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  • Boost.Python wrapping hierarchies avoiding diamond inheritance

    - by stbuton
    I'm having some trouble seeing what the best way to wrap a series of classes with Boost.Python while avoiding messy inheritance problems. Say I have the classes A, B, and C with the following structure: struct A { virtual void foo(); virtual void bar(); virtual void baz(); }; struct B : public A { virtual void quux(); }; struct C : public A { virtual void foobar(); }; I want to wrap all classes A, B, and C such that they are extendable from Python. The normal method for accomplishing this would be along the lines of: struct A_Wrapper : public A, boost::python::wrapper<A> { //dispatch logic for virtual functions }; Now for classes B and C which extend from A I would like to be able to inherit and share the wrapping implementation for A. So I'd like to be able to do something along the lines of: struct B_Wrapper : public B, public A_Wrapper, public boost::python::wrapper<B> { //dispatch logic specific for B }; struct C_Wrapper : public C, public A_Wrapper, public boost::python::wrapper<C> { //dispatch logic specific for C } However, it seems like that would introduce all manner of nastiness with the double inheritance of the boost wrapper base and the double inheritance of A in the B_Wrapper and C_Wrapper objects. Is there a common way that this instance is solved that I'm missing? thanks.

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  • JVM/CLR Source-compatible Language Options

    - by Nathan Voxland
    I have an open source Java database migration tool (http://www.liquibase.org) which I am considering porting to .Net. The majority of the tool (at least from a complexity side) is around logic like "if you are adding a primary key and the database is Oracle use this SQL. If database is MySQL use this SQL. If the primary key is named and the database is Postgres use this SQL". I could fork the Java codebase and covert it (manually and/or automatically), but as updates and bug fixes to the above logic come in I do not want to have to apply it to both versions. What I would like to do is move all that logic into a form that can be compiled and used by both Java and .Net versions naively. The code I am looking to convert does not contain any advanced library usage (JDBC, System.out, etc) that would vary significantly from Java to .Net, so I don't think that will be an issue (at worst it can be designed around). So what I am looking for is: A language in which I can code common parts of my app in and compile it into classes usable by the "standard" languages on the target platform Does not add any runtime requirements to the system Nothing so strange that it scares away potential contributors I know Python and Ruby both have implementations on for the JVM and CLR. How well do they fit my requirements? Has anyone been successful (or unsuccesful) using this technique for cross-platform applications? Are there any gotcha's I need to worry about?

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  • How to refactor use of the general Exception?

    - by Colin
    Our code catches the general exception everywhere. Usually it writes the error to a log table in the database and shows a MessageBox to the user to say that the operation requested failed. If there is database interaction, the transaction is rolled back. I have introduced a business logic layer and a data access layer to unravel some of the logic. In the data access layer, I have chosen not to catch anything and I also throw ArgumentNullExceptions and ArgumentOutOfRangeExceptions so that the message passed up the stack does not come straight from the database. In the business logic layer I put a try catch. In the catch I rollback the transaction, do the logging and rethrow. In the presentation layer there is another try catch that displays a MessageBox. I am now thinking about catching a DataException and an ArgumentException instead of an Exception where I know the code only accesses a database. Where the code accesses a web service, then I thought I would create my own "WebServiceException", which would be created in the data access layer whenever an HttpException, WebException or SoapException is thrown. So now, generally I will be catching 2 or 3 exceptions where currently I catch just the general Exception, and I think that seems OK to me. Does anyone wrap exceptions up again to carry the message up to the presentation layer? I think I should probably add a try catch to Main() that catches Exception, attempts to log it, displays an "Application has encountered an error" message and exits the application. So, my question is, does anyone see any holes in my plan? Are there any obvious exceptions that I should be catching or do these ones pretty much cover it (other than file access - I think there is only 1 place where we read-write to a config file).

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  • Why use SQL database?

