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  • what is serialization and how it works

    - by Rozer
    I know the serialization process but have't implemented it. In my application i have seen there are various classes that has been implemented serilizable interface. consider following class public class DBAccessRequest implements Serializable { private ActiveRequest request = null; private Connection connection = null; private static Log log = LogFactory.getLog(DBAccessRequest.class); public DBAccessRequest(ActiveRequest request,Connection connection) { this.request = request; this.connection = connection; } /** * @return Returns the DB Connection object. */ public Connection getConnection() { return connection; } /** * @return Returns the active request object for the db connection. */ public ActiveRequest getRequest() { return request; } } just setting request and connection in constructor and having getter setter for them. so what is the use of serilizable implementation over here...

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  • Dealloc'd Predicate crashing iPhone App!

    - by DVG
    To preface, this is a follow up to an inquiry made a few days ago: http://stackoverflow.com/questions/2981803/iphone-app-crashes-when-merging-managed-object-contexts Short Version: EXC_BAD_ACCESS is crashing my app, and zombie-mode revealed the culprit to be my predicate embedded within the fetch request embedded in my Fetched Results Controller. How does an object within an object get released without an explicit command to do so? Long Version: Application Structure Platforms View Controller - Games View Controller (Predicated upon platform selection) - Add Game View Controller When a row gets clicked on the Platforms view, it sets an instance variable in Games View for that platform, then the Games Fetched Results Controller builds a fetch request in the normal way: - (NSFetchedResultsController *)fetchedResultsController{ if (fetchedResultsController != nil) { return fetchedResultsController; } //build the fetch request for Games NSFetchRequest *request = [[NSFetchRequest alloc] init]; NSEntityDescription *entity = [NSEntityDescription entityForName:@"Game" inManagedObjectContext:context]; [request setEntity:entity]; //predicate NSPredicate *predicate = [NSPredicate predicateWithFormat:@"platform == %@", selectedPlatform]; [request setPredicate:predicate]; //sort based on name NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES]; NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil]; [request setSortDescriptors:sortDescriptors]; //fetch and build fetched results controller NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:request managedObjectContext:context sectionNameKeyPath:nil cacheName:@"Root"]; aFetchedResultsController.delegate = self; self.fetchedResultsController = aFetchedResultsController; [sortDescriptor release]; [sortDescriptors release]; [predicate release]; [request release]; [aFetchedResultsController release]; return fetchedResultsController; } At the end of this method, the fetchedResultsController's _fetch_request - _predicate member is set to an NSComparisonPredicate object. All is well in the world. By the time - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section gets called, the _predicate is now a Zombie, which will eventually crash the application when the table attempts to update itself. I'm more or less flummoxed. I'm not releasing the fetched results controller or any of it's parts, and the only part getting dealloc'd is the predicate. Any ideas?

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  • When (and why) is {} undefined in a JavaScript console?

    - by JS_Riddler
    In the console of both FF and Chrome, {} is considered undefined until explicitly evaluated: {}; // undefined ({}); // ? Object Actually, it's a bit less defined than undefined -- it's apparently bad syntax: {} === undefined; // SyntaxError: Unexpected token === {}.constructor; // SyntaxError: Unexpected token . But not if it's on the other side, in which case it's fine: "[object Object]" == {}.toString(); // true Or if it's not the first expression: undefined + undefined; // NaN {} + undefined; // NaN undefined + {}; // "undefined[object Object]" What gives?

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  • Understanding c++ block of code

    - by kotoko
    I was given a c++ main and have to code it so it works. I am having some trouble understanding the code as I am a bit new to cpp. Here is the code int main(int argc, char *argv[]) { Class::setAtribute("string"); Class(Class::CONSTANT) << "starting up..."; } Some questions: How can the first line work with no variables? Is it static? The second line is really strange for me, what I can make out is a Constructor that takes in a class constante and then prints it out somehow? If someone could explain me this bit of code it would be great! Thanks in advance.

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  • How do I create static instances of a class inside that class?

    - by wehas
    I have a class Color that holds values for the red, green, and blue channels of a color. The class constructor lets you create a new color by specifying values for the three channels. However, for convenience, I would also like to have some "premade" colors available for the programmer. For example instead of having something like DrawRectangle(new Color(1, 0, 0)); you would be able to say DrawRectangle(Color.Red); Where Color.Red is an instance of Color that lives inside the Color class. How can I declare these instances of Color inside the Color class? If there is a name for this type of technique I'd like to know it as I had no idea what search terms to use when I was looking for help online.

