSMS >> Databases > System Databases >> model >> Right Click Properties >> Options >> Recovery Model - Select Full from dropdown. Every newly created database takes its base template from the Model Database. If you create a custom SP in the Model Database, when you create a new database, it will automatically exist in that database. Any database that was already created before making changes in the Model Database will not be affected at all. Creating Policy is also a good method, and I will blog about this in a separate blog post, but looking at current specifications of the reader, I think the Model Database should be modified to have a Full Recovery Option. While writing this blog post, I remembered my another blog post where the model database log file was growing drastically even though there were no transactions SQL SERVER – Log File Growing for Model Database – model Database Log File Grew Too Big. NOTE: Please do not touch the Model Database unnecessary. It is a strict “No.” If you want to create an object that you need in all the databases, then instead of creating it in model database, I suggest that you create a new database called maintenance and create the object there. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, Readers Question, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

    Read the article

  • Visual Studio Service Pack 1 - Test first!

    - by CraigG
    It appears that our run of fairly benign VS SP’s is over… I've now installed the VS 2010 SP1 in a few simple test environments (x64) and all of them are having issues. Add-in failures, failed package loading, missing SQL Intellisense, XAML designer failure, etc. Make sure you test this Service Pack thoroughly before you release it to your production environment. Microsoft Connect is the official repository for issues with Service Pack 1.

    Read the article

  • Slick and Timers?

    - by user3491043
    I'm making a game where I need events to happen in a precise amount of time. Explanation : I want that event A happens at 12000ms, and event B happens every 10000ms. So "if"s should looks like this. //event A if(Ticks == 12000) //do things //even B if(Ticks % 10000 == 0) //do stuff But now how can I have this "Ticks" value ? I tried to declare an int and then increasing it in the update method, I tried 2 ways of increasing it : Ticks++; It doesn't works because the update method is not always called every microseconds. Ticks += delta; It's kinda good but the delta is not always equals to 1, so I can miss the precise values I need in the if statements So if you know how can I do events in a precise amount of time please tell me how can I do this

    Read the article

  • New release of Microsoft All-In-One Code Framework is available for download - March 2011

