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  • How to instantiate a Singleton multiple times?

    - by Sebi
    I need a singleton in my code. I implemented it in Java and it works well. The reason I did it, is to ensure that in a mulitple environment, there is only one instance of this class. But now I want to test my Singleton object locally with a Unit test. For this reason I need to simulate another instance of this Singleton (the object that would be from another device). So is there a possiblity to instantiate a Singleton a second time for testing purpose or do I have to mock it? I'm not sure, but I think it could be possible by using a different class loader?

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  • In Java, how do I set a return type if an exception occurs?

    - by beagleguy
    hey all, I'm new to Java and was wondering if I define a method to return a database object like import java.sql.*; public class DbConn { public Connection getConn() { Connection conn; try { Class.forName("com.mysql.jdbc.Driver").newInstance(); if(System.getenv("MY_ENVIRONMENT") == "development") { String hostname = "localhost"; String username = "root"; String password = "root"; } conn = DriverManager.getConnection("jdbc:mysql:///mydb", username, password); return conn; } catch(Exception e) { throw new Exception(e.getMessage()); } } } if the connection fails when I try to create it what should I return? eclipse is telling me I have to return a Connection object but if it fails I'm not sure what to do. thanks!

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  • Clone a 'link' in SWT

    - by Steve
    I have a table of information that includes a username, an ip address, and a timestamp. What I wanted to do was to have the ip address contained within a link object that when the link is clicked it utilizes bgp.he.net to get information about the host/IP address. I have tried creating threads to resolve the IP addresses but it is often a large amount of IP addresses and I read that InetAddress#getByName isn't non-blocking, so I figured having links that go to this site is the next best thing. Question is: Is it possible to have links for each of my IP addresses in the table without creating a new link object for each row? I don't know how bad that would be on memory usage which is why I'm inquiring about cloning an instance of an IP and having the link open bgp.he.net/link.getText()

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  • Writing jQuery functions that allow chaining.

    - by Rich Bradshaw
    I want to write some code that allows me to replace jQuery's animate function with one that does different things, but still allows me to call a secondary function on completion. At the moment, I'm writing lots of code like this; if (cssTransitions) { $("#content_box").css("height",0); window.setTimeout(function() { secondFunction(); }, 600); } else { $("#content_box").animate({ height:0 }, 600, function() { secondFunction(); }); } I'd much rather write a function that looks like this: function slideUpContent(object) { if (cssTransitions) { object.css("height",0); // Not sure how I get a callback here } else { $("#content_box").animate({ height:0 }, 600, function() { }); } } That I could use like this: slideUpContent("#content_box", function(){ secondFunction(); }); But I'm not sure how to get the functionality I need - namely a way to run another function once my one has completed. Can anyone help my rather addled brain?

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  • Applying transformations to NSBitmapImageRep

    - by Adam
    So ... I have an image loaded into an NSBitmapImageRep object, so I am able to examine the contents of specific pixels via a two dimensional array. Now I want to apply a couple of "transformations" to the image, in preparation for some additional processing. If I was manipulating the image manually, in Photoshop, I would: Rotate the image Crop a portion of it and discard the rest Apply a "threshold" transformation (which essentially converts the image to black and white, based on the threshold value I provide) Resample the image to shrink it down a bit (which, although losing some image quality, will speed up the subsequent processing) (not necessarily in that order) Are there objective C methods available to facilitate these specific image manipulations, with the data in the NSBitmapImageRep object? If so, can someone point me to some good examples?

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  • Asp.Net - Can a LinkButton.CommandArgument be typed?