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  • OBject access from different functions in VC++

    - by sijith
    Hi, I have 3 function in my class B. These three function have to access member function of other class A. I did this by creating object of class A in class B constructor and tried to access that object in functions of class B. But its showing error. How can i assess the same object in these three functions. Where i have to create object of class A B::B() { A a; } B:: function() { a.fun(); //fun belongs to class A } B:: function1() { a.fun1(); //fun1 belongs to class A } I am getting error, How can i implement the same where i can access object a in both function.

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  • Why does my perl script return a zero return code when I explicitly call exit with a non-zero parame

    - by Tom Duckering
    I have a perl script which calls another script. The perl script should be propagating the script's return code but seems to be returning zero to its caller (a Java application) desipte the explicit call to exit $scriptReturnCode. It's probably something dumb since I'm by no means a perl expert. Code and output as follows (I realise that <=> could/should be != but that's what I have): print "INFO: Calling ${scriptDirectory}/${script} ${args}" $scriptReturnCode = system("${scriptDirectory}/${script} ${args}"); if ( $scriptReturnCode <=> 0 ) { print "ERROR: The script returned $scriptReturnCode\n"; exit $scriptReturnCode; } else { print "INFO: The script returned $scriptReturnCode.\n"; exit 0; } The output I have from my Java is: 20/04/2010 14:40:01 - INFO: Calling /path/to/script/script.ksh arg1 arg2 20/04/2010 14:40:01 - Could not find installer files <= this is from the script.ksh 20/04/2010 14:40:01 - ERROR: The script returned 256 20/04/2010 14:40:01 - Command Finished. Exit Code: 0 <= this is the Java app.

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  • How do I delete duplicates between two excel sheets quickly vba

    - by MainTank
    I am using vba and I have two sheets one is named "Do Not Call" and has about 800,000 rows of data in column A. I want to use this data to check column I in the second sheet, named "Sheet1". If it finds a match I want it to delete the whole row in "Sheet1". I have tailored the code I have found from a similar question here: Excel formula to Cross reference 2 sheets, remove duplicates from one sheet and ran it but nothing happens. I am not getting any errors but it is not functioning. Here is the code I am currently trying and have no idea why it is not working Option Explicit Sub CleanDupes() Dim wsA As Worksheet Dim wsB As Worksheet Dim keyColA As String Dim keyColB As String Dim rngA As Range Dim rngB As Range Dim intRowCounterA As Integer Dim intRowCounterB As Integer Dim strValueA As String keyColA = "A" keyColB = "I" intRowCounterA = 1 intRowCounterB = 1 Set wsA = Worksheets("Do Not Call") Set wsB = Worksheets("Sheet1") Dim dict As Object Set dict = CreateObject("Scripting.Dictionary") Do While Not IsEmpty(wsA.Range(keyColA & intRowCounterA).Value) Set rngA = wsA.Range(keyColA & intRowCounterA) strValueA = rngA.Value If Not dict.Exists(strValueA) Then dict.Add strValueA, 1 End If intRowCounterA = intRowCounterA + 1 Loop intRowCounterB = 1 Do While Not IsEmpty(wsB.Range(keyColB & intRowCounterB).Value) Set rngB = wsB.Range(keyColB & intRowCounterB) If dict.Exists(rngB.Value) Then wsB.Rows(intRowCounterB).delete intRowCounterB = intRowCounterB - 1 End If intRowCounterB = intRowCounterB + 1 Loop End Sub I apologize if the above code is not in a code tag. This is my first time posting code online and I have no idea if I did it correctly.

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  • PHP inheriting/extending a particular instance of an Object

    - by delta9
    Is there any way to force PHP to extend an existing/particular (and for that matter, already instantiated) instance of an object? This imaginary code should explain what I am wondering: class Base { public $var; function __construct($var){ $this->var = $name; } } class Extender extends Base { function __construct($parent) { parent = $parent; } } $base = new Base('yay!'); $extender = new Extender($base); echo 'Extended base var value: '.$extender->var.'<br/>'; Output (would be): Extended base var value: yay! To be clear, I am wanting to instantiate an object that extends a PARTICULAR INSTANCE of another object, one that has already been instantiated. I am aware that I can pass a reference to an object to another object (via it's constructor function) and then add it as a property of the receiving object, I'm wondering if there is a real way to do this?

