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  • How do I dynamically define an instance variable?

    - by Moses
    Hi everyone, I have two classes (class1 and class2) that just store data, no methods. I have a third class that has an instance variable that, depending on some user input, will be set to one of the two classes. So, in the third class I declare the variable generically as NSObject *aClass; and during runtime set it to whatever it should be. aClass = [[Class1 alloc] init]; // or aClass = [[Class2 alloc] init]; However, when I try to access fields from aClass NSString *str = aClass.field1; It gives me the error: request for member 'field1' in something not a structure or a union. Field1 is declared in both class1 and class2. When I try to cast aClass aClass = (Class1 *) aClass; it gives the same error. What am I doing wrong, is there a better way to do this?

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  • Returning EF entities using WCF - Read only web service / public API

    - by alex
    I'm currently migrating an application from Linq-to-SQL & ASP.net Web Services (asmx) to Entity Framework and WCF. My question is, I have a bunch of POCO classes which i have xml mapping files for (for the linq to sql) I've replaced my linq to sql with an entity framework data model I've got an interface - something like IService - that has all the methods on it that i need my service to implement - for example: Product[] GetProductsByKeyword(string keyword); In the above case, Product is a POCO. I now have them as entities within my ef data model - i'm using .net 4, and could take advantage of poco support, but don't really see the need - This service is strictly read only. What's the best way of returning entities in my WCF service? I want it to support other client platforms, not just .net (so php guys could use it)

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  • How to modify posted form data within controller action before sending to view?

    - by Gary
    I want to render the same view after a successful action (rather than use RedirectToAction), but I need to modify the model data that is rendered to that view. The following is a contrived example that demonstrates two methods that that do not work: [AcceptVerbs("POST")] public ActionResult EditProduct(int id, [Bind(Include="UnitPrice, ProductName")]Product product) { NORTHWNDEntities entities = new NORTHWNDEntities(); if (ModelState.IsValid) { var dbProduct = entities.ProductSet.First(p => p.ProductID == id); dbProduct.ProductName = product.ProductName; dbProduct.UnitPrice = product.UnitPrice; entities.SaveChanges(); } /* Neither of these work */ product.ProductName = "This has no effect"; ViewData["ProductName"] = "This has no effect either"; return View(product); } Does anyone know what the correct method is for accomplishing this?

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  • C++ Multiple Inheritance Question

    - by John
    The scenario generating this is quite complex so I'll strip out a few pieces and give an accurate representation of the classes involved. /* This is inherited using SI by many classes, as normal */ class IBase { virtual string toString()=0; }; /* Base2 can't inherit IBase due to other methods on IBase which aren't appropriate */ class Base2 { string toString() { ... } }; /* a special class, is this valid? */ class Class1 : public IBase, public Base2 { }; So, is this valid? Will there be conflicts on the toString? Or can Class1 use Base2::toString to satisfy IBase? Like I say there are lots of other things not shown, so suggestions for major design changes on this example are probably not that helpful... though any general suggestions/advice are welcome.

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  • Which method should I use to give the perception the computer is thinking in programming?

    - by Roy
    I want to create a simple game like tic tac toe where the human user is playing against the computer. The computer function takes a couple of milliseconds to run but I would like to make the computer take 5 seconds to make a move. Which method should I use? 1) Create two memory threads. One for the computer and one for the human user. When the computer is taking 5 seconds to imitate thinking, the human user thread is paused for 5 seconds. 2) Disable input devices for 5 seconds using timer or dispatchertimer 3) Any better methods you can think of Thanks!

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  • Qt: any way to automatically generate QSharedData-based structures?

    - by Eye of Hell
    Hello. Qt has a build-in supprt for creating objects with integrated reference counting via QSharedData and QSharedDataPointer. All wordks great, but for each such object i need to write a lot of code: QSharedData-based implementation class with constructor and copy constructor, object class itsef with accessor methods for each filed. For a simple structures with 5-10 fields this requires really lot of near same code. Is it some ways to automate such classes generation? Maybe it's some generators exists that take a short description and automatically generates implementation class and object class with all accessors?

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  • Method params match signature, but still getting error

    - by Jason
    I am in the midst of converting a VB library to C#. One of my methods has the following signature in VB: Private Shared Sub FillOrder(ByVal row As DataRowView, ByRef o As Order) In C# I converted it to: private static void FillOrder(DataRowView row, ref Order o) From my constructor inside my Order class, I am calling the FillOrder() method like so: DataView dv = //[get the data] if (dv.Count > 0) { FillOrder(dv[0], this); } In VB, this works: Dim dv As DataView = '[get data]' If dv.Count > 0 Then FillOrder(dv.Item(0), Me) End If However, in VS10 in the C# file I am getting a red squiggle under this call with the following error: The best overloaded method match for [the method] has some invalid arguments This was working code in VB. What am I doing wrong?

