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• Is select() Ok to implement single socket read/write timeout ?

  - by chmike

  I have an application processing network communication with blocking calls. Each thread manages a single connection. I've added a timeout on the read and write operation by using select prior to read or write on the socket. Select is known to be inefficient when dealing with large number of sockets. But is it ok, in term of performance to use it with a single socket or are there more efficient methods to add timeout support on single sockets calls ? The benefit of select is to be portable.

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• What is a good way of coding a file processing program, which accepts multisource data in Java

  - by jjepsuomi

  I'm making a data prosessing system, which currently is using csv-data as input and output form. In the future I might want to add support for example database-, xml-, etc. typed input and output forms. How should I desing my program so that it would be easy to add support for new type of data sources? Should simply make for example an abstract data class (which would contain the basic file prosessing methods) and then inherit this class for database, xml, etc. cases? Hope my question is clear =) In other words my question is: "How to desing a file prosessing system, which can be easily updated to accept input data from different sources (database, XML, Excel, etc.)".

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• What is the time taken by java to call a method in another package?

  - by satish

  I have an assignment where i need to do feasibility study on two of my approaches and find optimized one. There are two packages A and B User input is gathered in A and then sent to B for execution. Now my approaches are 1. Call B methods from package A one by one. 2. Create a common method in B and send all the input as parameters. Which is feasible and best one, I know 2 is good in terms of code optimization and less number of calls. But, I want to understand what will be the execution time difference in above approaches How much time does java take to call method in another package? Is there any default value like x nano seconds or y milli seconds. Based on the time taken I can choose the appropiate one. Thanks

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• C# - How to convert 10 bytes to unsigned long

  - by Justin

  Hey, I have 10 bytes - 4 bytes of low order, 4 bytes of high order, 2 bytes of highest order - that I need to convert to an unsigned long. I've tried a couple different methods but neither of them worked: Try #1: var id = BitConverter.ToUInt64(buffer, 0); Try #2: var id = GetID(buffer, 0); long GetID(byte[] buffer, int startIndex) { var lowOrderUnitId = BitConverter.ToUInt32(buffer, startIndex); var highOrderUnitId = BitConverter.ToUInt32(buffer, startIndex + 4); var highestOrderUnitId = BitConverter.ToUInt16(buffer, startIndex + 8); return lowOrderUnitId + (highOrderUnitId * 100000000) + (highestOrderUnitId * 10000000000000000); } Any help would be appreciated, thanks!

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• Migrating Data to MSSQL 2008

  - by Fred Clown

  I am trying to migrate data from an Informix database to MSSQL 2008. I've got quite a lot of data to move. I've been try multiple methods to get the data over, and so far SQLBulkCopy in multiple chunks seems to be the fastest that I can find. Does anyone know of a faster means of getting the data over? I'm trying to cut down on the transfer time so that on my cut-over date I don't run out of time to do the full cut-over. Thanks.

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• WSAT Security tab error for Custom Role provider

  - by shesb

  I have created custome Membership Role and Profile provider using INGRES db. Now I can see my IngresMembership and IngresRole provider in the Provider tab(Select a different provider for each feature (advanced) ) of WSAT but when I clik on security tab I get this error: "There is a problem with your selected data store. This can be caused by an invalid server name or credentials, or by insufficient permission. It can also be caused by the role manager feature not being enabled. Click the button below to be redirected to a page where you can choose a new data store. The following message may help in diagnosing the problem: Object reference not set to an instance of an object." What am I missing? Do I need to add code for all override methods for Role provider? I have just written code for the Initialize and GetRolesForUser functions. Thanks

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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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• API verbs for an interruptible operation

  - by 280Z28

  I have a long running task as part of my application. The task can be started, paused, resumed, and cancelled. I'm trying to find the best interface for these operations. Two seem clear: Pause and Cancel. This leaves the start and resume operations. I could include both Start and Resume. This has the downside of either requiring the API consumer to check the state before starting/resuming the operation to call the right method, or making the methods aliases of each other. I'm thinking I should include either Start or Resume, but I don't know which one is the most appropriate. Does anyone have any examples in the .NET Framework of such behavior? I prefer to follow established patterns whenever they are available.