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  • Java - Confused by the one class per file rule

    - by Mark
    The one class per file rule in Java has me a bit confused. I writing an Android app and trying to implement the accepted answer to this question: Common class for AsyncTask in Android? which calls for an interface definition which class A implements and class B accepts as an argument to its constructor. So I need an A.java and a B.java, but where does the interface go? Does it need a separate java file itself? Do I have to define it inside both A and B? If not how to import it? Also I will have about 10 different AsyncTask classes, but I don't want to bother creating a new file for each one. What would you recommend? Is there a way to put all 10 classes in one file? Or should I create a big if/then block inside the class and pass an argument telling it which of the 10 different tasks I want it to do?

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  • MVC Pages that require the user to be logged in

    - by keithjgrant
    I'm working on a little MVC framework and I'm wondering what the "best way" is to structure things so secure pages/controllers always ensure the user is logged in (and thus automatically redirects to a login page--or elsewhere--if not). Obviously, there are a lot of ways to do it, but I'm wondering what solution(s) are the most common or are considered the best practice. Some ideas I had: Explicitly call user->isLoggedIn() at the beginning of your controller action method? (Seems far too easy to forget and leave an important page unsecure on accident) Make your controller extend a secureController that always checks for login in the constructor? Do this check in the model when secure information is requested? (Seems like redundant calls would be made) Something else entirely? Note: I'm working in PHP, though the question is not language-dependent.

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  • Unity 2.0. How to throw ResolutionFailedException

    - by Andrey Khataev
    Hello, I have my app, using functionality that is based on unity application block. Sometimes I need to throw ResolutionFailedException manually. In v1.2 constructor of ResolutionFailedException had three parameters - typerequested, namerequested and exception. In v2.0 fourth parameter was added - buildercontext. I'm not creating it manually, so I have no reference to it and no idea where I can get it. Roughly speaking, I'm only overriding Resolve method in particular way and I'm not interfere in standard mechanism of policies, strategies and so on. Could anyone help?

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  • Allowing Xform controls for optional XML elements

    - by Cam
    Hi, In designing an XForm interface to an XML database (using eXist and XSLTForms), I'd like to include an input control for an optional element. The XML data records already exist and while some contain the optional element, others don't. To update a record, I'm using the existing XML record as the model instance. The problem is that the form control is not displayed when the optional element is not present, which is logical, but presents a problem when a user wants to add data to the optional element. To be more explicit, here's an example data record, data.xml: <a> <b>content</b> </a> with RNC schema: start = element a { element b { text }, element notes { text }? } XForms model: <xf:model> <xf:instance xmlns="" src="data.xml"/> <xf:submission id="save" method="post" action="update.xq" /> </xf:model> And control: <xf:input ref="/a/notes"> <xf:label>Notes (optional): </xf:label> </xf:input> The problem is that the 'Notes' input control is simply not displayed. An obvious solution is to add a trigger button to allow the user to insert the element if needed, but it is preferable to just have the input control appear, and be empty. My question is: is there some subtle combination of lesser-know attributes/binds/multiple instances/xpath expressions that will cause the control to always be displayed? Thanks

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  • C++: use array of strings wrapped in namespace?

    - by John D.
    I got the following code, wishing to wrap a group of strings nicely in a namespace: namespace msgs { const int arr_sz = 3; const char *msg[arr_sz] = {"blank", "blank", "blank" }; msg[0] = "Welcome, lets start by getting a little info from you!\n"; msg[1] = "Alright, bla bla bla.."; msg[2] = "etc."; } The code inside works nicely inside a function, but I don't know how to return an array from it. The namespace idea LOOKS fine, but it returns on the last three lines: error: expected constructor, destructor, or type conversion before ‘=’ token Why can't I define the array inside a namespace, do I need to do something first? It's nice because I can call it like printf(msgs::msg[1]) etc. I want to do this I just can't wrap my head around what's wrong :(

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  • Why would a 'public event EventHandler cccc' be null?

    - by Matt
    Why would a 'public event EventHandler cccc' be null? I have a class that's public class Builder { public event EventHandler StartedWorking; public Builder() { // Constructor does some stuff } public void Start() { StartedWorking(this, eventargobject); //StartedWorking is null -- } } This seems straightforward and something I do all the time? Am I missing something obvious or is there something that could cause this? EDIT: Does this mean that if I fire an event that is not subscribed to in a client class I have to check that it is not null? EDIT-2: I guess I'd never had events that were never not subscribed to and hence never ran into this -- You learn something new every day Sorry about the seemingly stupid question....