    - by Stimul8d
    Okay so given a LinkButton inside a the ItemTemplate of a Repeater declared like this - <asp:LinkButton ID="restrictionDelete" runat="server" CssClass="restrictionDelete" Text="Delete..." OnCommand="lnkDeleteRestriction_Command" CommandName="Delete" CommandArgument="<%# Container.DataItem %>"></asp:LinkButton> Now,..the repeater is being bound to a list of Restriction objects so when the lnkDeleteRestriction_Command is fired I'm expecting that I can cast the CommandEventArgs.CommandArgument which is an object to my Restriction type. This doesn't seem to be so,..I just get the fully qualified type name as a string. Can I receive a typed command argument at all and if not, why is it an object? Thanks in advance,

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  • PHP class referencing confusion across multiple files

    - by DssTrainer
    I have an index.php file that has 3 includes <?php require_once('mod.php'); $mod = new Mod(); require_once('start.php'); require_once('tools.php'); ....some code.... ?> I need to be able to reference the $mod object inside the start.php and tools.php. How do I pass that object to be referenced by those 2 other require files? Basically the mod.php is a class that has an array list generated in its __construct(). I want to use that array list data inside the startup.php and tools.php file but not sure how to pass in the existing one without calling "new" inside both of those files separately which doesn't do what I need since it resets everything. Thanks!

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  • how to select specific number of child entities instead of all in entity framework 3.5?

    - by Sasha
    Hi all, i am wondering how can i select specific number of child objects instead of taking them all with include? lets say i have object 'Group' and i need to select last ten students that joined the group. When i use '.Include("Students"), EF includes all students. I was trying to use Take(10), but i am pretty new to EF and programming as well, so i couldn't figure it out. Any suggestions? UPDATED: ok, i have Group object already retrieved from db like this: Group group = db.Groups.FirstOrDefault(x=>x.GroupId == id) I know that i can add Include("Students") statement, but that would bring ALL students, and their number could be quite big whether i need only freshest 10 students. Can i do something like this: var groupWithStudents = group.Students.OrderByDescending(//...).Take(10);? The problem with this is that Take< no longer appears in intellisense. Is this clear enough? Thanks for responses

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  • that, self or me — which one to prefer in JavaScript?

    - by Török Gábor
    While coding JavaScript sometimes you store the reference of object this in a local variable for different purposes (to set proper scope, to help code obfuscators, etc.). There are coders who prefer aliasing this to that to make it obvious its intention. Other guys use self since it's pointing to the object itself. I even saw source codes where me held the reference and it still makes sense. Certainly there are other ones. Which one should I prefer? Is there a convention on which to use or is it only the matter of taste.

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  • Correct approach to validate attributes of an instance of class

    - by systempuntoout
    Having a simple Python class like this: class Spam(object): __init__(self, description, value): self.description = description self.value = value Which is the correct approach to check these constraints: "description cannot be empty" "value must be greater than zero" Should i: 1.validate data before creating spam object ? 2.check data on __init__ method ? 3.create an is_valid method on Spam class and call it with spam.isValid() ? 4.create an is_valid static method on Spam class and call it with Spam.isValid(description, value) ? 5.check data on setters declaration ? 6.... Could you recommend a well designed\Pythonic\not verbose (on class with many attributes)\elegant approach?

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  • C# Read Byte [] to Image

    - by LucasGuitar
    I have an application which I'm adding pictures and these are automatically converted to binary and stored in a single file. how can I save several images, I keep in an XML file start and size of each set of refente to an image byte. But it has several images in bytes, whenever I try to select a different set of bytes just opening the same image. I would like your help to be able to fix this and open different images. Code //Add Image private void btAddImage_Click(object sender, RoutedEventArgs e) { OpenFileDialog op = new OpenFileDialog(); op.Title = "Selecione a Imagem"; op.Filter = "All supported graphics|*.jpg;*.jpeg;*.png|" + "JPEG (*.jpg;*.jpeg)|*.jpg;*.jpeg|" + "Portable Network Graphic (*.png)|*.png"; if (op.ShowDialog() == true) { imgPatch.Source = new BitmapImage(new Uri(op.FileName)); txtName.Focus(); } } //Convert Image private void btConvertImage_Click(object sender, RoutedEventArgs e) { if (String.IsNullOrEmpty(txtName.Text)) { txtName.Focus(); MessageBox.Show("Preencha o Nome", "Error"); } else { save(ConvertFileToByteArray(op.FileName), txtName.Text); } } //Image to Byte Array private static byte[] ConvertFileToByteArray(String FilePath) { return File.ReadAllBytes(FilePath); } //Save Binary File and XML File public void save(byte[] img, string nome) { FileStream f; long ini, fin = img.Length; if (!File.Exists("Escudos.bcf")) { f = new FileStream("Escudos.bcf", FileMode.Create); ini = 0; } else { f = new FileStream("Escudos.bcf", FileMode.Append); ini = f.Length + 1; bin = new TestBinarySegment(); } bin.LoadAddSave("Escudos.xml", "Brasileiro", nome, ini, fin); BinaryWriter b = new BinaryWriter(f); b.Write(img); b.Close(); f.Dispose(); } //Load Image from Byte private void btLoad_Click(object sender, RoutedEventArgs e) { getImageFromByte(); } //Byte to Image public void getImageFromByte(int start, int length) { using (FileStream fs = new FileStream("Escudos.bcf", FileMode.Open)) { byte[] iba = new byte[fs.Length+1]; fs.Read(iba, start, length); Image image = new Image(); image.Source = BitmapFrame.Create(fs, BitmapCreateOptions.None, BitmapCacheOption.OnLoad); imgPatch2.Source = image.Source; } }

