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  • LINQ query checks for null

    - by user300992
    I have a userList, some users don't have a name (null). If I run the first LINQ query, I got an error saying "object reference not set to an instance of an object" error. var temp = (from a in userList where ((a.name == "john") && (a.name != null)) select a).ToList(); However, if I switch the order by putting the checking for null in front, then it works without throwing any error: var temp = (from a in userList where ((a.name != null) && (a.name == "john")) select a).ToList(); Why is that? If that's pure C# code (not LINQ), I think both would be the same. I don't have SQL profiler, I am just curious what will be the difference when they are being translated on SQL level.

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  • xml intellisense with Eclipse Europa?

    - by Maddy.Shik
    Please suggest some free tools or some in build feature in Eclipse for intellisense of xml. I am using Eclipse Europa which is for EE java developers. <?xml version ="1.0" encoding = "UTF-8"?> <tests xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="http://jtestcase.sourceforge.net/dtd/jtestcase2.xsd"> </tests> Xml code above is part of xml file i am working upon. I am expecting eclipse to suggest me tags based upon xsd specified above. I am using ctrl+space for suggestion of new tag. Please suggest if i am using wrong key for intellisense or am i missing some tool or plugin. Thanks

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  • How do I obtain a new stateful session bean in a servlet thread?

    - by FarmBoy
    I'm experimenting with EJB3 I would like to inject a stateful session bean into a servlet, so that each user that hits the servlet would obtain a new bean. Obviously, I can't let the bean be an instance variable for the servlet, as that will be shared. And apparantly injecting local variables isn't allowed. I can use the new operator to create a bean, but that doesn't seem the right approach. Is there a right way to do this? It seems like what I'm trying to do is fairly straightforward, after all, we would want each new customer to find an empty shopping cart.

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  • Empty accessors do matter? Regarding value types and their modification

    - by Petr
    Hi, I have following code that does not work due to "a" being a value typed. But I thought it would not work even without accessors, but it did: class Program { a _a //with accessors it WONT compile { get; set; } static void Main(string[] args) { Program p = new Program(); p._a.X = 5; //when both accessors are deleted, compiler does not //complain about _a.X not being as variable } } struct a { public int X; } It does not work as "a" is struct. But when I delete accessors from "_a" instance, it works. I do not understand why. Thanks

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  • GWT and Panda Video Converter

    - by Maksim
    I'm writing GWT application where I need to upload video file and encode that video into different video formats. I've decided to use Panda Video Converter. I was able to run panda on my EC2 instance (using their image) and I can upload video from Panda's test pages but now I'm trying to make same thing with my own application in GWT. The question that I have is: How do I get Video id and how do I post my video to the server. What URL do I need to use for that? I tried to read their documentation but have no clue where to start. This is my fist time working with webservices and url, probably that's why I don't how it works.

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  • Setting Sql server security rights for multiple situations

    - by DanDan
    We have an application which uses an instance of Sql Server locally for its backend storage. The administrator windows login has had its sysadmin right revoked, and instead two sql logins have been created; one for the application with a secret password and one read only login we let users view the raw data with. This was working fine until we moved on FileStreams, which requires intergrated windows authentication. So now the sql server logins must be replaced. As a result, I am now reviewing all of our logins but I am not sure how it is possible. It seems that the application needs full read/write access, yet I still need to lock down writing to the tables so the user cannot login into the database and delete data randomly. Does anyone have any tips for setting multiple levels of security using intergrated windows logins, or can you direct me to any further reading? Some answers can also be found on serverfault: http://serverfault.com/questions/138763/setting-sql-server-security-rights-for-multiple-situations

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  • Get XAML from WPF Custom RichTextFormat

    - by Erika
    I've looked at other posts, but i cant seem to find something that works. I have a custom control WPF RichTextBox and would like to obtain the XAML from this control. I have tried the following //rt is the name of this particular custom richtextbox TextRange range = new TextRange(rt.Document.ContentStart, rt.Document.ContentEnd); MemoryStream stream = new MemoryStream(); range.Save(stream, DataFormats.Xaml); string xamlText = Encoding.UTF8.GetString(stream.ToArray()); return xamlText; but this doesnt seem to work :s I can access the rt.Document.Content start etc but it seems to crash there "Object Reference not set to instance of an object". I am using the richtextbox directly from the .xaml.cs so it should be initiated and so on :s. Any Ideas or other ways to get the XAML from a richtextbox pls? (i'm requiring the XAML cos i actually want to get the HTML.. if theres some other direct manner perhaps?)