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  • Empty Datagrid problem in VB6

    - by Hybrid SyntaX
    Hello Recently, i encountered a problem; when I bind a recordset to datagrid ,and run the application the datagrid is not populated even though recordset has data I use the following code Option Explicit Dim conn As New ADODB.Connection Dim cmd As New ADODB.Command Dim recordset As New ADODB.recordset Private Sub InitializeConnection() Dim str As String str = _ "Provider=Microsoft.Jet.OLEDB.4.0;" & _ "Data Source=" + App.Path + "\phonebook.mdb;" & _ "Persist Security Info=False" conn.CursorLocation = adUseClient conn.ConnectionString = str conn.Open (conn.ConnectionString) End Sub Private Sub AbandonConnection() If conn.State <> 0 Then conn.Close End If End Sub Private Sub Persons_Read() Dim qry_all As String ' qry_all = "select * from person,web,phone Where web.personid = person.id And phone.personid = person.id" qry_all = "SELECT * FROM person" Call InitializeConnection cmd.CommandText = qry_all cmd.CommandType = adCmdText Set cmd.ActiveConnection = conn If conn.State = 1 Then Set recordset = cmd.Execute() End If Call BindDatagrid Call AbandonConnection End Sub Private Function Person_Add() End Function Private Function Person_Delete() End Function Private Function Person_Update() End Function Private Sub BindDatagrid() Set dg_Persons.DataSource = recordset dg_Persons.Refresh End Sub Private Sub cmd_Add_Click() Person_Add End Sub Private Sub cmd_Delete_Click() Person_Delete End Sub Private Sub cmd_Update_Click() Person_Update End Sub Private Sub Form_Load() Call Persons_Read End Sub Private Sub mnu_About_Click() frm_About.Show End Sub Thanks in advance

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  • Qt "no matching function for call"

    - by Blin
    I have no matching function for call to 'saveLine::saveLine()' error when compiling my application. The construcor is never actually called. saveLine class definition: class saveLine { public: saveLine(QWidget *parent); private: QPushButton *selectButton, *acceptButton; QLabel *filePath; QLineEdit *allias; }; saveLine is used in another class which is defined as follows: class MWindow : public QWidget { Q_OBJECT public: MWindow(QWidget *parent=0); private: saveLine line1; }; error points to MWindow constructor implementation MWindow::MWindow(QWidget *parent):QWidget(parent) { this->setWindowTitle("Launcher"); this->resize(600,600); } What should i do? I intend to use saveLine class in a vector, to create lines at runtime.

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  • How to order my objects in a C++ class correctly

    - by Julen
    Hello, I have been coding regurlarly in C++ in the past months. I am getting used to it step by step... but there are things that confuse me about formatting. I know there is a lot of legacy from C that I supousee mixes with C++. This time I have doubts about how to order properly my members and functions within in a class. Also considering their access modifiers. How is the convention in this? Until know I am doing everything "public" and writing first constructor of class, then destructor, next members and finally functions. It this correct? What happens when introducing "private" and "protected" access modifiers or "virtual" functions? From the documents I have look in the Internet there is different ways of doing things. But my questions aims to get the knowledge from a community that develops in C++ that I want to blend into. ;-) Thanks a lot!!!

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  • Java - Does null variable require space in memory

    - by Yatendra Goel
    class CheckStore { private String displayText; private boolean state; private String meaningfulText; private URL url; public CheckStore(String text, boolean state) { this.displayText = text; this.state = state; } : : } As I am initializing only two variables (displayText and state) in the constructor, Will the rest two variables (meaningfulText and url which will have the value null) will require space in memory to store null value. Q1. I think they will require space. If they will, then how much memory does a null value takes in the memory (like int takes 4 bytes). Q2. How much space a string takes in memory. I guess it will depend on the length of the string. So how much space a string takes of how much length?

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  • Change a registry value in vb.net

    - by mhofer
    Hello, I have searched a lot to find a solution for my problem, but I can't find any specific solution. I need to change a value which is stored under HKEY_LOCAL_MACHINE\SOFTWARE\APP_NAME. It is not possible to use .NET's registry functions, since they have drastic restrictions. The following snippet should solve my problem: Dim regKey As RegistryKey Dim ver As Decimal regKey = My.Computer.Registry.LocalMachine.OpenSubKey("HKEY_LOCAL_MACHINE\SOFTWARE\APP_NAME", True) regKey.SetValue("IP", "192.168.10.15:18500") regKey.Close() Unfortunately, I get a NullReferenceExeption when I try to set the value. What should I do? I have imported Microsoft.Win32 and RegistryKey doesn't accept any constructor... cheers mike

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  • Using the JPA Criteria API, can you do a fetch join that results in only one join?