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  • Using JLists and ListModels

    - by devoured elysium
    I have defined a DirectoryListModel class that extends the AbstractListModel class from the Java Api. Internally, I have a list of File objects. I have defined the getElementAt(int index) method as: @Override public Object getElementAt(int index) { return directoryElements.get(index) } The problem is that when I try to run my JList with my DirectoryListModel, it is going to show up the full paths of files instead of just the filenames. I could change this code to: @Override public Object getElementAt(int index) { return directoryElements.get(index).getName(); } and it'd work wonders, but the problem is that in the onclick event I'll want to have the File objects so I can do some checking with them (check if they're directories, etc). If I make getElementAt() return a String, I'm losing that possibility, thus I'd like to konw if there is a way I can format my File objects before the JList shows them in my window. Thanks

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  • How do you extend a Ruby module with macro-like metaprogramming methods?

    - by Ian Terrell
    Consider the following extension (the pattern popularized by several Rails plugins over the years): module Extension def self.included(recipient) recipient.extend ClassMethods recipient.class_eval { include InstanceMethods } end module ClassMethods def macro_method puts "Called macro_method within #{self.name}" end end module InstanceMethods def instance_method puts "Called instance_method within #{self.object_id}" end end end If you wished to expose this to every class, you can do the following: Object.send :include, Extension Now you can define any class and use the macro method: class FooClass macro_method end #=> Called macro_method within FooClass And instances can use the instance methods: FooClass.new.instance_method #=> Called instance_method within 2148182320 But even though Module.is_a?(Object), you cannot use the macro method in a module: module FooModule macro_method end #=> undefined local variable or method `macro_method' for FooModule:Module (NameError) This is true even if you explicitly include the original Extension into Module with Module.send(:include, Extension). How do you add macro like methods to Ruby modules?

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  • New records added to DataGridView aren't displayed

    - by Ross
    I have a custom Order class, groups of which are stored in List<Order> and a DataGridView. I think the problem is in my implementation so here's how I'm using it: In the form enclosing DataGridView (as OrdersDataGrid): public partial class MainForm : Form { public static List<Order> Orders; public MainForm() { // code to populate Orders with values, otherwise sets Orders to new List<Order>(); OrdersDataGrid.DataSource = Orders; } Then in another form that adds an Order: // Save event public void Save(object sender, EventArgs e) { Order order = BuildOrder(); // method that constructs an order object from form data MainForm.Orders.Add(order); } From what I can tell from the console this is added successfully. I thought the DataGrid would be updated automatically after this since Orders has changed - is there something I'm missing? The DataGrid accepts the class since it generates columns from the members.

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  • How does Git know which Index blob to add to a tree?