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  • Multiple MCs, Single Listener, AsBroadcaster

    - by Brett
    I'm currently working trying to have multiple MCs inside a container MC which when they mini MCs are clicked will broadcast a message so that I can act upon them. This would be simple in AS 3 as it would be mc.addEventListener(MouseEvent.CLICK, obj); however, this is AS 2 and so I am semi-forced to use the broadcastMessage('myMessage'); and mc.addListener(obj); event handler. The main problem is that the broadcaster isn't broadcasting any messages. The second problem is that there are 5 MCs and when I click one of them, I get 5 trace messages about the click. I can't seem to keep the MC clicks unique even though they are all given separate instance names vie the properties panel. Any help would be appreciated. A link to my code is here (pastie.org #481511). Can you see anything wrong?

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  • .NET: Type.Parse not working?

    - by Rosarch
    What am I doing wrong? using System; using System.Collections.Generic; using System.Linq; using System.Text; using Microsoft.Xna.Framework.Graphics; using Box2D.XNA; //... Type.Parse("GameObjectModel"); Compilation error: 'System.Type' does not contain a definition for 'Parse' I am trying to get the type of a class name from a string, so I can instantiate an instance of that class.

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  • Help me with a solution for what could be solutioned by virtual static fields... in FPC

    - by Gregory Smith
    Hi I'm doing an event manager in Freepascal Each event is an object type TEvent (=object), each kind of event must derive from this class. Events are differentiated by an integer identificator, assigned dynamically. The problem is that i want to retrieve the event id of an instance, and i can't do it well. All instances of a class(object) have a unique id = so it should be static field. All classes have a diferent id = so it should be virtual. Event ids are assignated in run time, and can change = so it can't be a simple method In sum, I can't put all this together. I'm looking for an elegant solution, i don't want to write a hardcoded table, actualizing it in every constructor... etc, i'd prefer something taking advantage of the polymorphism Can anyone help me with another technical or design solution? I remark I don't want to use class instead of object construct.(property doesn't work on objects? :(

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  • Cannot Debug Visual Basic 6 ActiveX Component On 64-bit OS

    - by Humanier
    Hi, The situation might sound a bit weird but I have to play with what I have. There's a Win2003 64-bit server OS and a legacy application written using Visual Studio 6. The app consists of two parts: ActiveX components written in VB6 and C++ code which uses them. I need to debug the components' code. I installed Visual Studio 6 on the server and I'm able to step into the component's code. Then I got following situation: 1) C++ code works until it needs to instantiate component A. 2) At this step we switch to VB6 and start debugging Component's A. 3) In the very beginning component A creates an instance of a class C exposed by component B. At this step VB6 debugger shows error message with title "OLEDB32.DLL" and following text: "Failed to load resource DLL C:\Program Files (x86)\Common Files\System\Ole DB\OLEDB32R.DLL" Additional information: The last step in initialization of the class C is opening an ADO connection to SQL server using OLEDB provider. I'd appreciate any ideas on how resolve this problem. Thanks in advance.

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  • Mutex names - best practice?

    - by Argalatyr
    Related to this question, what is the best practice for naming a mutex? I realize this may vary with OS and even with version (esp for Windows), so please specify platform in answering. My interest is in Win XP and Vista. EDIT: I am motivated by curiousity, because in Rob Kennedy's comment under his (excellent) Answer to the above-linked Question, he implied that the choice of mutex name is non-trivial and should be the subject of a separate question. EDIT2: The referenced question's goal was to ensure only a single instance of an app is running.

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  • How to change line thickness in iText?

    - by drasto
    I'm drawing images to pdf using Java framework iText. I need to draw lines of specified width. There is a method setLineWidth(float width) in class PdfContentByte that should change it. However no matter what value I pass as its parameter the lines drawn are always extra thin. There is following line in javadoc of setLineWidth: The line width specifies the thickness of the line used to stroke a path and is measured in user space units. I don't know what is "space unit". Everything else in iText seems to be measured in point(around 1/72 inch). I cant find any reference to what are those "space units" and how to change them. code: to.setLineWidth(thickness); to.moveTo(x, y); to.lineTo(x + 100, y + 100); Variable to contains instance of PdfContentByte.