    - by Jialiang
    A new release of Microsoft All-In-One Code Framework is available on March 8th. Download address: http://1code.codeplex.com/releases/view/62267#DownloadId=215627 You can download individual code samples or browse code samples grouped by technology in the updated code sample index. If it’s the first time that you hear about Microsoft All-In-One Code Framework, please read this Microsoft News Center article http://www.microsoft.com/presspass/features/2011/jan11/01-13codeframework.mspx, or watch the introduction video on YouTube http://www.youtube.com/watch?v=cO5Li3APU58, or read the introduction on our homepage http://1code.codeplex.com/. -------------- New Silverlight code samples CSSLTreeViewCRUDDragDrop Download: http://1code.codeplex.com/releases/view/62253#DownloadId=215808 The code sample was created by Amit Dey. It demonstrates a custom TreeView with added functionalities of CRUD (Create, Read, Update, Delete) and drag-and-drop operations. Silverlight TreeView control with CRUD and drag & drop is a frequently asked programming question in Silverlight  forums. Many customers also requested this code sample in our code sample request service. We hope that this sample can reduce developers' efforts in handling this typical programming scenario. The following blog article introduces the sample in detail: http://blogs.msdn.com/b/codefx/archive/2011/02/15/silverlight-treeview-control-with-crud-and-drag-amp-drop.aspx. CSSL4FileDragDrop and VBSL4FileDragDrop Download: http://1code.codeplex.com/releases/view/62253#DownloadId=215809 http://1code.codeplex.com/releases/view/62253#DownloadId=215810 The code sample demonstrates the new drag&drop feature of Silverlight 4 to implement dragging picures from the local file system to a Silverlight application.   Sometimes we want to change SiteMapPath control's titles and paths according to Query String values. And sometimes we want to create the SiteMapPath dynamically. This code sample shows how to achieve these goals by handling SiteMap.SiteMapResolve event. CSASPNETEncryptAndDecryptConfiguration, VBASPNETEncryptAndDecryptConfiguration Download: http://1code.codeplex.com/releases/view/62253#DownloadId=215027 http://1code.codeplex.com/releases/view/62253#DownloadId=215106 In this sample, we encrypt and decrypt some sensitive information in the config file of a web application by using the RSA asymmetric encryption. This project contains two snippets. The first one demonstrates how to use RSACryptoServiceProvider to generate public key and the corresponding private key and then encrypt/decrypt string value on page. The second part shows how to use RSA configuration provider to encrypt and decrypt configuration section in web.config of web application. connectionStrings section in plain text: Encrypted connectionString:  Note that if you store sensitive data in any of the following configuration sections, we cannot encrypt it by using a protected configuration provider <processModel> <runtime> <mscorlib> <startup> <system.runtime.remoting> <configProtectedData> <satelliteassemblies> <cryptographySettings> <cryptoNameMapping> CSASPNETFileUploadStatus Download: http://1code.codeplex.com/releases/view/62253#DownloadId=215028 I believe ASP.NET programmers will like this sample, because in many cases we need customers know the current status of the uploading files, including the upload speed and completion percentage and so on. Under normal circumstances, we need to use COM components to accomplish this function, such as Flash, Silverlight, etc. The uploading data can be retrieved in two places, the client-side and the server-side. For the client, for the safety factors, the file upload status information cannot be got from JavaScript or server-side code, so we need COM component, like Flash and Silverlight to accomplish this, I do not like this approach because the customer need to install these components, but also we need to learn another programming framework. For the server side, we can get the information through coding, but the key question is how to tell the client results. In this case, We will combine custom HTTPModule and AJAX technology to illustrate how to analyze the HTTP protocol, how to break the file request packets, how to customize the location of the server-side file caching, how to return the file uploading status back to the client and so on . CSASPNETHighlightCodeInPage, VBASPNETHighlightCodeInPage Download: http://1code.codeplex.com/releases/view/62253#DownloadId=215029 http://1code.codeplex.com/releases/view/62253#DownloadId=215108 This sample imitates a system that needs display the highlighted code in an ASP.NET page . As a matter of fact, sometimes we input code like C# or HTML in a web page and we need these codes to be highlighted for a better reading experience. It is convenient for us to keep the code in mind if it is highlighted. So in this case, the sample shows how to highlight the code in an ASP.NET page. It is not difficult to highlight the code in a web page by using String.Replace method directly. This  method can return a new string in which all occurrences of a specified string in the current instance are replaced with another specified string. However, it may not be a good idea, because it's not extremely fast, in fact, it's pretty slow. In addition, it is hard to highlight multiple keywords by using String.Replace method directly. Sometimes we need to copy source code from visual studio to a web page, for readability purpose, highlight the code is important while set the different types of keywords to different colors in a web page by using String.Replace method directly is not available. To handle this issue, we need to use a hashtable variable to store the different languages of code and their related regular expressions with matching options. Furthermore, define the css styles which used to highlight the code in a web page. The sample project can auto add the style object to the matching string of code. A step-by-step guide illustrating how to highlight the code in an ASP.NET page: 1. the HighlightCodePage.aspx page Choose a type of language in the dropdownlist control and paste the code in the textbox control, then click the HighLight button. 2.  Display the highlighted code in an ASP.NET page After user clicks the HighLight button, the highlighted code will be displayed at right side of the page.        CSASPNETPreventMultipleWindows Download: http://1code.codeplex.com/releases/view/62253#DownloadId=215032 This sample demonstrates a step-by-step guide illustrating how to detect and prevent multiple windows or tab usage in Web Applications. The sample imitates a system that need to prevent multiple windows or tabs to solve some problems like sharing sessions, protect duplicated login, data concurrency, etc. In fact, there are many methods achieving this goal. Here we give a solution of use JavaScript, Sample shows how to use window.name property check the correct links and throw other requests to invalid pages. This code-sample use two user controls to make a distinction between base page and target page, user only need drag different controls to appropriate web form pages. so user need not write repetitive code in every page, it will make coding work lightly and convenient for modify your code.  JSVirtualKeyboard Download: http://1code.codeplex.com/releases/view/62253#DownloadId=215093 This article describes an All-In-One framework sample that demonstrates a step-by-step guide illustrating how to build a virtual keyboard in your HTML page. Sometimes we may need to offer a virtual keyboard to let users input something without their real keyboards. This scenario often occurs when users will enter their password to get access to our sites and we want to protect the password from some kinds of back-door software, a Key-logger for example, and we will find a virtual keyboard on the page will be a good choice here. To create a virtual keyboard, we firstly need to add some buttons to the page. And when users click on a certain button, the JavaScript function handling the onclick event will input an appropriated character to the textbox. That is the simple logic of this feature. However, if we indeed want a virtual keyboard to substitute for the real keyboard completely, we will need more advanced logic to handle keys like Caps-Lock and Shift etc. That will be a complex work to achieve. CSASPNETDataListImageGallery Download: http://1code.codeplex.com/releases/view/62261#DownloadId=215267 This code sample demonstrates how to create an Image Gallery application by using the DataList control in ASP.NET. You may find the Image Gallery is widely used in many social networking sites, personal websites and E-Business websites. For example, you may use the Image Gallery to show a library of personal uploaded images on a personal website. Slideshow is also a popular tool to display images on websites. This code sample demonstrates how to use the DataList and ImageButton controls in ASP.NET to create an Image Gallery with image navigation. You can click on a thumbnail image in the Datalist control to display a larger version of the image on the page. This sample code reads the image paths from a certain directory into a FileInfo array. Then, the FileInfo array is used to populate a custom DataTable object which is bound to the Datalist control. This code sample also implements a custom paging system that allows five images to be displayed horizontally on one page. The following link buttons are used to implement a custom paging system:   •     First •     Previous •     Next •     Last Note We recommend that you use this method to load no more than five images at a time. You can also set the SelectedIndex property for the DataList control to limit the number of the thumbnail images that can be selected. To indicate which image is selected, you can set the SelectedStyle property for the DataList control. VBASPNETSearchEngine Download: http://1code.codeplex.com/releases/view/62253#DownloadId=215112 This sample shows how to implement a simple search engine in an ASP.NET web site. It uses LIKE condition in SQL statement to search database. Then it highlights keywords in search result by using Regular Expression and JavaScript. New Windows General code samples CSCheckEXEType, VBCheckEXEType Downloads: http://1code.codeplex.com/releases/view/62253#DownloadId=215045 http://1code.codeplex.com/releases/view/62253#DownloadId=215120 The sample demonstrates how to check an executable file type.  For a given executable file, we can get 1 whether it is a console application 2 whether it is a .Net application 3 whether it is a 32bit native application. 4 The full display name of a .NET application, e.g. System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089, processorArchitecture=MSIL New Internet Explorer code samples CSIEExplorerBar, VBIEExplorerBar Downloads: http://1code.codeplex.com/releases/view/62253#DownloadId=215060 http://1code.codeplex.com/releases/view/62253#DownloadId=215133 The sample demonstrates how to create and deploy an IE Explorer Bar which could list all the images in a web page. CSBrowserHelperObject, VBBrowserHelperObject Downloads: http://1code.codeplex.com/releases/view/62253#DownloadId=215044 http://1code.codeplex.com/releases/view/62253#DownloadId=215119 The sample demonstrates how to create and deploy a Browser Helper Object,  and the BHO in this sample is used to disable the context menu in IE. New Windows Workflow Foundation code samples CSWF4ActivitiesCorrelation Download: http://1code.codeplex.com/releases/view/62253#DownloadId=215085 Consider that there are two such workflow instances:       start                                   start          |                                           | Receive activity      Receive activity         |                                           | Receive2 activity      Receive2 activity         |                                           | A WCF request comes to call the second Receive2 activity. Which one should take care of the request? The answer is Correlation. This sample will show you how to correlate two workflow service to work together. -------------- New ASP.NET code samples CSASPNETBreadcrumbWithQueryString Download: http://1code.codeplex.com/releases/view/62253#DownloadId=215022

    Read the article

  • Optimizing graphics for an iOS flash game

    - by 1GR3
    A friend of mine and myself are working on a flash developed iOS (and later Android) puzzle board game. He's a developer and I'm a designer/developer so (no surprise) we have different points of view. His method: make small tiles (100x100px) in Photoshop join them into the board and then in flash apply effects to the board to avoid repetition (80's not in the good way). My method: precompose the whole board (960x640px+bleed) in Photoshop and than mask active and inactive areas in flash. What do you think?