    - by drozzy
    In Pro Git Ch9 the author says: Git normally creates a tree by taking the state of your staging area or index and writing a tree object from it. My question is how does git know which of two consequitive index entries to create the Tree object from? For example: $ echo 'First change' > one.txt $ git add one.txt $ find .git/objects -type f .git/objects/1f/755a7fffe4 //first index entry $ echo 'Second change' > one.txt $ git add one.txt $ find .git/objects -type f .git/objects/2d/234asdf2 //second index entry $ git commit -a -m "Initial commit" $ git cat-file master^{tree} 100644 blob 2d234asdf2 one.txt //How did it know not to take 1f755?? Does it just look at the blob timestamps? Also - what happens to the first blob created - no one is referencing it. Does it just get destroyed or forgotten?

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  • Flex Filterfunction - Filter by Array of values

    - by Anandh
    How to filter an Arraycollection by "array of values" rather than a single value (simple comparision) , the below code snippet is for filtering by single value now I went into scenario like filter out only price [10,4,1,8] (some random values from the master collection). Is there any better way to do the second code snippet Filter function simple comparision private function filterForTestData(item:Object):Boolean{ if(item.price < slider.value) return true; else return false; } Filter by array of values private function filterForTestData(item:Object,filterBy:Array= [10,4,1,8]):Boolean{ for(randomprice in filterBy) return item.price == randomprice; } [Edited] Apply Filter testData.filterFunction = filterForTestData;

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  • Constructors with inheritance in c++

    - by Crystal
    If you have 3 classes, with the parent class listed first shape- 2d shapes, 3d shapes - circle, sphere When you write your constructor for the circle class, would you ever just initialize the parent Shape object and then your current object, skipping the middle class. It seems to me you could have x,y coordinates for Shape and initialize those in the constructor, and initialize a radius in the circle or sphere class, but in 2d or 3d shape classes, I wouldn't know what to put in the constructor since it seems like it would be identical to shape. So is something like this valid Circle::Circle(int x, int y, int r) : Shape(x, y), r(r) {} I get a compile error of: illegal member initialization: 'Shape' is not a base or member So I wasn't sure if my code was legal or best practice even. Or if instead you'd have the middle class just do what the top level Shape class does TwoDimensionalShape::TwoDimensionalShape(int x, int y) : Shape (x, y) {} and then in the Circle class Circle::Circle(int x, int y, int r) : TwoDimensionalShape(x, y), r(r) {}

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  • When to update audit fields? DDD

    - by user676767
    I have a Meeting Object: Meeting{id, name, time, CreatedBy, UpdatedBy} and a MeetingAssignee{id, MeetingID, EmployeeId, CreatedBy, UpdatedBy) Meeting, as Aggregate root, has a method AssignEmployee. I was about to pass in the current user to the Meeting object as I call AssignEmployee, so that it can update its audit fields accordingly. But this doesn't seem right - is it? Obviously I can keep the audit fields public and change them later - perhaps at service level? What is everyone's else preferred method for updating these fields? Please note: We are not using Nhibernate, but a custom ORM which does not have anything automatic in place. Thanks.

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  • Is there an ORM that allows a "plugin" to extend the database?

    - by IP
    So, I've been searching for the answer to this, but I can't find anything I have an Entity Framework Model (MyModel1) - for now, we'll say this contains a "Users" table It's part of a big app, that has a references to an "Addresses" project The addresses project contains an Entity Framework Model (MyModel2), this contains a Users table, and an Addresses table (pointing to the same database. The main app has a control that edits the user, and in that control it has an "addresses" control which actually exists in the "Addresses" project. To make this work, the User control passes the User object down to the addresses control, however, as the User that's been passed belongs to MyModel1 and not MyModel2, another User object has to be loaded up, then it can be used. This isn't ideal as I've had to load up the User twice. Is there a way of say, MyModel2 extending MyModel1, which effectively just adds a relationship to "User". Or is there an ORM that would handle this better? Or even a design pattern that would handle this better?

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  • Returning objects with dynamic memory

    - by Caulibrot
    I'm having trouble figuring out a way to return an object (declared locally within the function) which has dynamic memory attached to it. The problem is the destructor, which runs and deletes the dynamic memory when the object goes out of scope, i.e. when I return it and want to use the data in the memory that has been deleted! I'm doing this for an overloaded addition operator. I'm trying to do something like: MyObj operator+( const MyObj& x, const MyObj& y ) { MyObj z; // code to add x and y and store in dynamic memory of z return z; } My destructor is simply: MyObj::~MyObj() { delete [] ptr; } Any suggestions would be much appreciated!