    - by martinthenext
    I'm not quite sure stackoverflow is a place for such a general question, but let's give it a try. Being exposed to the need of storing application data somewhere, I've always used MySQL or sqlite, just because it's always done like that. As it seems like the whole world is using these databases, most of all software products, frameworks, etc. It is rather hard for a beginning developer like me to ask a question - why? Ok, say we have some object-oriented logic in our application, and objects are related to each other somehow. We need to map this logic to the storage logic, so we need relations between database objects too. This leads us to using relational database and I'm ok with that - to put it simple, our database rows sometimes will need to have references to other tables' rows. But why do use SQL language for interaction with such a database? SQL query is a text message. I can understand this is cool for actually understanding what it does, but isn't it silly to use text table and column names for a part of application that no one ever seen after deploynment? If you had to write a data storage from scratch, you would have never used this kind of solution. Personally, I would have used some 'compiled db query' bytecode, that would be assembled once inside a client application and passed to the database. And it surely would name tables and colons by id numbers, not ascii-strings. In the case of changes in table structure those byte queries could be recompiled according to new db schema, stored in XML or something like that. What are the problems of my idea? Is there any reason for me not to write it myself and to use SQL database instead?

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  • What kinds of problems are most likely to occur? (question rewritten)

    - by ChrisC
    If I wrote 1) a C# SQL db app (a simple program consisting of a gui over some forms with logic for interfacing with the sql db) 2) for home use, that doesn't do any network communication 3) that uses a simple, reliable, and appropriate sql db 4) whose gui is properly separated from the logic 5) that has complete and dependable input data validation 6) that has been completely tested so that 100% of logic bugs were eliminated ... and then if the program was installed and run by random users on their random Windows computers Q1) What types of technical (non-procedural) problems and support situations are most likely to occur, and how likely are they? Q2) Are there more/other things I could do in the first place to prevent those problems and also minimize the amount of user support required? I know some answers will apply to my specific platforms (C#, SQL, Windows, etc) and some won't. Please be as specific as is possible. Mitch Wheat gave me some very valuable advice below, but I'm now offering the bounty because I am hoping to get a better picture of the kinds of things that I'm most reasonably likely to encounter. Thanks.

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  • Rhino Mocks Partial Mock

    - by dotnet crazy kid
    I am trying to test the logic from some existing classes. It is not possible to re-factor the classes at present as they are very complex and in production. What I want to do is create a mock object and test a method that internally calls another method that is very hard to mock. So I want to just set a behaviour for the secondary method call. But when I setup the behaviour for the method, the code of the method is invoked and fails. Am I missing something or is this just not possible to test without re-factoring the class? I have tried all the different mock types (Strick,Stub,Dynamic,Partial ect.) but they all end up calling the method when I try to set up the behaviour. using System; using MbUnit.Framework; using Rhino.Mocks; namespace MMBusinessObjects.Tests { [TestFixture] public class PartialMockExampleFixture { [Test] public void Simple_Partial_Mock_Test() { const string param = "anything"; //setup mocks MockRepository mocks = new MockRepository(); var mockTestClass = mocks.StrictMock<TestClass>(); //record beahviour *** actualy call into the real method stub *** Expect.Call(mockTestClass.MethodToMock(param)).Return(true); //never get to here mocks.ReplayAll(); //this is what i want to test Assert.IsTrue(mockTestClass.MethodIWantToTest(param)); } public class TestClass { public bool MethodToMock(string param) { //some logic that is very hard to mock throw new NotImplementedException(); } public bool MethodIWantToTest(string param) { //this method calls the if( MethodToMock(param) ) { //some logic i want to test } return true; } } } }

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  • Loop a formula in excel VBA