    Read the article

  • How (recipe) to build only one kernel module?

    - by Pro Backup
    I have a bug in a Linux kernel module that causes the stock Ubuntu 14.04 kernel to oops (crash). That is why I want to edit/patch the source of only that single kernel module to add some extra debug output. The kernel module in question is mvsas and not necessary to boot. For that reason I don't see any need to update any initrd images. I have read a lot of information (as shown below) and find the setup and build process confusion. I need two recipes: to setup/configure the build environment once steps to do after editing any source file of this kernel module (.c and .h) and converting that edit into a new kernel module (.ko) The sources that have been used are: build one kernel module - Google search http://www.linuxquestions.org/questions/linux-kernel-70/rebuilding-a-single-kernel-module-595116/ http://stackoverflow.com/questions/8744087/how-to-recompile-just-a-single-kernel-module http://www.pixelbeat.org/docs/rebuild_kernel_module.html How do I build a single in-tree kernel module? http://ubuntuforums.org/showthread.php?t=1153067 http://ubuntuforums.org/showthread.php?t=2112166 http://ubuntuforums.org/showthread.php?t=1115593 build one kernel module ubuntu - Google search 'make +single +kernel +module' - Ask Ubuntu 'make +kernel +module' - Ask Ubuntu My makefile results in: No rule to make target `arch/x86/tools/relocs.c', needed '"Invalid module format"' - Ask Ubuntu Driver installation: compiling source code for newer kernel Modprobe: 'Invalid nodule format', yet works after insmod "Symbol version dump" "is missing" - Google search http://stackoverflow.com/questions/9425523/should-i-care-that-the-symbol-version-dump-is-missing-how-do-i-get-one Where can I find the corresponding Module.symvers and .config files for 12.04.3 i386 server? "no symbol version for module_layout" when trying to load usbhid.ko Broken links inside Linux header file folder 'make modules_install' - Ask Ubuntu 'modules_install' - Ask Ubuntu Empty build directory in custom compiled kernel Not able to see pr_info output In which directory are the kernel source files and how can I recompile it? How can I compile and install that patched libata-eh.c file? 'modules_install +depmod' - Ask Ubuntu modules_install depmod - Google search "make modules_install" - Google search http://www.csee.umbc.edu/courses/undergraduate/CMSC421/fall02/burt/projects/howto_build_kernel.html http://unix.stackexchange.com/questions/20864/what-happens-in-each-step-of-the-linux-kernel-building-process https://wiki.ubuntu.com/KernelCustomBuild http://www.cyberciti.biz/tips/build-linux-kernel-module-against-installed-kernel-source-tree.html http://www.linuxforums.org/forum/kernel/170617-solved-make-modules_install-different-path.html "make prepare" - Google search "make prepare" "scripts/kconfig/conf --silentoldconfig Kconfig" - Google search http://ubuntuforums.org/showthread.php?t=1963515 ubuntu "make prepare" version - Google search http://stackoverflow.com/questions/8276245/how-to-compile-a-kernel-module-against-a-new-source https://help.ubuntu.com/community/Kernel/Compile How do I compile a kernel module? How to add a custom driver to my kernel? Compile and loading kernel module without compiling the kernel

    Read the article

  • AWS .NET SDK v2: the message-pump pattern

    - by Elton Stoneman
    Originally posted on: http://geekswithblogs.net/EltonStoneman/archive/2013/10/11/aws-.net-sdk-v2--the-message-pump-pattern.aspxVersion 2 of the AWS SDK for .NET has had a few pre-release iterations on NuGet and is stable, if a bit lacking in step-by-step guides. There’s at least one big reason to try it out: the SQS queue client now supports asynchronous reads, so you don’t need a clumsy polling mechanism to retrieve messages. The new approach  is easy to use, and lets you work with AWS queues in a similar way to the message-pump pattern used in the latest Azure SDK for Service Bus queues and topics. I’ve posted a simple wrapper class for subscribing to an SQS hub on gist here: A wrapper for the SQS client in the AWS SDK for.NET v2, which uses the message-pump pattern. Here’s the core functionality in the subscribe method: private async void Subscribe() { if (_isListening) { var request = new ReceiveMessageRequest { MaxNumberOfMessages = 10 }; request.QueueUrl = QueueUrl; var result = await _sqsClient.ReceiveMessageAsync(request, _cancellationTokenSource.Token); if (result.Messages.Count > 0) { foreach (var message in result.Messages) { if (_receiveAction != null && message != null) { _receiveAction(message.Body); DeleteMessage(message.ReceiptHandle); } } } } if (_isListening) { Subscribe(); } } which you call with something like this: client.Subscribe(x=>Log.Debug(x.Body)); The async SDK call returns when there is something in the queue, and will run your receive action for every message it gets in the batch (defaults to the maximum size of 10 messages per call). The listener will sit there awaiting messages until you stop it with: client.Unsubscribe(); Internally it has a cancellation token which it sets when you call unsubscribe, which cancels any in-flight call to SQS and stops the pump. The wrapper will also create the queue if it doesn’t exist at runtime. The Ensure() method gets called in the constructor so when you first use the client for a queue (sending or subscribing), it will set itself up: if (!Exists()) { var request = new CreateQueueRequest(); request.QueueName = QueueName; var response = _sqsClient.CreateQueue(request); QueueUrl = response.QueueUrl; } The Exists() check has to do make a call to ListQueues on the SNS client, as it doesn’t provide its own method to check if a queue exists. That call also populates the Amazon Resource Name, the unique identifier for this queue, which will be useful later. To use the wrapper, just instantiate and go: var queueClient = new QueueClient(“ProcessWorkflow”); queueClient.Subscribe(x=>Log.Debug(x.Body)); var message = {}; //etc. queueClient.Send(message);

    Read the article

  • Do private static methods in C# hurt anything?