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  • Seam + hibernate + jsf on weblogic

    - by Kiva
    I'm making a little project with Seam, Hibernate and JSF. This project run on JBoss 5.1. My boss wants to deploy this project on WebLogic. I read on the seam documentation that seam and WebLogic don't work fine together. I would like to know if I can use Hibernate (with JPA) and JSF on WebLogic and what framework (struts, spring?) I can use to replace Seam. Edit: I read in the seam documentation (chapter 39, weblogic integration) and I find that: For several releases of Weblogic there has been an issue with how Weblogic generates stubs and compiles EJB's that use variable arguments in their methods. This is confirmed in the Weblogic 9.X and 10.0.MP1 versions. Unfortunately the 10.3 version only partially addresses the issue as detailed below. So, I want to know if other problems like this exist. Edit 2: I use Weblogic 10.3

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  • Using Linq to SQL change events with attribute-based mapping

    - by R Mene
    I'm writing a new ASP.NET MVC2 application using Linq to SQL. This application depends on an existing SQL database. I am using attribute-based mapping to map my database fields to my Linq to SQL entities. I also need to make use of Linq to SQL's On[Property]Changed methods so I can perform change-auditing of database tables within my application. Whereas the documentation explains how to do this when using Linq to SQL's ORM and dbml files (i.e. by writing partial classes), it is not clear how to do with when using attribute-based mapping or when using XML-based mapping. It would be very helpful if someone could describe how to do this.

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  • Would you make this method Static or not?

    - by Adam Drummond
    During a code review I presented a method quickly to the team that I had made static and one person agreed that there was no reason for it to not be static and a person disagreed saying that he would not make it static because it wasn't necessary and just to be on the safe side for future modifications and testing. So I did quite a bit of research and obviously it's a specialized case but I would like to know what you would do in this situation and why? (Its basically a helper method I call from a few different methods, a very low traffic page. More for my knowledge and learning on Static.) private IEnumerable<Category> GetCategoryByID(int id, Context context) { var categoryQuery = from selectAllProc in context.SelectAll_sp() where selectAllProc.CategoryID == id select selectAllProc; return categoryQuery; }

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  • Which would be better? Storing/access data in a local text file, or in a database?

    - by TerranRich
    Basically, I'm still working on a puzzle-related website (micro-site really), and I'm making a tool that lets you input a word pattern (e.g. "r??n") and get all the matching words (in this case: rain, rein, ruin, etc.). Should I store the words in local text files (such as words5.txt, which would have a return-delimited list of 5-letter words), or in a database (such as the table Words5, which would again store 5-letter words)? I'm looking at the problem in terms of data retrieval speeds and CPU server load. I could definitely try it both ways and record the times taken for several runs with both methods, but I'd rather hear it from people who might have had experience with this. Which method is generally better overall?

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  • Securing an ajax request

    - by asdasdsa
    i have a website that uses session cookies for security. it works fine and all, but any ajax requests right now are not secure. example being lets say a user is on a page. they can only get to this page if they are logged in with a session - so far so good. but now the ajax request they ask for is ajaxpages/somepage.php?somevar=something&anothervar=something if any other user decides to just go to that link themselves (without a session) they still get the same ajax output that was meant for logged in people. so obviously im going to have to pass session data across when i send an ajax request. anyone have any tips for the best way of doing this? ive never done this before and would rather use trusted methods than make up my own.

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  • class method as hash value

    - by demas
    I have this working code: class Server def handle(&block) @block = block end def do @block.call end end class Client def initialize @server = Server.new @server.handle { action } end def action puts "some" end def call_server @server.do end end client = Client.new client.call_server My Server will handle more then one action so I want to change code such way: class Server def handle(options) @block = options[:on_filter] end def do @block.call end end class Client def initialize @server = Server.new my_hash = { :on_filter => action } @server.handle(my_hash) end def action puts "some" end def call_server @server.do end end client = Client.new client.call_server It is incorrect code because action() method calls on create my_hash, but if I try to modify code to: my_hash = { :on_filter => { action } } i get error message. Is it possible to create hash with methods as hash values ?

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  • What is the best method of assessment for computer science students?