    - by CEMG
    I am trying to loop a formula in Column "D" until Column "B" doesn't have any more data. The formula I am adding to Column "D" is : IF(ISNUMBER(C5),C5,IF(C5A5/3+OFFSET(C5,-1,0)) ,IF(C5<C6,((OFFSET(C5,1,0)-OFFSET(C5,-2,0))(A5/3)+OFFSET(C5,-2,0)),""))) So the result I want in Column "D" once the macro is run is this: A B C D 3 May-10 78.0000 78.00000 1 Jun-10 52.06667 2 Jul-10 26.13333 3 Aug-10 0.2000 0.20000 1 Sep-10 0.21393 2 Oct-10 0.22786 3 Nov-10 0.2418 0.24179 1 Dec-10 0.26640 2 Jan-11 0.29102 3 Feb-11 0.3156 0.31563 1 Mar-11 0.34821 2 Apr-11 0.38080 3 May-11 0.4134 0.41338 1 Jun-11 0.44992 2 Jul-11 0.48646 3 Aug-11 0.5230 0.52300 1 Sep-11 0.56440 2 Oct-11 0.60580 3 Nov-11 0.6472 0.64720 1 Dec-11 0.43147 If someone can help me at what I am doing wrong with the VBA codes I would greatly appreciated. My CODES are the following: Sub IsNumeric() // first logic: IF(ISNUMBER(C6),C6 // If Application.IsNumber(Range("c5").Value) Then Range("d5").Value = Range("C5").Value // second logic: IF(C6 ElseIf Range("c6").Value < Range("c5").Value Then Range("d6").Value = Range("c6").Offset(2, 0).Value - Range("c6").Offset(-1, 0).Value * (Range("a6").Value / 3) + Range("c6").Offset(-1, 0).Value // third logic: IF(C6<C7,((OFFSET(C6,1,0)-OFFSET(C6,-2,0))*(A6/3)+OFFSET(C6,-2,0)),""))) // ElseIf Range("c6").Value < Range("c7").Value Then Range("d6").Value = (Range("c6").Offset(1, 0).Select) - Range("c6").Offset(-2, 0).Select * (Range("a6").Select / 3) + Range("c6").Offset(-2, 0).Select Else Range("d6").Value = "" End If End Sub

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  • Calling a subclass method from a superclass

    - by Shaun
    Preface: This is in the context of a Rails application. The question, however, is specific to Ruby. Let's say I have a Media object. class Media < ActiveRecord::Base end I've extended it in a few subclasses: class Image < Media def show # logic end end class Video < Media def show # logic end end From within the Media class, I want to call the implementation of show from the proper subclass. So, from Media, if self is a Video, then it would call Video's show method. If self is instead an Image, it would call Image's show method. Coming from a Java background, the first thing that popped into my head was 'create an abstract method in the superclass'. However, I've read in several places (including Stack Overflow) that abstract methods aren't the best way to deal with this in Ruby. With that in mind, I started researching typecasting and discovered that this is also a relic of Java thinking that I need to banish from my mind when dealing with Ruby. Defeated, I started coding something that looked like this: def superclass_method # logic this_media = self.type.constantize.find(self.id) this_media.show end I've been coding in Ruby/Rails for a while now, but since this was my first time trying out this behavior and existing resources didn't answer my question directly, I wanted to get feedback from more-seasoned developers on how to accomplish my task. So, how can I call a subclass's implementation of a method from the superclass in Rails? Is there a better way than what I ended up (almost) implementing?

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  • Handling user interface in a multi-threaded application (or being forced to have a UI-only main thre

    - by Patrick
    In my application, I have a 'logging' window, which shows all the logging, warnings, errors of the application. Last year my application was still single-threaded so this worked [quite] good. Now I am introducing multithreading. I quickly noticed that it's not a good idea to update the logging window from different threads. Reading some articles on keeping the UI in the main thread, I made a communication buffer, in which the other threads are adding their logging messages, and from which the main thread takes the messages and shows them in the logging window (this is done in the message loop). Now, in a part of my application, the memory usage increases dramatically, because the separate threads are generating lots of logging messages, and the main thread cannot empty the communication buffer quickly enough. After the while the memory decreases again (if the other threads have finished their work and the main thread gradually empties the communication buffer). I solved this problem by having a maximum size on the communication buffer, but then I run into a problem in the following situation: the main thread has to perform a complex action the main thread takes some parts of the action and let's separate threads execute this while the seperate threads are executing their logic, the main thread processes the results from the other threads and continues with its work if the other threads are finished Problem is that in this situation, if the other threads perform logging, there is no UI-message loop, and so the communication buffer is filled, but not emptied. I see two solutions in solving this problem: require the main thread to do regular polling of the communication buffer only performing user interface logic in the main thread (no other logic) I think the second solution seems the best, but this may not that easy to introduce in a big application (in my case it performs mathematical simulations). Are there any other solutions or tips? Or is one of the two proposed the best, easiest, most-pragmatic solution? Thanks, Patrick