    - by fish
    I created a private validation method for a certain validation that happens multiple times in my class (I can't store the validated data for various reasons). Now, ReSharper suggests that the function could be made static. I'm a little reluctant to do so due known problems with static methods. It would be a private static method. My question is, can private static methods cause similar coupling and testing problems like public static methods? Is it a bad practice? I would guess not, but I'm not sure if there is a pitfall here.

    Read the article

  • SQL SERVER – Puzzle Involving NULL – Resolve – Error – Operand data type void type is invalid for sum operator

    - by pinaldave
    Today is Monday let us start this week with interesting puzzle. Yesterday I had also posted quick question here: SQL SERVER – T-SQL Scripts to Find Maximum between Two Numbers Run following code: SELECT SUM(data) FROM (SELECT NULL AS DATA) t It will throw following error. Msg 8117, Level 16, State 1, Line 1 Operand data type void type is invalid for sum operator. I can easily fix if I use ISNULL Function as displayed following. SELECT SUM(data) FROM (SELECT ISNULL(NULL,0) AS DATA) t Above script will not throw an error. However, there is one more method how this can be fixed. Can you come up with another method which will not generate error? Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Puzzle, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology

    Read the article

  • How to install postgresql-8.4?

    - by ted
    sudo add-apt-repository ppa:pitti/postgresql # ... OK sudo apt-get install postgresql-8.4 Reading package lists... Done Building dependency tree Reading state information... Done Package postgresql-8.4 is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source E: Package 'postgresql-8.4' has no installation candidate Should I download it from http://packages.debian.org/squeeze/postgresql-8.4 and manually install all the dependencies?

    Read the article

  • Dynamic Tab Implementation in ADF

    - by Vijay Mohan
    Well, this can be a common usecase across apps to open tabs dynamically at runtime based on the request.Well, in order to achieve this you can have a parent container, lets say a panelTab component.Inside panelTab , u can have a showDetailItem inside an af:foreach or an af:iterator binded to a bean static list which will have as many show detail items as you wish to be shown.something like this.private static List = { new showDetailItem("1"),new ShowDetailItem("2") ...};now in the backing bean you can have a method that takes care of rendering and disclosing an specific tab based on the index.public void openMyTab(){List<MyItems> list = refToParentContainer.getChildren();int indexOfTabToBeOpened = //Write a method that will compute the tab index of the next //tab.list.get(index).setRendered(true);list.get(index).setDisclosed(true);similarly you can set other properties too.}Else, instead of having af:foreach/iterator iterating through the SD items , you can go for static SDs in the page with render property set to false and then you can follow the same approach to render/disclose it at runtime.

    Read the article

  • SQL Server MCM is too easy, is it?

    - by simonsabin
    We all know that Brent Ozar did the MCM training/certification over the past few weeks. He wrote an interesting article on Friday about the bad bits ( http://www.brentozar.com/archive/2010/04/sql-mcm-now-bad-stuff/ ) of the training and it lead me to thinking about the certification process again(I often think about it, and it appears often in response to something from Brent http://sqlblogcasts.com/blogs/simons/archive/2010/02/12/Whats-missing-in-the-SQL-Certification-process-.aspx ) This time what...(read more)