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  • Should Java IOException have been an unchecked RuntimeException?

    - by Derek Mahar
    Do you agree that the designers of Java class java.io.IOException should have made it an unchecked run-time exception derived from java.lang.RuntimeException instead of a checked exception derived only from java.lang.Exception? I think that class IOException should have been an unchecked exception because there is little that an application can do to resolve problems like file system errors. However, in When You Can't Throw An Exception, Elliotte Rusty Harold claims that most I/O errors are transient and so you can retry an I/O operation several times before giving up: For instance, an IOComparator might not take an I/O error lying down, but — because many I/O problems are transient — you can retry a few times, as shown in Listing 7: Is this generally the case? Can a Java application correct I/O errors or wait for the system to recover? If so, then it is reasonable for IOException to be checked, but if it is not the case, then IOException should be unchecked so that business logic can delegate handling this exception to a separate system error handler.

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  • Null Reference Exception on MVVM pattern

    - by Mohit Deshpande
    System.NullReferenceException Object reference not set to an instance of an object. at Microsoft.Windows.Design.DocumentModel.Trees.MarkupDocumentTreeManager.<FindMarkupNodePath>d__0.MoveNext() at System.Linq.Enumerable.FirstOrDefault[TSource](IEnumerable1 source) at MS.Internal.Services.DocumentInformationServiceImpl.get_Root() at MS.Internal.Designer.VSDesigner.Load() at MS.Internal.Designer.VSIsolatedDesigner.VSIsolatedView.Load() at MS.Internal.Designer.VSIsolatedDesigner.VSIsolatedDesignerFactory.Load(IsolatedView view) at MS.Internal.Host.Isolation.IsolatedDesigner.BootstrapProxy.LoadDesigner(IsolatedDesignerFactory factory, IsolatedView view) at MS.Internal.Host.Isolation.IsolatedDesigner.BootstrapProxy.LoadDesigner(IsolatedDesignerFactory factory, IsolatedView view) at MS.Internal.Host.Isolation.IsolatedDesigner.Load() at MS.Internal.Designer.DesignerPane.LoadDesignerView() I keep getting this exception and then intellisense stops working in a XAML text editor. Any ideas why?

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  • Entity framework and many to many queries unusable?

    - by John Landheer
    I'm trying EF out and I do a lot of filtering based on many to many relationships. For instance I have persons, locations and a personlocation table to link the two. I also have a role and personrole table. EDIT: Tables: Person (personid, name) Personlocation (personid, locationid) Location (locationid, description) Personrole (personid, roleid) Role (roleid, description) EF will give me persons, roles and location entities. EDIT: Since EF will NOT generate the personlocation and personrole entity types, they cannot be used in the query. How do I create a query to give me all the persons of a given location with a given role? In SQL the query would be select p.* from persons as p join personlocations as pl on p.personid=pl.personid join locations as l on pl.locationid=l.locationid join personroles as pr on p.personid=pr.personid join roles as r on pr.roleid=r.roleid where r.description='Student' and l.description='Amsterdam' I've looked, but I can't seem to find a simple solution.

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  • Code to apply expression tree directly to List

    - by Gamma Vega
    Is there a method call in Linq that will apply a expression tree directly on a List<V>? For instance, if I have a expression tree that is built on Order type, and i have a collection of List<Order> items on which i need to apply this expression. I am looking something similar to: class OrderListStore : IQueryable<V>, <other interfaces required to implement custom linq provider> { List<Order> orders; public Expression Expression { get { return Expression.Constant(this); } } IEnumerator<V> IEnumerable<V>.GetEnumerator() { //Here I need to have a method that will take the existing expression //and directly apply on list something like this .. Expression.Translate(orders); } } Any help in this regard is highly appreciated.

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  • Loop through all subclasses in an Android view?

    - by Slapout
    I’m working on a game for Android. To help implement it, my idea is to create a subclass of a view. I would then insert several instances of this class as children of the main view. Each instance would handle detecting when it was pressed (via OnTouchListener). The problem I’m having now is how do I loop through all these sub-views so I can read their statuses and process them? (I.e. when they all reach a certain state something should happen). Or is there a better way to have several objects on the screen that respond to touch and whose status I can check?