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  • Start with remoting or with WCF

    - by Sheldon
    Hi. I'm just starting with distributed application development. I need to create (all by myself) an enterprise application for document management. That application will run on an intranet (within the firewall, no internet access is required now, BUT is probably that will be later). The application needs to manage images that will be stored within MySQL Server (as blobs) and those images will be then recovered by the app and eventually one or more of them will be converted to PDF. Performance is the most important non-functional requirement. I have a couple of doubts. What do you suggest to use, .NET Remoting or WCF over TCP-IP (I think second one is the best for the moment I need to expose the business logic over internet, changing the protocol). Where do you suggest to make the transformation of the images to pdf files, I'm using iText. (I have thought to have the business logic stored within the IIS and exposed via WCF, and that business logic to be responsible of getting the images and transforming them to PDF, that because the IIS and the MySQL Server are the same physical machine). I ask about where to do the transformation because the app must be accessible from multiple devices, and for example, for mobile devices, the pdf maybe is not necessary. Thank you very much in advance.

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  • C# app running as either Windows Form or as Console Application

    - by Aeolien
    I am looking to have one of my Windows Forms applications be run programmatically—from the command line. In preparation, I have separated the logic in its own class from the Form. Now I am stuck trying to get the application to switch back and forth based on the presence of command line arguments. Here is the code for the main class: static class Program { /// <summary> /// The main entry point for the application. /// </summary> [STAThread] static void Main() { string[] args = Environment.GetCommandLineArgs(); if (args.Length > 1) // gets passed its path, by default { CommandLineWork(args); return; } Application.EnableVisualStyles(); Application.SetCompatibleTextRenderingDefault(false); Application.Run(new Form1()); } private static void CommandLineWork(string[] args) { Console.WriteLine("It works!"); Console.ReadLine(); } where Form1 is my form and the It works! string is just a placeholder for the actual logic. Right now, when running this from within Visual Studio (with command line arguments), the phrase It works! is printed to the Output. However, when running the /bin/Debug/Program.exe file (or /Release for that matter) the application crashes. Am I going about this the right way? Would it make more sense (i.e. take less developer time) to have my logic class be a DLL that gets loaded by two separate applications? Or is there something entirely different that I'm not aware of? Thanks in advance!

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  • How do I convert a simple ruby flashcard program into a ROR app?

    - by Mark Wilbur
    What I'm trying to do is make a basic flashcard app on rails. At this point, all I'm looking for is the functionality to iterate through a list of flashcards, quiz the user and let the user know if they were right or not. In ruby, it didn't take me long to write: class Card attr_accessor :answer, :question def initialize(answer = "", question="") @answer = answer @question = question end def quiz puts "What does #@question mean?" answer = gets.chomp if answer == @answer puts "Right" return true else puts "Wrong" return answer end end end class Cardlist attr_accessor :Cards def initialize(Cards = []) @Cards = Cards end def quiz Cards.each do |w| w.quiz end end end The problem I'm having with rails is figuring out where to put the logic to loop through all the cards in the list. I've made models specifying that Card belongs_to cardlist and that Cardlist has_many cards. I know application logic should go in the controller, but if I were to make a "quiz" action for my Cardlist controller, how would I make it iterate through all the cards? After each "quiz" page generated, I'd need to get an answer back from the user, respond (maybe flash) whether it was right or not and then continue onto the next question. Would any of that logic have to go into the view in order to make sure it's sending back the user inputted answers to the controller?