    Read the article

  • Building Publishing Pages in Code

    - by David Jacobus
    Originally posted on: http://geekswithblogs.net/djacobus/archive/2013/10/27/154478.aspxOne of the Mantras we developers try to follow: Ensure that the solution package we deliver to the client is complete.  We build Web Parts, Master Pages, Images, CSS files and other artifacts that we push to the client with a WSP (Solution Package) And then we have them finish the solution by building their site pages by adding the web parts to the site pages.       I am a proponent that we,  the developers,  should minimize this time consuming work and build these site pages in code.  I found a few blogs and some MSDN documentation but not really a complete solution that has all these artifacts working in one solution.   What I am will discuss and provide a solution for is a package that has: 1.  Master Page 2.  Page Layout 3.  Page Web Parts 4.  Site Pages   Most all done in code without the development team or the developers having to finish up the site building process spending a few hours or days completing the site!  I am not implying that in Development we do this. In fact,  we build these pages incrementally testing our web parts, etc. I am saying that the final action in our solution is that we take all these artifacts and add them to the site pages in code, the client then only needs to activate a few features and VIOLA their site appears!.  I had a project that had me build 8 pages like this as part of the solution.   In this blog post, I am taking a master page solution that I have called DJGreenMaster.  On My Office 365 Development Site it looks like this:     It is a generic master page for a SharePoint 2010 site Along with a three column layout.  Centered with a footer that uses a SharePoint List and Web Part for the footer links.  I use this master page a lot in my site development!  Easy to change the color and site logo with a little CSS.   I am going to add a few web parts for discussion purposes and then add these web parts to a site page in code.    Lets look at the solution package for DJ Green Master as that will be the basis project for building the site pages:   What you are seeing  is a complete solution to add a Master Page to a site collection which contains: 1.  Master Page Module which contains the Master Page and Page Layout 2.  The Footer Module to add the Footer Web Part 3.  Miscellaneous modules to add images, JQuery, CSS and subsite page 4.  3 features and two feature event receivers: a.  DJGreenCSS, used to add the master page CSS file to Style Sheet Library and an Event Receiver to check it in. b.  DJGreenMaster used to add the Master Page and Page Layout.  In an Event Receiver change the master page to DJGreenMaster , create the footer list and check the files in. c.  DJGreenMasterWebParts add the Footer Web Part to the site collection. I won’t go over the code for this as I will give it to you at the end of this blog post. I have discussed creating a list in code in a previous post.  So what we have is the basis to begin what is germane to this discussion.  I have the first two requirements completed.  I need now to add page web parts and the build the pages in code.  For the page web parts, I will use one downloaded from Codeplex which does not use a SharePoint custom list for simplicity:   Weather Web Part and another downloaded from MSDN which is a SharePoint Custom Calendar Web Part, I had to add some functionality to make the events color coded to exceed the built-in 10 overlays using JQuery!    Here is the solution with the added projects:     Here is a screen shot of the Weather Web Part Deployed:   Here is a screen shot of the Site Calendar with JQuery:     Okay, Now we get to the final item:  To create Publishing pages.   We need to add a feature receiver to the DJGreenMaster project I will name it DJSitePages and also add a Event Receiver:       We will build the page at the site collection level and all of the code necessary will be contained in the event receiver.   Added a reference to the Microsoft.SharePoint.Publishing.dll contained in the ISAPI folder of the 14 Hive.   First we will add some static methods from which we will call  in our Event Receiver:   1: private static void checkOut(string pagename, PublishingPage p) 2: { 3: if (p.Name.Equals(pagename, StringComparison.InvariantCultureIgnoreCase)) 4: { 5: 6: if (p.ListItem.File.CheckOutType == SPFile.SPCheckOutType.None) 7: { 8: p.CheckOut(); 9: } 10:   11: if (p.ListItem.File.CheckOutType == SPFile.SPCheckOutType.Online) 12: { 13: p.CheckIn("initial"); 14: p.CheckOut(); 15: } 16: } 17: } 18: private static void checkin(PublishingPage p,PublishingWeb pw) 19: { 20: SPFile publishFile = p.ListItem.File; 21:   22: if (publishFile.CheckOutType != SPFile.SPCheckOutType.None) 23: { 24:   25: publishFile.CheckIn( 26:   27: "CheckedIn"); 28:   29: publishFile.Publish( 30:   31: "published"); 32: } 33: // In case of content approval, approve the file need to add 34: //pulishing site 35: if (pw.PagesList.EnableModeration) 36: { 37: publishFile.Approve("Initial"); 38: } 39: publishFile.Update(); 40: }   In a Publishing Site, CheckIn and CheckOut  are required when dealing with pages in a publishing site.  Okay lets look at the Feature Activated Event Receiver: 1: public override void FeatureActivated(SPFeatureReceiverProperties properties) 2: { 3:   4:   5:   6: object oParent = properties.Feature.Parent; 7:   8:   9:   10: if (properties.Feature.Parent is SPWeb) 11: { 12:   13: currentWeb = (SPWeb)oParent; 14:   15: currentSite = currentWeb.Site; 16:   17: } 18:   19: else 20: { 21:   22: currentSite = (SPSite)oParent; 23:   24: currentWeb = currentSite.RootWeb; 25:   26: } 27: 28:   29: //create the publishing pages 30: CreatePublishingPage(currentWeb, "Home.aspx", "ThreeColumnLayout.aspx","Home"); 31: //CreatePublishingPage(currentWeb, "Dummy.aspx", "ThreeColumnLayout.aspx","Dummy"); 32: }     Basically we are calling the method Create Publishing Page with parameters:  Current Web, Name of the Page, The Page Layout, Title of the page.  Let’s look at the Create Publishing Page method:   1:   2: private void CreatePublishingPage(SPWeb site, string pageName, string pageLayoutName, string title) 3: { 4: PublishingSite pubSiteCollection = new PublishingSite(site.Site); 5: PublishingWeb pubSite = null; 6: if (pubSiteCollection != null) 7: { 8: // Assign an object to the pubSite variable 9: if (PublishingWeb.IsPublishingWeb(site)) 10: { 11: pubSite = PublishingWeb.GetPublishingWeb(site); 12: } 13: } 14: // Search for the page layout for creating the new page 15: PageLayout currentPageLayout = FindPageLayout(pubSiteCollection, pageLayoutName); 16: // Check or the Page Layout could be found in the collection 17: // if not (== null, return because the page has to be based on 18: // an excisting Page Layout 19: if (currentPageLayout == null) 20: { 21: return; 22: } 23:   24: 25: PublishingPageCollection pages = pubSite.GetPublishingPages(); 26: foreach (PublishingPage p in pages) 27: { 28: //The page allready exists 29: if ((p.Name == pageName)) return; 30:   31: } 32: 33:   34:   35: PublishingPage newPage = pages.Add(pageName, currentPageLayout); 36: newPage.Description = pageName.Replace(".aspx", ""); 37: // Here you can set some properties like: 38: newPage.IncludeInCurrentNavigation = true; 39: newPage.IncludeInGlobalNavigation = true; 40: newPage.Title = title; 41: 42: 43:   44:   45: 46:   47: //build the page 48:   49: 50: switch (pageName) 51: { 52: case "Homer.aspx": 53: checkOut("Courier.aspx", newPage); 54: BuildHomePage(site, newPage); 55: break; 56:   57:   58: default: 59: break; 60: } 61: // newPage.Update(); 62: //Now we can checkin the newly created page to the “pages” library 63: checkin(newPage, pubSite); 64: 65: 66: }     The narrative in what is going on here is: 1.  We need to find out if we are dealing with a Publishing Web.  2.  Get the Page Layout 3.  Create the Page in the pages list. 4.  Based on the page name we build that page.  (Here is where we can add all the methods to build multiple pages.) In the switch we call Build Home Page where all the work is done to add the web parts.  Prior to adding the web parts we need to add references to the two web part projects in the solution. using WeatherWebPart.WeatherWebPart; using CSSharePointCustomCalendar.CustomCalendarWebPart;   We can then reference them in the Build Home Page method.   Let’s look at Build Home Page: 1:   2: private static void BuildHomePage(SPWeb web, PublishingPage pubPage) 3: { 4: // build the pages 5: // Get the web part manager for each page and do the same code as below (copy and paste, change to the web parts for the page) 6: // Part Description 7: SPLimitedWebPartManager mgr = web.GetLimitedWebPartManager(web.Url + "/Pages/Home.aspx", System.Web.UI.WebControls.WebParts.PersonalizationScope.Shared); 8: WeatherWebPart.WeatherWebPart.WeatherWebPart wwp = new WeatherWebPart.WeatherWebPart.WeatherWebPart() { ChromeType = PartChromeType.None, Title = "Todays Weather", AreaCode = "2504627" }; 9: //Dictionary<string, string> wwpDic= new Dictionary<string, string>(); 10: //wwpDic.Add("AreaCode", "2504627"); 11: //setWebPartProperties(wwp, "WeatherWebPart", wwpDic); 12:   13: // Add the web part to a pagelayout Web Part Zone 14: mgr.AddWebPart(wwp, "g_685594D193AA4BBFABEF2FB0C8A6C1DD", 1); 15:   16: CSSharePointCustomCalendar.CustomCalendarWebPart.CustomCalendarWebPart cwp = new CustomCalendarWebPart() { ChromeType = PartChromeType.None, Title = "Corporate Calendar", listName="CorporateCalendar" }; 17:   18: mgr.AddWebPart(cwp, "g_20CBAA1DF45949CDA5D351350462E4C6", 1); 19:   20:   21: pubPage.Update(); 22:   23: } Here is what we are doing: 1.  We got  a reference to the SharePoint Limited Web Part Manager and linked/referenced Home.aspx  2.  Instantiated the a new Weather Web Part and used the Manager to add it to the page in a web part zone identified by ID,  thus the need for a Page Layout where the developer knows the ID’s. 3.  Instantiated the Calendar Web Part and used the Manager to add it to the page. 4. We the called the Publishing Page update method. 5.  Lastly, the Create Publishing Page method checks in the page just created.   Here is a screen shot of the page right after a deploy!       Okay!  I know we could make a home page look much better!  However, I built this whole Integrated solution in less than a day with the caveat that the Green Master was already built!  So what am I saying?  Build you web parts, master pages, etc.  At the very end of the engagement build the pages.  The client will be very happy!  Here is the code for this solution Code