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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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• response.sendRedirect - check redirect is up

  - by Trick

  From JSP I just want a redirect to another page... <% response.sendRedirect("http://www.google.com/"); %> Can I check if google.com is up and then redirect (or write a msg else)... Something like that: <% if(ping("www.google.com")) { response.sendRedirect("http://www.google.com/"); } else { // write a message }%> Or <% try { response.sendRedirect("http://www.google.com/"); } catch(SomeException e) { // write a message }%> It is just an JSP page, I don't have any libraires available (like ApacheCommons for http GET methods).

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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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• 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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• Jquery/CSS help needed to make fallback for IE and older browsers

  - by matt_50

  Wondering if any of you can help me: I've made a signup modal that uses a CSS transform to switch between two methods of signing up. I've decided to try a 'card flip' type effect. Have a look at this JSfiddle in any browser that supports CSS 3D transforms - click the 'old fashioned way' text to 'flip' the modal (simplified for demo purposes): http://jsfiddle.net/voodoo6/cnTMz/8/ Then take a look in IE8/9 - as the 'back' is taller than the front and IE does;t support 'backface-visibility: hidden;' the reverse can be seen below the front. I've been trying to use JQuery and conditional CSS to 'display:none' the 'back' on load in IE (and older browsers), then add a 'display:block;' class to show it on click, problem is, I'm a JQuery beginner and have been struggling to get it to work! Not even sure if this is the best approach? Can anybody suggest an approach that would get this working in less-capable browsers? Thanks for any advice..

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• gwt - Using List<Serializable> in a RPC call?

  - by Garagos

  I have a RPC service with the following method: public List<Serializable> myMethod(TransactionCall call) {...} But I get a warning when this method is analyzed, and then the rpc call fails Analyzing 'my.project.package.myService' for serializable types Analyzing methods: public abstract java.util.List<java.io.Serializable> myMethod(my.project.package.TransactionCall call) Return type: java.util.List<java.io.Serializable> [...] java.io.Serializable Verifying instantiability (!) Checking all subtypes of Object wich qualify for serialization It seems I can't use Serializable for my List... I could use my own interface instead (something like AsyncDataInterface, wich implements the Serializable interface) but the fact is that my method will return a list custom objects AND basic objects (such as Strings, int....). So my questions are: Is it a standart behaviour? (I can't figure out why I can't use this interface in that case) Does anyone have a workaround for that kind of situation?

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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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• strcat() won't exit

  - by Tristan Sebens

  I'm trying to implement a very basic server in C, one part of which is constructing HTTP headers. To do this I have written a class called header_builder, which basically constructs the headers for me. One of the most basic methods of this class is append_header_line, shown below: void append_header_line( const char *line, char *hdr ) { printf("Adding header line\n"); strcat( hdr, line ); printf("Line added. Adding ending.\n"); strcat( hdr, "\r\n" ); printf("Success\n"); } All it's supposed to do is tack the "line" parameter onto the end of the "hdr" parameter, and then add "\r\n" to the end of it all. The problem is that the first strcat call never exits. When I run this code, all it does is say: Adding header line Which means that the following lines never execute, and I can't figure out why. Any thoughts?

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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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• 3D Camera looking at arbitrary point, but never rolling to do so

  - by Nektarios

  (In C#/XNA 4.0) I have Vector3 cameraPosition, Vector3 targetPosition I want to have my camera look at the target, always 'facing' it, but never rolling So roll always is neutral, to view the target the camera always either adjusts pitch or yaw I've tried countless combinations of methods and information I find here and on the web but I haven't found anything that works properly. I think my issue may be my 'Up' vector (which I've tried .Up, 1,0,0, 0,1,0, 0,0,1) When I move my camera I do: CameraPosition += moveSpeed * vectorToAdd; UpdateViewMatrix(); UpdateViewMatrix() is.. well, I've tried everything I have seen. At most simple... View = Matrix.CreateLookAt(CameraPosition, targetPosition, upVector); Where upVector has been Vector3.Up, 1, 0, 0; 0, 1, 0; 0, 0, 1, or other more 'proper' attempts to get my actual up vector. This sounds like it's probably my problem.. This should be dead simple, help!