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  • Signed_request lost in ASP.NET session, confusing my website

    - by Csabi
    I have an ASP.NET MVC 3 website which is available both from a specific public url, and I'm also making be available as a Facebook App. Inside my website logic, in some places I have to determine whether the current request is from the Facebook-app, or from the public website, because I want to display content based on this environment. So, for eg. if the user is using my site as a facebook-app, then I want to display a picture, and if the user is using my site normally, then I don't wanna display a picture. To determine whether I'm from a Facebook app, I check the "signed_request" in the HttpContext.Request, and store it in the HttpSession to be available for my other actions, not just for that action (url) which is defined for my Facebook app. So when a child-action is executed, I can determine based on the Session, that the website is used as a FB-app or not. The problem happens, when the Session times out, because then althought the logic is still running inside Facebook, my logic thinks it's not inside Facebook. Any advice?

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  • PyQt - How to connect multiple signals to the same widget

    - by Orchainu
    [ ]All1 [ ]All2 [ ]checkbox1A [ ]checkbox1B [ ]checkbox2A [ ]checkbox2B Based on the chart above, a few things need to happen: The All checkboxes only affect the on/off of the column it resides in, and checks on/off all the checkboxes in that column. All checkboxes work in pairs, so if checkbox1A is on/off, checkbox1B needs to be on/off If an All checkbox is checked on, and then the user proceeds to check off one or more checkbox in the column, the All checkbox should be unchecked, but all the checkboxes that are already checked should remain checked. So really this is more like a chain reaction setup. If checkbox All1 is on, then chieckbox1A and 2A will be on, and because they are on, checkbox1B and 2B are also on, but checkbox All2 remains off. I tried hooking up the signals based on this logic, but only the paired logic works 100%. The All checkbox logic only works 50% of the time, and not accurately, and there's no way for me to turn off the All checkbox without turning all already checked checkboxes off. Really really need help ... T-T Sample code: cbPairKeys = cbPairs.keys() for key in cbPairKeys: cbOne = cbPairs[key][0][0] cbTwo = cbPairs[key][1][0] cbOne.stateChanged.connect(self.syncCB) cbTwo.stateChanged.connect(self.syncCB) def syncCB(self): pairKeys = cbPairs.keys() for keys in pairKeys: cbOne = cbPairs[keys][0][0] cbOneAllCB = cbPairs[keys][0][4] cbTwo = cbPairs[keys][1][0] cbTwoAllCB = cbPairs[keys][1][4] if self.sender() == cbOne: if cbOne.isChecked() or cbTwoAllCB.isChecked(): cbTwo.setChecked(True) else: cbTwo.setChecked(False) else: if cbTwo.isChecked() or cbOneAllCB.isChecked(): cbOne.setChecked(True) else: cbOne.setChecked(False) EDIT Thanks to user Avaris's help and patience, I was able to reduce the code down to something much cleaner and works 100% of the time on the 1st and 2nd desired behavior: #Connect checkbox pairs cbPairKeys = cbPairs.keys() for key in cbPairKeys: cbOne = cbPairs[key][0][0] cbTwo = cbPairs[key][1][0] cbOne.toggled.connect(cbTwo.setChecked) cbTwo.toggled.connect(cbOne.setChecked) #Connect allCB and allRO signals cbsKeys = allCBList.keys() for keys in cbsKeys: for checkbox in allCBList[keys]: keys.toggled.connect(checkbox.setChecked) Only need help on turning off the All checkbox when the user selectively turns off the modular checkboxes now

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  • Can't declare an abstract method private....