    Read the article

  • Interpolating Matrices

    - by sebf
    Hello, Apologies if I am missing something very obvious (likely!) but is there anything wrong with interpolating between two matrices by: float d = (float)(targetTime.Ticks - keyframe_start.ticks) / (float)(keyframe_end.ticks - keyframe_start.ticks); return ((keyframe_start.Transform * (1 - d)) + (keyframe_end.Transform * d)); As in my app, when I try an use this to interpolate between two keyframes, the model begins to 'shrink' - the severity based on how far between the two keyframes the target time is; its worst when the transform split is ~50/50.

    Read the article

  • Introducing jLight &ndash; Talking to the DOM using Silverlight and jQuery.

    - by Timmy Kokke
    Introduction With the recent news about Silverlight on the Windows Phone and all the great Out-Of-Browser features in the upcoming Silverlight 4 you almost forget Silverlight is a browser plugin. It most often runs in a web browser and often as a control. In many cases you need to communicate with the browser to get information about textboxes, events or details about the browser itself. To do this you can use JavaScript from Silverlight. Although Silverlight works the same on every browser, JavaScript does not and it won’t be long before problems arise. To overcome differences in browser I like to use jQuery. The only downside of doing this is that there’s a lot more code needed that you would normally use when you write jQuery in JavaScript. Lately, I had to catch changes is the browser scrollbar and act to the new position. I also had to move the scrollbar when the user dragged around in the Silverlight application. With jQuery it was peanuts to get and set the right attributes, but I found that I had to write a lot of code on Silverlight side.  With a few refactoring I had a separated out the plumbing into a new class and could call only a few methods on that to get the same thing done. The idea for jLight was born. jLight vs. jQuery The main purpose of jLight is to take the ease of use of jQuery and bring it into Silverlight for handling DOM interaction. For example, to change the text color of a DIV to red, in jQuery you would write: jQuery("div").css("color","red"); In jLight the same thing looks like so: jQuery.Select("div").Css("color","red");   Another example. To change the offset in of the last SPAN you could write this in jQuery : jQuery("span:last").offset({left : 10, top : 100});   In jLight this would do the same: jQuery.Select("span:last").Offset(new {left = 10, top = 100 });   Callbacks Nothing too special so far. To get the same thing done using the “normal” HtmlPage.Window.Eval, it wouldn’t require too much effort. But to wire up a handler for events from the browser it’s a whole different story. Normally you need to register ScriptMembers, ScriptableTypes or write some code in JavaScript. jLight takes care of the plumbing and provide you with an simple interface in the same way jQuery would. If you would like to handle the scroll event of the BODY of your html page, you’ll have to bind the event using jQuery and have a function call back to a registered function in Silverlight. In the example below I assume there’s a method “SomeMethod” and it is registered as a ScriptableObject as “RegisteredFromSilverlight” from Silverlight.   jQuery("body:first").scroll(function() { var sl = document.getElementbyId("SilverlightControl"); sl.content.RegisteredFromSilverlight.SomeMethod($(this)); });       Using jLight  in Silverlight the code would be even simpler. The registration of RegisteredFromSilverlight  as ScriptableObject can be omitted.  Besides that, you don’t have to write any JavaScript or evaluate strings with JavaScript.   jQuery.Select("body:first").scroll(SomeMethod);   Lambdas Using a lambda in Silverlight can make it even simpler.  Each is the jQuery equivalent of foreach in C#. It calls a function for every element found by jQuery. In this example all INPUT elements of the text type are selected. The FromObject method is used to create a jQueryObject from an object containing a ScriptObject. The Val method from jQuery is used to get the value of the INPUT elements.   jQuery.Select("input:text").Each((element, index) => { textBox1.Text += jQueryObject.FromObject(element).Val(); return null; });   Ajax One thing jQuery is often used for is making Ajax calls. Making calls to services to external services can be done from Silverlight, but as easy as using jQuery. As an example I would like to show how jLight does this. Below is the entire code behind. It searches my name on twitter and shows the result. This example can be found in the source of the project. The GetJson method passes a Silverlight JsonValue to a callback. This callback instantiates Twit objects and adds them to a ListBox called TwitList.   public partial class DemoPage2 : UserControl { public DemoPage2() { InitializeComponent(); jQuery.Load(); }   private void CallButton_Click(object sender, RoutedEventArgs e) { jQuery.GetJson("http://search.twitter.com/search.json?lang=en&q=sorskoot", Done); }   private void Done(JsonValue arg) { var tweets = new List<Twit>(); foreach (JsonObject result in arg["results"]) { tweets.Add(new Twit() { Text = (string)result["text"], Image = (string)result["profile_image_url"], User = (string)result["from_user"] } ); } TwitList.ItemsSource = tweets; } }   public class Twit { public string User { get; set; } public string Image { get; set; } public string Text { get; set; } }   Conclusion Although jLight is still in development it can be used already.There isn’t much documentation yet, but if you know jQuery jLight isn’t very hard to use.  If you would like to try it, please let me know what you think and report any problems you run in to. jLight can be found at:   http://jlight.codeplex.com