    - by Shaun
    Using JPA 2.0. It seems that by default (no explicit fetch), @OneToOne(fetch = FetchType.EAGER) fields are fetched in 1 + N queries, where N is the number of results containing an Entity that defines the relationship to a distinct related entity. Using the Criteria API, I might try to avoid that as follows: CriteriaBuilder builder = entityManager.getCriteriaBuilder(); CriteriaQuery<MyEntity> query = builder.createQuery(MyEntity.class); Root<MyEntity> root = query.from(MyEntity.class); Join<MyEntity, RelatedEntity> join = root.join("relatedEntity"); root.fetch("relatedEntity"); query.select(root).where(builder.equals(join.get("id"), 3)); The above should ideally be equivalent to the following: SELECT m FROM MyEntity m JOIN FETCH myEntity.relatedEntity r WHERE r.id = 3 However, the criteria query results in the root table needlessly being joined to the related entity table twice; once for the fetch, and once for the where predicate. The resulting SQL looks something like this: SELECT myentity.id, myentity.attribute, relatedentity2.id, relatedentity2.attribute FROM my_entity myentity INNER JOIN related_entity relatedentity1 ON myentity.related_id = relatedentity1.id INNER JOIN related_entity relatedentity2 ON myentity.related_id = relatedentity2.id WHERE relatedentity1.id = 3 Alas, if I only do the fetch, then I don't have an expression to use in the where clause. Am I missing something, or is this a limitation of the Criteria API? If it's the latter, is this being remedied in JPA 2.1 or are there any vendor-specific enhancements? Otherwise, it seems better to just give up compile-time type checking (I realize my example doesn't use the metamodel) and use dynamic JPQL TypedQueries.

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  • Why is there "data" and "newtype" in Haskell?

    - by martingw
    To me it seems that a newtype definition is just a data definition that obeys some restrictions (only one constructor and such), and that due to these restrictions the runtime system can handle newtypes more efficiently. Ok, and the handling of pattern matching for undefined values is slightly different. But suppose Haskell would only knew data definitions, no newtypes: Couldn't the compiler find out for himself whether a given data definition obeys these restrictions, and automatically treat it more efficiently? I'm sure I'm missing out on something, these Haskell designers are so clever, there must be some deeper reason for this...

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  • C# ToolTip will not re-appear after first use.

    - by Roberto Sebestyen
    I have a Forms C# application where I would like to use a toolTip on one of the text boxes. I Initialize the tool-tip in the constructor of the Form class, and it works the first time. So when I hover over the text box with my mouse it works, but once the toolTip times out and it goes away, it does not re-appear when I move my mouse away and back onto the control. I would expect it to come back and I'm wondering what I'm doing wrong. Here is how I initialize the tooltip: myTip = new ToolTip(); myTip.ToolTipIcon = ToolTipIcon.Info; myTip.IsBalloon = true; myTip.ShowAlways = true; myTip.SetToolTip(txtMyTextBox,"My Tooltip Text");

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  • Sorting and displaying a custom QVariant type.

    - by Kranar
    Hello, I have a custom type I'd like to use with QVariant but I don't know how to get the QVariant to display in a table or have it sort in a QSortFilterProxyModel. I register the type with Q_DECLARE_METATYPE and wrote streaming operators registered via qRegisterMetaTypeStreamOperators but for whatever reason when I use the type with a table model, it doesn't display anything and it doesn't sort. I should specify that this custom type can not be modified. It has a copy and default constructor, but I can not go in and modify the source code to get it to work with QVariant. Is there a way of non-intrusively getting the behaviour I'd like?

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  • WPF Prism deactivate ?

    - by 2Fast4YouBR
    Hi all, I have an problem and would like to know if it is common problem or jsut with me. I am using Wpf with Prism and Unity, all with the pattern MvvM. I am loading a viewModel that has a reference to a dropdown with few items, my idea is that each time that the user click in some place to open the view that has this dropdown is that the dropdown will be shown with diferent values. The problem is that I see is that after I show the view for the first time and after the first DEACTIVATE, when I try to load it again looks like it is already in the memory (was not deactivated/disposed), so as is already in memory, it not call the constructor again of the modelView and the dropdown is shown with tha same old values. public BranchSelectionViewModel(IUnityContainer unityContainer) { this.unityContainer = unityContainer; User user = this.unityContainer.Resolve<User>(); this.branches = new ObservableCollection<Department>(user.Departments .Where(department => department.DepartmentId != user.SelectedDepartment.DepartmentId)); }

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