    - by Zombies
    I want to do this, yet I can't. Here is my scenario and rational. I have an abstract class for test cases that has an abstract method called test(). The test() method is to be defined by the subclass; it is to be implemented with logic for a certain application, such as CRMAppTestCase extends CompanyTestCase. I don't want the test() method to be invoked directly, I want the super class to call the test() method while the sub class can call a method which calls this (and does other work too, such as setting a current date-time right before the test is executed for example). Example code: public abstract class CompanyTestCase { //I wish this would compile, but it cannot be declared private private abstract void test(); public TestCaseResult performTest() { //do some work which must be done and should be invoked whenever //this method is called (it would be improper to expect the caller // to perform initialization) TestCaseResult result = new TestCaseResult(); result.setBeginTime(new Date()); long time = System.currentTimeMillis(); test(); //invoke test logic result.setDuration(System.currentTimeMillis() - time); return result; } } Then to extend this.... public class CRMAppTestCase extends CompanyTestCase { public void test() { //test logic here } } Then to call it.... TestCaseResult result = new CRMAppTestCase().performTest();

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  • MVC design pattern in complex iPad app: is one fat controller acceptable?

    - by nutsmuggler
    I am building a complex iPad application; think of it as a scrapbook. For the purpose of this question, let's consider a page with two images over it. My main view displays my doc data rendered as a single UIImage; this because I need to do some global manipulation over them. This is my DisplayView. When editing I need to instantiate an EditorView with my two images as subviews; this way I can interact with a single image, (rotate it, scale it, move it). When editing is triggered, I hide my DisplayView and show my EditorView. In a iPhone app, I'd associate each main view (that is, a view filling the screen) to a view controller. The problem is here there is just one view controller; I've considered passing the EditorView via a modal view controller, but it's not an option (there a complex layout with a mask covering everything and palettes over it; rebuilding it in the EditorView would create duplicate code). Presently the EditorView incorporates some logic (loads data from the model, invokes some subviews for fine editing, saves data back to the model); EditorView subviews also incorporate some logic (I manipulate images and pass them back to the main EditorView). I feel this logic belongs more to a controller. On the other hand, I am not sure making my only view controller so fat a good idea. What is the best, cocoa-ish implementation of such a class structure? Feel free to ask for clarifications. Cheers.

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  • Validating a phone number in Android PreferenceScreen

    - by djechelon
    I have a PreferenceScreen in which the user is capable, if system can't autodetect it, to enter the device's phone number. I'm still learning this part of Android but I managed to understand a bit of PreferenceScreens by examples provided by Android SDK itself and a few tutorials. What I want is that the user can save the phone number only if null or valid, where by "valid" I mean running a generic validation logic (ie. an anonymous method that returns true or false, that can be reused in any possible situation*) or better, just to simplify things, ^(\+39)?3[0-9]{9}$ For now I have the following XML snip <EditTextPreference android:inputType="phone" android:key="@string/preference_phoneNo" android:selectAllOnFocus="true" android:singleLine="true" android:summary="@string/pref_phoneNumber_description" android:title="@string/pref_phoneNumber" /> and following code by courtesy of Eclipse New Activity wizard: private void setupSimplePreferencesScreen() { if (!isSimplePreferences(this)) { return; } addPreferencesFromResource(R.xml.pref_general); bindPreferenceSummaryToValue(findPreference(getString(R.string.preference_phoneNo))); } addPreferenceFromResource is supposed to load the XML node and add the preference to the screen, while binPreferenceSummaryToValue is supposed to make description text change when preference is updated. Just for sake of completeness for those who don't like code courtesy of the IDE, the second method is provided by Eclipse who also provides a private class in the code file that is /** * A preference value change listener that updates the preference's summary * to reflect its new value. */ In the general case, what should I do to perform validation logic before the preference gets saved when I click OK on the preference editor? Where is the validation logic to be put in a PreferenceScreen? *Aren't we all here to learn?

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  • What is the best way to structure those jquery call backs?