    Read the article

  • InvokeRequired not reliable?

    - by marocanu2001
    InvalidOperationException: Cross-thread operation not valid: Control 'progressBar' accessed from a thread other than the thread it was created ... Now this is not a nice way to start a day! not even if it's a Monday! So you have seen this and already thought, come on, this is an old one, just ask whether InvokeRequired before calling the method in the control, something like this: if (progressBar.InvokeRequired) {           progressBar.Invoke  ( new MethodInvoker( delegate {  progressBar.Value = 50;    }) ) }else      progressBar.Value = 50;    Unfortunately this was not working the way I would have expected, I got this error, debugged and though in debugging the InvokeRequired had become true , the error was thrown on the branch that did not required Invoke. So there was a scenario where InvokeRequired returned false and still accessing the control was not on the right thread ... Problem was that I kept showing and hiding the little form showing the progressbar. The progressbar was updating on an event  , ProgressChanged and I could not guarantee the little form was loaded by the time the event was thrown. So , spotted the problem, if none of the parents of the control you try to modify is created at the time of the method invoking, the InvokeRequired returns true! That causes your code to execute on the woring thread. Of course, updating UI before the win dow was created is not a legitimate action either, still I would have expected a different error. MSDN: "If the control's handle does not yet exist, InvokeRequired searches up the control's parent chain until it finds a control or form that does have a window handle. If no appropriate handle can be found, the InvokeRequired method returns false. This means that InvokeRequired can return false if Invoke is not required (the call occurs on the same thread), or if the control was created on a different thread but the control's handle has not yet been created." Have  a look at InvokeRequired's implementation: public bool InvokeRequired {     get     {         HandleRef hWnd;         int lpdwProcessId;         if (this.IsHandleCreated)         {             hWnd = new HandleRef(this, this.Handle);         }         else         {             Control wrapper = this.FindMarshallingControl();             if (!wrapper.IsHandleCreated)             {                 return false; // <==========             }             hWnd = new HandleRef(wrapper, wrapper.Handle);         }         int windowThreadProcessId = SafeNativeMethods.GetWindowThreadProcessId(hWnd, out lpdwProcessId);         int currentThreadId = SafeNativeMethods.GetCurrentThreadId();         return (windowThreadProcessId != currentThreadId);     } } Here 's a good article about this and a workaround http://www.ikriv.com/en/prog/info/dotnet/MysteriousHang.html

    Read the article

  • Why can't I configure my touchpad?

    - by Jorge Castro
    I want to disable my touchpad's "tap to click" feature. Searching for this on the internet comes up with suggestions to shut it off in the "Mouse" preferences, however I am missing the touchpad tab that people keep talking about: The closest official documentation I've been able to find is here. The touchpad also doesn't show up in gpointing-device-settings. Unchecking tap_to_click in the /desktop/gnome/peripherals/touchpad/ gconf key doesn't seem to do anything.

    Read the article

  • Where is /dev/dsp or /dev/audio?

    - by YumYumYum
    I have to apply sudo chmod a+r /dev/dsp or /dev/audio but in my Ubuntu 12.10 i do not have such. Where is then the PCM sound file for ssh? chmod: cannot access `/dev/dsp': No such file or directory chmod: cannot access `/dev/audio': No such file or directory Follow up: http://superuser.com/questions/244173/missing-dev-dsp-under-ubuntu I want to stream the sound output and input. So that i can capture any audio in/out to a file for recording.