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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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• 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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• ArrayBlockingQueue exceeds given capacity

  - by Wojciech Reszelewski

  I've written program solving bounded producer & consumer problem. While constructing ArrayBlockingQueue I defined capacity 100. I'm using methods take and put inside threads. And I've noticed that sometimes I see put 102 times with any take's between them. Why does it happen? Producer run method: public void run() { Object e = new Object(); while(true) { try { queue.put(e); } catch (InterruptedException w) { System.out.println("Oj, nie wyszlo, nie bij"); } System.out.println("Element added"); } } Consumer run method: public void run() { while(true) { try { queue.take(); } catch (InterruptedException e) { e.printStackTrace(); } System.out.println("Element removed"); } } Part of uniq -c on file with output: 102 Element removed 102 Element added 102 Element removed 102 Element added 102 Element removed 102 Element added 102 Element removed 102 Element added 102 Element removed 102 Element added 102 Element removed 102 Element added 2 Element removed 2 Element added 102 Element removed 102 Element added

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• Basic QT Event handling / Threading questions ?

  - by umanga

  Greetings , I am new to QT (4.6) and have some basic questions regarding its event mechanism.I come from Swing background so I am trying to compare it with QT. 1) Does Event-processing-loop run in seperate thread? (like EventDispatch thread in Swing) ? 2) If we open several 'QMainWindow' do they run in several threads? 3) Whats the best way to run an intensive process in a seperate thread? (like SwingWorker in Swing ? ) 4) If intesive-process runs in a seperate thread ,is it possible to call UI methods like update(),repaint() from that process? thanks in advance.

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• Losing scope for DataContex using LINQToSQL intermediately

  - by greektreat

  I am having a weird Situation with my DataConext. All My code is in C# I have a DLL project for my data access layer and business Layer which and Winforms project for my UI layer. My Data access Layer's Namespace is xxx.Data this is where have my xxx.dbml I also have xxx.Data.BusinessObjects name space of course for my business object in that project In my UI Layer I have these namespaces xxxApp(for Forms), xxxApp.Controls (For Controls) I have lost scope of the DataContext, it was accessible now when I do a Rebuild Solution I sometimes get compile errors saying for example: Error 34 'xxx.Data.xxxDataContext' does not contain a definition for 'SubmitChanges' and no extension method 'SubmitChanges' accepting a first argument of type 'xxx.Data.xxxDataContext' could be found (are you missing a using directive or an assembly reference?) Also intelisense doesn't recognize the methods and table classes from my xxxDataContext anymore I can access all object fine when I am in the DLL project but now in the Winforms project this is very strange. If anyone can help me out I would be extremely grateful!

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• Giving proper credit to a projects contributors

  - by Greg B

  I've recently been working with an opensource library for a commercial product. The opensource code is distributed from the website of the company who sells the proprietary product as a zip file. The library is a (direct) port to C# of the original library which is in Java. As such, it uses methods instead of getter/setter properties. The code contains copyright notices to the supplier of the product. The C# port was originally provided to the company by a 3rd party individual. I have modified the source to be more C# like and added a couple of small features. I want to put my version of the code out there (Google code or where ever) so that C# users of the software can benefit from a more native feeling library. How can I and/or how should I amend the copyright notice to give proper credit to The comercial owner of the original source The guy who provided the original C# port Myself and anyone else who contributes to the project in the future The source is provided under the LGPL V2.1,

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• How can I add an event handler to an event by name?

  - by cyclotis04

  I'm attempting to add an event handler for every control on my form. The form is a simple info box which pops up, and clicking anywhere on it does the same thing (sort of like Outlook's email notifier.) To do this, I've written a recursive method to add a MouseClick handler to each control, as follows: private void AddMouseClickHandler(Control control, MouseEventHandler handler) { control.MouseClick += handler; foreach (Control subControl in control.Controls) AddMouseClickHandler(subControl, handler); } However, if I wanted to add a handler for all of the MouseDown and MouseUp events, I'd have to write two more methods. I'm sure there's a way around this, but I can't find it. I want a method like: private void AddRecursiveHandler(Control control, Event event, EventHandler handler) { control.event += handler; foreach (Control subControl in control.Controls) AddRecursiveHandler(subControl, event, handler); }

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