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  • memset on array of structures in C++

    - by garry
    I have another memset question. It appears as if the code I am editing may have some issues (or it's not done the same way in different files) A::LRM las[9]; //A and LRM are both structures with BOOLS and INTS memset(&las, 0, sizeof(las)); typedef Sec SecArray[16]; SecArray rad_array; memset(rad_array, 0, sizeof(SecArray)); The second example appears to be correct because rad_array is the same as the first position in the array. Then the sizeof(SecArray)) would make sense. The first one doesn't seem correct to me. All structs are just BOOLs and INTS nothing dynamic in them. My understanding from my other post about memset was that it followed this format. memset("pointer to object", "what to set it to", "size of object") Can anyone tell me what exactly is going on here if I am incorrect with my theory.

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  • h:selectOneMenu not populating a 'selected' item

    - by dann.dev
    I'm having trouble with an h:selectOneMenu not having a selected item when there is already something set on the backing bean. I am using seam and have specified a customer converter. When working on my 'creation' page, everything works fine, something from the menu can be selected, and when the page is submitted, the correct value is assigned and persisted to the database as well. However when I work on my 'edit' page the menu's default selection is not the current selection. i have gone through and confirmed that something is definitely set etc. My selectOneMenu looks like this: <h:selectOneMenu id="selVariable" value="#{customer.variableLookup}" converter="#{variableLookupConverter}"> <s:selectItems var="source" value="#{customerReferenceHelper.variableLookups()}" label="#{source.name}" /> </h:selectOneMenu> And the converter is below. It very simple and just turns the id from string to int and back etc: @Name( "sourceOfWealthLookupConverter" ) public class SourceOfWealthLookupConverter implements Serializable, Converter { @In private CustomerReferenceHelper customerReferenceHelper; @Override public Object getAsObject( FacesContext arg0, UIComponent arg1, String arg2 ) { VariableLookup variable= null; try { if ( "org.jboss.seam.ui.NoSelectionConverter.noSelectionValue".equals( arg2 ) ) { return null; } CustomerReferenceHelper customerReferenceHelper = ( CustomerReferenceHelper ) Contexts.getApplicationContext().get( "customerReferenceHelper" ); Integer id = Integer.parseInt( arg2 ); source = customerReferenceHelper.getVariable( id ); } catch ( NumberFormatException e ) { log.error( e, e ); } return variable; } @Override public String getAsString( FacesContext arg0, UIComponent arg1, Object arg2 ) { String result = null; VariableLookup variable= ( VariableLookup ) arg2; Integer id = variable.getId(); result = String.valueOf( id ); return result; } } I've seen a few things about it possibly being the equals() method on the class, (that doesn't add up with everything else working, but I overrode it anyway as below, where the hashcode is just the id (id is a unique identifier for each item). Equals method: @Override public boolean equals( Object other ) { if ( other == null ) { return false; } if ( this == other ) { return true; } if ( !( other instanceof VariableLookup ) ) { return false; } VariableLookup otherVariable = ( VariableLookup ) other; if ( this.hashCode() == otherVariable.hashCode() ) { return true; } return false; } I'm at my wits end with this, I can't find what I could have missed?! Any help would be much appreciated

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  • Passing User Data with SetTimer

    - by GJ
    I am calling SetTimer in a function of a Class. SetTimer(NULL, 0, 10000, (TIMERPROC) TimerCallBack); Where TimerCallBack is: static VOID CALLBACK TimerCallBack(HWND, UINT, UINT, DWORD) Now my need is to call one of the method of class which initiated timer, since TimerCallBack is static it has no access to the class object anymore. I cant find any way to pass object pointer along with the SetTimer so that I can receive it back on Callback function. Is there any other way to achieve this, if its not supported using SetTimer then which other way I can implement this.

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