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  • Java Logger with Servlets

    - by Sunny
    Hi Guys, I am using a wrapper class A which initializes the java.util.logger static class A { public static Logger logger; public static void init(){ logger = Logger.getLogger("test"); } Now, everywhere in my program I call A.init() and then logger.log("Message+uniqid"). But recently I moved to HTTP servlets and I am having problems. Basically, If a app is already running and the logger is logging... and someone else runs the app again, the logger from the previous instance stops and starts logging for the second one. Can anyone have a solution to how I should go about fixing this static variable issue? I can pass the logger into all constructor classes but thats really tedious. Any better solution would be appreciated..

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  • A quick design question about C++ container classes in shared memory

    - by recipriversexclusion
    I am writing a simple wrapper around boost::interprocess's vector container to implement a ring buffer in shared memory (shm) for IPC. Assume that buf is an instance of RingBuffer created in shm. Now, in its ctor, buf itself allocates a private boost::interprocess::vector data member to store values, e.g. m_data. My question is: I think m_data should also be created in shared memory. But it this a necessity? What happens if buf that was created in shm itself, allocates standard memory, i.e. using new. Does this get allocated on the calling process's heap? I don't think buf is allocated there so how come a data member that is private to an object not on a process's heap gets allocated there. I'm confused.

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  • How to scale MySQL with multiple machines?

    - by erotsppa
    I have a web app running LAMP. We recently have an increase in load and is now looking at solutions to scale. Scaling apache is pretty easy we are just going to have multiple multiple machines hosting it and round robin the incoming traffic. However, each instance of apache will talk with MySQL and eventually MySQL will be overloaded. How to scale MySQL across multiple machines in this setup? I have already looked at this but specifically we need the updates from the DB available immediately so I don't think replication is a good strategy here? Also hopefully this can be done with minimal code change. PS. We have around a 1:1 read-write ratio.

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  • boost pool_alloc

    - by mr grumpy
    Why is the boost::fast_pool_allocator built on top of a singleton pool, and not a separate pool per allocator instance? Or to put it another way, why only provide that, and not the option of having a pool per allocator? Would having that be a bad idea? I have a class that internally uses about 10 different boost::unordered_map types. If I'd used the std::allocator then all the memory would go back to the system when it called delete, whereas now I have to call release_memory on many different allocator types at some point. Would I be stupid to roll my own allocator that uses pool instead of singleton_pool? thanks

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  • Change NSNumber value by allocating new NSNumber?

    - by Peter Hajas
    I understand that NSNumber is immutable, but I still have the need to change it in my app. I use it because it's an object, and therefore usable with @property (if I could, I would use float or CGFloat in a heartbeat, but sadly, I can't). Is there any way to just overwrite the old NSNumber instance? I'm trying this: NSNumber *zero = [[NSNumber alloc] initWithFloat:0.0]; myNSNumber = zero but this doesn't change the value. This is a simplified version of my code, as I'm changing the root view controller's parameter (I know, not MVC-friendly). Still, the changing of the value should be the same assignment, right? Should I release myNSNumber first? What should I set the @property at for myNSNumber? Thanks!

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  • Detecting if the user selected "All Users" or "Just Me" in a Custom Action

    - by Ben
    Hi, I'm trying to detect if the user has selected the "All Users" or the "Just Me" radio during the install of my program. I have a custom action setup that overrides several methods (OnCommit, OnBeforeInstall, etc.). Right now I'm trying to find out this information during OnCommit. I've read that the property I want to get at is the ALLUSERS property, but I haven't had any luck finding where it would be stored in instance/local data. Does anyone know of a way to get at it? -Ben

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  • opengl invert framebuffer pixels

    - by ToxIk
    I was wondering was the best way to invert the color pixels in the frame buffer is. I know it's possible to do with glReadPixels() and glDrawPixels() but the performance hit of those calls is pretty big. Basically, what I'm trying to do is have an inverted color cross-hair which is always visible no matter what's behind it. For instance, I'd have an arbitrary alpha mask bitmap or texture, have it render without depth test after the scene is drawn, and all the frame buffer pixels under the masked (full alpha) pixels of the texture would be inverted. I've been trying to do this with a texture, but I'm getting some strange results, also all the blending options I still find confusing.

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