    - by Gavimoss
    This question is a bit more philosophical so feel free to remove if you like but it's been bugging me for the last 4 years! As a final year student I find that exams can be often be passed with a couple of days of cramming, without necessarily retaining or understanding the content i.e. a regurgitation of lecture notes is often enough to gain high marks. A friend of mine is about to graduate with an honours degree whose final year evaluation was based solely on practical work (a project, assignment marks and the creation of a poster) yet all of this work could have been completed by a third party. Personally I don't think either of these methods of assessment is sufficient as I am currently on track for a 1st class honours in artificial intelligence and computer science and believe this is mostly due to my skill in passing exams not my skill as a programmer or my vast in depth knowledge of any of the subjects I have "studied". Surely there is a better way to assess our skills - isn't there?

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  • Python OpenGL Can't Redraw Scene

    - by RobbR
    I'm getting started with OpenGL and shaders using GLUT and PyOpenGL. I can draw a basic scene but for some reason I can't get it to update. E.g. any changes I make during idle(), display(), or reshape() are not reflected. Here are the methods: def display(self): glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT ) glMatrixMode(GL_MODELVIEW) glLoadIdentity() glUseProgram(self.shader_program) self.m_vbo.bind() glEnableClientState( GL_VERTEX_ARRAY ) glVertexPointerf(self.m_vbo) glDrawArrays(GL_TRIANGLES, 0, len(self.m_vbo)) glutSwapBuffers() glutReportErrors() def idle(self): test_change += .1 self.m_vbo = vbo.VBO( array([ [ test_change, 1, 0 ], # triangle [ -1,-1, 0 ], [ 1,-1, 0 ], [ 2,-1, 0 ], # square [ 4,-1, 0 ], [ 4, 1, 0 ], [ 2,-1, 0 ], [ 4, 1, 0 ], [ 2, 1, 0 ], ],'f') ) glutPostRedisplay() def begin(self): glutInit() glutInitWindowSize(400, 400) glutCreateWindow("Simple OpenGL") glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB) glutDisplayFunc(self.display) glutReshapeFunc(self.reshape) glutMouseFunc(self.mouse) glutMotionFunc(self.motion) glutIdleFunc(self.idle) self.define_shaders() glutMainLoop() I'd like to implement a time step in idle() but even basic changes to the vertices or tranlastions and rotations on the MODELVIEW matrix don't display. It just puts up the initial state and does not update. Am I missing something?

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  • How to use intent between tabs in java/Android?

    - by Praveen Chandrasekaran
    I would need to know how to handle the intent between tabs. For example, I have a tab activity with two tabs. First on content is a text view. another one is a map view. When i click that text view it redirects to the tab2. it can be easily achieved by setCurrentTab(1) or setCurrentTabByTag("tab2") methods. But i want to pass lat and long values to that Map Activity to drop pin. What is the better way to use intents or getter/setter in java? What do you prefer? if your answer is "Intents". How?

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  • Is it ok to store large objects (java component for example) in an Application variable?

    - by DustMason
    I am developing an app right now which creates and stores a connection to a local XMPP server in the Application scope. The connection methods are stored in a cfc that makes sure the Application.XMPPConnection is connected and authorized each time it is used, and makes use of the connection to send live events to users. As far as I can tell, this is working fine. BUT it hasn't been tested under any kind of stress. My question is: Will this set up cause problems later on? I only ask because I can't find evidence of other people using Application variables in this way. If I weren't using railo I would be using CF's event gateway instead to accomplish the same task.

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  • Casting objects to Integer,string ,...

    - by Milan
    Hello everybody! I have one small problem. I have list of types(int,string,..) ArrayList<Class> typeList; and I have some input values; ArrayList<Object> values; How to cast some value to some type if I know which type from the typeList is the values; typeList.get(i).cast(values.get(i)); <- this is not working??? Actualy I generate dynamic form in runtime. With Java reflection I get parameterTypes from methods from some class, I generate form with input fields and then i want to cast the text from the input fields to specific types from the paramterTypes that I got with Java reflection from some class.

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  • Tracing all events in VB.NET

    - by MatsT
    I keep running into situations where I don't know what event I have to listen to in order to execute my code at the correct time. Is there any way to get a log of all events that is raised? Any way to filter that log based on what object raised the event? EDIT: Final solution: Private Sub WireAllEvents(ByVal obj As Object) Dim parameterTypes() As Type = {GetType(System.Object), GetType(System.EventArgs)} Dim Events = obj.GetType().GetEvents() For Each ev In Events Dim handler As New DynamicMethod("", Nothing, parameterTypes, GetType(main)) Dim ilgen As ILGenerator = handler.GetILGenerator() ilgen.EmitWriteLine("Event Name: " + ev.Name) ilgen.Emit(OpCodes.Ret) ev.AddEventHandler(obj, handler.CreateDelegate(ev.EventHandlerType)) Next End Sub And yes, I know this is not a good solution when you actually want to do real stuff that triggers off the events. There are good reasons for the 1 method - 1 event approach, but this is still useful when trying to figure out which of the methods you want to add your handlers to.