    Read the article

  • C#/.NET Little Wonders: The Nullable static class

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. Today we’re going to look at an interesting Little Wonder that can be used to mitigate what could be considered a Little Pitfall.  The Little Wonder we’ll be examining is the System.Nullable static class.  No, not the System.Nullable<T> class, but a static helper class that has one useful method in particular that we will examine… but first, let’s look at the Little Pitfall that makes this wonder so useful. Little Pitfall: Comparing nullable value types using <, >, <=, >= Examine this piece of code, without examining it too deeply, what’s your gut reaction as to the result? 1: int? x = null; 2:  3: if (x < 100) 4: { 5: Console.WriteLine("True, {0} is less than 100.", 6: x.HasValue ? x.ToString() : "null"); 7: } 8: else 9: { 10: Console.WriteLine("False, {0} is NOT less than 100.", 11: x.HasValue ? x.ToString() : "null"); 12: } Your gut would be to say true right?  It would seem to make sense that a null integer is less than the integer constant 100.  But the result is actually false!  The null value is not less than 100 according to the less-than operator. It looks even more outrageous when you consider this also evaluates to false: 1: int? x = null; 2:  3: if (x < int.MaxValue) 4: { 5: // ... 6: } So, are we saying that null is less than every valid int value?  If that were true, null should be less than int.MinValue, right?  Well… no: 1: int? x = null; 2:  3: // um... hold on here, x is NOT less than min value? 4: if (x < int.MinValue) 5: { 6: // ... 7: } So what’s going on here?  If we use greater than instead of less than, we see the same little dilemma: 1: int? x = null; 2:  3: // once again, null is not greater than anything either... 4: if (x > int.MinValue) 5: { 6: // ... 7: } It turns out that four of the comparison operators (<, <=, >, >=) are designed to return false anytime at least one of the arguments is null when comparing System.Nullable wrapped types that expose the comparison operators (short, int, float, double, DateTime, TimeSpan, etc.).  What’s even odder is that even though the two equality operators (== and !=) work correctly, >= and <= have the same issue as < and > and return false if both System.Nullable wrapped operator comparable types are null! 1: DateTime? x = null; 2: DateTime? y = null; 3:  4: if (x <= y) 5: { 6: Console.WriteLine("You'd think this is true, since both are null, but it's not."); 7: } 8: else 9: { 10: Console.WriteLine("It's false because <=, <, >, >= don't work on null."); 11: } To make matters even more confusing, take for example your usual check to see if something is less than, greater to, or equal: 1: int? x = null; 2: int? y = 100; 3:  4: if (x < y) 5: { 6: Console.WriteLine("X is less than Y"); 7: } 8: else if (x > y) 9: { 10: Console.WriteLine("X is greater than Y"); 11: } 12: else 13: { 14: // We fall into the "equals" assumption, but clearly null != 100! 15: Console.WriteLine("X is equal to Y"); 16: } Yes, this code outputs “X is equal to Y” because both the less-than and greater-than operators return false when a Nullable wrapped operator comparable type is null.  This violates a lot of our assumptions because we assume is something is not less than something, and it’s not greater than something, it must be equal.  So keep in mind, that the only two comparison operators that work on Nullable wrapped types where at least one is null are the equals (==) and not equals (!=) operators: 1: int? x = null; 2: int? y = 100; 3:  4: if (x == y) 5: { 6: Console.WriteLine("False, x is null, y is not."); 7: } 8:  9: if (x != y) 10: { 11: Console.WriteLine("True, x is null, y is not."); 12: } Solution: The Nullable static class So we’ve seen that <, <=, >, and >= have some interesting and perhaps unexpected behaviors that can trip up a novice developer who isn’t expecting the kinks that System.Nullable<T> types with comparison operators can throw.  How can we easily mitigate this? Well, obviously, you could do null checks before each check, but that starts to get ugly: 1: if (x.HasValue) 2: { 3: if (y.HasValue) 4: { 5: if (x < y) 6: { 7: Console.WriteLine("x < y"); 8: } 9: else if (x > y) 10: { 11: Console.WriteLine("x > y"); 12: } 13: else 14: { 15: Console.WriteLine("x == y"); 16: } 17: } 18: else 19: { 20: Console.WriteLine("x > y because y is null and x isn't"); 21: } 22: } 23: else if (y.HasValue) 24: { 25: Console.WriteLine("x < y because x is null and y isn't"); 26: } 27: else 28: { 29: Console.WriteLine("x == y because both are null"); 30: } Yes, we could probably simplify this logic a bit, but it’s still horrendous!  So what do we do if we want to consider null less than everything and be able to properly compare Nullable<T> wrapped value types? The key is the System.Nullable static class.  This class is a companion class to the System.Nullable<T> class and allows you to use a few helper methods for Nullable<T> wrapped types, including a static Compare<T>() method of the. What’s so big about the static Compare<T>() method?  It implements an IComparer compatible comparison on Nullable<T> types.  Why do we care?  Well, if you look at the MSDN description for how IComparer works, you’ll read: Comparing null with any type is allowed and does not generate an exception when using IComparable. When sorting, null is considered to be less than any other object. This is what we probably want!  We want null to be less than everything!  So now we can change our logic to use the Nullable.Compare<T>() static method: 1: int? x = null; 2: int? y = 100; 3:  4: if (Nullable.Compare(x, y) < 0) 5: { 6: // Yes! x is null, y is not, so x is less than y according to Compare(). 7: Console.WriteLine("x < y"); 8: } 9: else if (Nullable.Compare(x, y) > 0) 10: { 11: Console.WriteLine("x > y"); 12: } 13: else 14: { 15: Console.WriteLine("x == y"); 16: } Summary So, when doing math comparisons between two numeric values where one of them may be a null Nullable<T>, consider using the System.Nullable.Compare<T>() method instead of the comparison operators.  It will treat null less than any value, and will avoid logic consistency problems when relying on < returning false to indicate >= is true and so on. Tweet   Technorati Tags: C#,C-Sharp,.NET,Little Wonders,Little Pitfalls,Nulalble

    Read the article

  • Which is better : Storing/retrieving images on/from SQL server or in a directory on server

    - by Pankaj Upadhyay
    I am working on a project in Asp.net MVC and need to work with images. There is an SQL database with a Product table. Every product in the table will have it's own image. I have two ways to do this : 1) Save the image in a web directory and store the URL on database. 2) Store the image in SQL itself in binary format and then retrieve it. Which is a better approach ? Mind you, I have no idea how second method works :-P . I will only learn this if there are merits to the second method

    Read the article

< Previous Page | 323 324 325 326 327 328 329 330 331 332 333 334  | Next Page >