    - by user518138
    I am new to jquery and recently have been amazed how powerful those call backs are. But here I got some logic and I am not sure what the best way is. Basically, I got a bunch of tables in web sql database in chrome. I will need to go through say table A, table B and table C. I need to submit each row of the table to server. Each row represents a bunch of complicated logic and data url and they have to be submitted in the order of A - B - C. The regular java way would be: TableA.SubmitToServer() { query table A; foreach(row in tableA.rows) { int nRetID = submitToServer(row); do other updates.... } } Similar for tableB and table C. then just call: TableA.SubmitToServer(); TableB.SubmitToServer(); TableC.SubmitToServer(); //that is very clear and easy. But in JQuery, it probably will be: db.Transaction(function (tx){ var strQuery = "select * from TableA"; tx.executeSql(strQuery, [], function (tx, result){ for(i = 0 ; i < result.rows.length; i++) { submitTableARowToServer(tx, result.rows.getItem(i), function (tx, result) { //do some other related updates based on this row from tableA //also need to upload some related files to server... }); } }, function errorcallback....) }); As you can see, there are already enough nested callbacks. Now, where should I put the process for TableB and tableC? They all need to have similar logic and they can only be called after everything is done from TableA. So, What is the best way to do this in jquery? Thanks

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  • Silverlight 4 + MVVM + KeyDown event

    - by jturn
    I'm trying to build a sample game in Silverlight 4 using the MVVM design pattern to broaden my knowledge. I'm using Laurent Bugnion's MvvmLight toolkit as well (found here: http://mvvmlight.codeplex.com/ ). All I want to do right now is move a shape around within a Canvas by pressing specific keys. My solution contains a Player.xaml (just a rectangle; this will be moved around) and MainPage.xaml (the Canvas and an instance of the Player control). To my understanding, Silverlight doesn't support tunneling routed events, only bubbling. My big problem is that Player.xaml never recognizes the KeyDown event. It's always intercepted by MainPage.xaml first and it never reaches any child controls because it bubbles upward. I'd prefer that the logic to move the Player be in the PlayerViewModel class, but I don't think the Player can know about any KeyDown events firing without me explicitly passing them on down from the MainPage. I ended up adding the handler logic to the MainPageViewModel class. Now my problem is that the MainPageViewModel has no knowledge of Player.xaml so it cannot move this object when handling KeyDown events. I guess this is expected, as ViewModels should not have any knowledge of their associated Views. In not so many words...is there a way this Player user control within my MainPage.xaml can directly accept and handle KeyDown events? If not, what's the ideal method for my MainPageViewModel to communicate with its View's child controls? I'm trying to keep code out of the code-behind files as much as possible. Seems like it's best to put logic in the ViewModels for ease of testing and to decouple UI from logic. (MainPage.xaml) <UserControl x:Class="MvvmSampleGame.MainPage" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:game="clr-namespace:MvvmSampleGame" xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity" xmlns:cmd="clr-namespace:GalaSoft.MvvmLight.Command;assembly=GalaSoft.MvvmLight.Extras.SL4" mc:Ignorable="d" Height="300" Width="300" DataContext="{Binding Main, Source={StaticResource Locator}}"> <i:Interaction.Triggers> <i:EventTrigger EventName="KeyDown"> <cmd:EventToCommand Command="{Binding KeyPressCommand}" PassEventArgsToCommand="True" /> </i:EventTrigger> </i:Interaction.Triggers> <Canvas x:Name="LayoutRoot"> <game:Player x:Name="Player1"></game:Player> </Canvas> (MainViewModel.cs) public MainViewModel() { KeyPressCommand = new RelayCommand<KeyEventArgs>(KeyPressed); } public RelayCommand<KeyEventArgs> KeyPressCommand { get; private set; } private void KeyPressed(KeyEventArgs e) { if (e.Key == Key.Up || e.Key == Key.W) { // move player up } else if (e.Key == Key.Left || e.Key == Key.A) { // move player left } else if (e.Key == Key.Down || e.Key == Key.S) { // move player down } else if (e.Key == Key.Right || e.Key == Key.D) { // move player right } } Thanks in advance, Jeremy