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  • Re-ordering a collection of UIView's based on their CGPoint

    - by Chris
    Hi all, I have a NSMutableArray that holds a collection of UIViewControllers Amongst other properties and methods an instance of each of the viewControllers are placed in a parent view The user will place these objects individually when desired to. So essentially I use - (void)addSubview:(UIView *)view when a new view is added to the parent view controller. Because the UI is isometric it's made things a tad more complicated What I am trying to do is re-order the views based on their co-ordinate position, so items higher up the parent UIView frame is indexed lower then views lower in the parent UIview frame. And items that are on the left side of the view are positioned at a higher index to those on the right I think the solution may have to do with re-ordering the NSMutableArray but how can I compare the CGpoints? Do I need to compare the x and y separately?

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  • Pattern for iPhone background loading during init?

    - by Rob S.
    Hi everyone, I'm currently kicking off a background thread to do some REST queries in my app delegate's didFinishLaunchingWithOptions. This thread creates some objects and populates the model as the rest of the app continues to load (because I don't block, and didFinishLaunchingWithOptions returns YES). I also put up a loading UIViewController 'on top' of the main view that I tear down after the background initialization is complete. My problem is that I need to notify the first view (call it the Home view) that the model is ready, and that it should populate itself. The trick is that the background download could have finished before Home.viewDidAppear is called, or any of the other Home.initX methods. I'm having difficulty synchronizing all of this and I've thought about it long enough that it feels like I'm barking up the wrong tree. Are there any patterns here for this sort of thing? I'm sure other apps start by performing lengthy operations with loading screens :) Thanks!

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  • How do I combine similar method calls into a delegate pattern?

    - by Daniel T.
    I have three methods: public void Save<T>(T entity) { using (new Transaction()) { Session.Save(entity); } } public void Create<T>(T entity) { using (new Transaction()) { Session.Create(entity); } } public void Delete<T>(T entity) { using (new Transaction()) { Session.Delete(entity); } } As you can see, the only thing that differs is the method call inside the using block. How can I rewrite this so it's something like this instead: public void Save<T>(T entity) { TransactionWrapper(Session.Save(entity)); } public void Create<T>(T entity) { TransactionWrapper(Session.Create(entity)); } public void Save<T>(T entity) { TransactionWrapper(Session.Save(entity)); } So in other words, I pass a method call as a parameter, and the TransactionWrapper method wraps a transaction around the method call.

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  • Keeping Computer Science Writing Accessible and Eloquent

    - by Federer
    This question is particularly aimed at descriptions and explanations of what is happening in a computer program, as well as any general advice or approaches for undertaking technical reports in Computer Science at both undergraduate and graduate levels. You see, I am having particular difficulty in the best way to explain what is happening. As in, given any given program from a multi-agent system to a standard webservice, the best and most eloquent way to say exactly what is going on, the logic behind it and it's respective justifications. Should I avoid saying class names? Avoid specifying methods? Keep referring to class variables and any particular references? I'm banging my head against the wall at trying to keep a solid technical foundation and making it accessible to people of all backgrounds. Apologies for the rather vague question. Cheers.

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  • Create a select tag with some options grouped and others not grouped

    - by dontangg
    I'm using Rails 3. I want to create a select tag with some options grouped and others not grouped. Options would look something like this: Income Auto Fuel Maintenance Home Maintenance Mortgage In this example, Income is not a group, but Auto and Home are. I see three helper methods grouped_options_for_select and grouped_collection_select, option_groups_from_collection_for_select. Is there a way to use a helper to do this or will I have to generate the HTML myself? I imagine I could use two different helpers to create the options and just append the results of both.

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  • In java can i have more than one class/object in a file?

    - by David
    So the way i've been told to do things is you have your file and the file name is Classname.java and then the code is something like this: class ClassName { SOME METHODS main {} } and then thats all. I'd like to have two objects defined and used within the same .java file. (i don't want to have to put the other class in a difernt file just because i'd like to send this to someone and i want to avoid hasstle of atatching multiple files to an email [the lazy do make good programers though if you think about it]) is it possible to do this? do i have to do anything special and if so what? what are some mistakes i'm likely to make or that you have made in the past when doing this?

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