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  • Getting FC11 to run under VMware Server, converted from physical machine

    - by Kristian
    I have a FC11 installation that I have converted to a VMware disk image to run om my VMware Server. I converted it with qemu-img, as the VMware Converter software apparently only converts Linux hosts to VMware Infrastructure servers. The disk image boots fine (grub is loaded and boots the kernel) but it seems like the disk is not found by the kernel, and the boot process stalls. Hotplugging USB devices work (the kernel prints debug information) and I'm able to press keys (Ctrl-Alt-Delete for instance). The VMware guest OS is set to RedHat Enterprise Linux 5 (32 bit), and I have tried both the LSI Logic, LSI Logic SAS and VMware Accelerated SCSI SCSI controllers, to no avail. I'm able to boot an installer disk and get into rescue mode and mount the filesystem, so my question is, what do I need to do to the guest kernel / initrd image to make it recognize the virtual disk?

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  • Who are the most important people in open-source software? [closed]

    - by poseid
    I am reading a book by Malcolm Gladwell on the circumstances of successful careers. The book argues that Bill Gates, Steve Jobs, Bill Joy and more succesful computer pioneers were born between 1950-1955, and did absolve around 10000 hours of practice before microcomputers became widely available in the 1970s and their fairy tale success story begins. As we are in the age of web 2.0 with new forms of databases and persuasive access to information, who are in your opinion the most succesful computer programmers or scientists of our times, when were they born and to which technologies they had access?

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  • What causes memory fragmentation in .NET

    - by Matt
    I am using Red Gates ANTS memory profiler to debug a memory leak. It keeps warning me that: Memory Fragmentation may be causing .NET to reserver too much free memory. or Memory Fragmentation is affecting the size of the largest object that can be allocated Because I have OCD, this problem must be resolved. What are some standard coding practices that help avoid memory fragmentation. Can you defragment it through some .NET methods? Would it even help?

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  • How are SQL Server CALs counted?

    - by Sam
    Running a SQL Server, as far as I understand it, you need one CAL for every user who connects to the database server. But what happens if the only computer which is accessing the SQL Server is the server running your business layer? If, for example, you got 1 SQL Server and 1 Business logic server, and 100 Clients who all just query and use the business logic server. No client is using the SQL Server directly, no one is even allowed to contact it. So, since there is only one computer using the SQL server, do I need only 1 CAL??? I somehow can't believe this would count as only 1 CAL needed for the SQL Server, but I would like to know why not.

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  • Does lighter wallpaper consumes lesser power than a Darker one

    - by Lamb
    My VAIO advised me to switch to a White Background, to reduce power consumption. But it seems contradictory to common logic. Its like saying a brighter Torch consuming less than a dimmer one. Common Logic says that, Screen is BLACK when not using any POWER, so displaying black color should not consume any power (because without powering any pixel it gives black color) Also a white screen gives me more light than a darker one, so it should use more Energy. White Wallpaper = More Light Output = More Electrical Energy Consumed Black Wallpaper = Less Light = Less Electricity Consumed My question is - Is there anything wrong with the above argument ? A Lighter Wallpaper consumes less power than a Darker one. Is it true ? If yes, Why ?

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  • Scripting help - need to get phone number of AD accounts and then add them to contacts in trusted domain

    - by TheCleaner
    I have domain accounts that I have created as contacts in another trusted domain so that they can see them in their Exchange GAL. I need a way to extract the phone number field from UserA (user account) in DomainA and import it into UserA (contact) in DomainB. I get the logic, it's just the code (vbscript/powershell/whatever) that eludes me. The logic as I see it: Connect to source AD (ou/subtree) Extract user accounts from OU and subcontainers including first name, last name, display name, and phone number Connect to target AD (ou/subtree) Verify/match contact with extract in #2 above based on display name Update phone field with phone number in extract Write log of success and failures Anybody able to help?

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