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  • Iterative / Additive MD5

    - by Andrew Robinson
    I need to generate a checksum over a dictionary. Keys and Values. Is there any simple way to accomplish this in an iterative way. foreach(var item in dic.Keys) checksum += checksum(dic[item]) + checksum(item); In this case, keys and values could be converted to strings, concatinated and then a single checksum applied over these but is there a better way? Ideally MD5 but other options could work. Using this to validate data that is passed over a couple of storage methods. The checksum is then encrypted along with some other information (using AES) so I am not horribly worried about an ideal, unbreakable checksum.

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  • Weird use of generics

    - by Karl Trumstedt
    After a bit of programming one of my classes used generics in a way I never seen before. I would like some opinions of this, if it's bad coding or not. abstract class Base<T> : where T : Base<T> { // omitted methods and properties. virtual void CopyTo(T instance) { /*code*/ } } class Derived : Base<Derived> { override void CopyTo(Derived instance) { base.CopyTo(instance); // copy remaining stuff here } } is this an OK use of generics or not? I'm mostly thinking about the constraint to "itself". I sometimes feel like generics can "explode" to other classes where I use the Base class.

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  • Catching constraint violations in JPA 2.0.

    - by Dennetik
    Consider the following entity class, used with, for example, EclipseLink 2.0.2 - where the link attribute is not the primary key, but unique nontheless. @Entity public class Profile { @Id private Long id; @Column(unique = true) private String link; // Some more attributes and getter and setter methods } When I insert records with a duplicate value for the link attribute, EclipseLink does not throw a EntityExistsException, but throws a DatabaseException, with the message explaining that the unique constraint was violated. This doesn't seem very usefull, as there would not be a simple, database independent, way to catch this exception. What would be the advised way to deal with this? A few things that I have considered are: Checking the error code on the DatabaseException - I fear that this error code, though, is the native error code for the database; Checking the existence of a Profile with the specific value for link beforehand - this obviously would result in an enormous amount of superfluous queries.

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  • Does delegate chaining have to start with a null Delegate?

    - by MCS
    In CLR via C#, Jeffrey Richter gives the following example of delegate chaining (pg. 406): internal delegate void Feedback(Int 32 value); Feedback fb1 = new Feedback(method1); // in the book, these methods Feedback fb2 = new Feedback(method2); // have different names Feedback fb3 = new Feedback(method3); Feedback fbChain = null; fbChain = (Feedback) Delegate.Combine(fbChain, fb1); fbChain = (Feedback) Delegate.Combine(fbChain, fb2); fbChain = (Feedback) Delegate.Combine(fbChain, fb3); Why does the first call to Delegate.Combine have to pass in a null Delegate? Here's how I would have thought it should be written: Feedback fbChain = (Feedback) Delegate.Combine(fb1, fb2); fbChain = (Feedback) Delegate.Combine(fbchain, fb3);

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  • Java: implementation of simple commands

    - by HH
    I have created a pkg for my regular simple commands. They are non-static, to be more extensible, but somewhat more time-consuming to use because of creating object to use one. My other classes use them. $ ls *.java CpF.java IsBinary.java RmLn.java Tools.java F2S.java IsRoot.java SaveToDisk.java WordCount.java Filters.java ModRelativePaths.java SetWord.java WordNumber.java Find.java powerTools.java Sort.java Which option would you choose to use them easier? to develop a small interface like 'powerTools.java' for the pkg. to create a class with static methods for them. to add a static method to each class to stop overusing 'creating too many files' and centralising some? sthing else?

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  • Is it possible to create thread-safe collections without locks?

    - by Andrey
    This is pure just for interest question, any sort of questions are welcome. So is it possible to create thread-safe collections without any locks? By locks I mean any thread synchronization mechanisms, including Mutex, Semaphore, and even Interlocked, all of them. Is it possible at user level, without calling system functions? Ok, may be implementation is not effective, i am interested in theoretical possibility. If not what is the minimum means to do it? EDIT: Why immutable collections don't work. This of class Stack with methods Add that returns another Stack. Now here is program: Stack stack = new ...; ThreadedMethod() { loop { //Do the loop stack = stack.Add(element); } } this expression stack = stack.Add(element) is not atomic, and you can overwrite new stack from other thread. Thanks, Andrey

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  • Modify action names for route collections in Symfony?

    - by James Skidmore
    When creating an sfPropelRouteCollection, how can I edit the action names that the collection will generate? For example: # Routing for "product" CRUD product: class: sfPropelRouteCollection options: model: Product module: product actions: [new, create, edit, update, delete] How can I change the actual action that is called for any of the new/create/edit/update/delete methods? I'd like for them to call "ajaxNew," "ajaxCreate," etc. so the URL would look something like "product/ajaxNew", or the action for "update" would be "ajaxUpdate". Let me know if I need to clarify further. Thanks.

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  • Similar route mapping

    - by Denis Agarev
    I need to map to create controller what must response to two urls: "http://localhost/api/controller?id=1" (where only id value can change) "http://localhost/api/controller/anotherId/someconst" (where anotherId is the only one changing part) i map it to such route: routes.MapHttpRoute("Test", "api/{controller}/{id}/{someconst}", new { controller = "Test", someconst = RouteParameter.Optional }); And have to methods in my controller: public void Get(int id) { ... } public void Get(int anotherId, string someconst ) { ... } It works...But it doesn't look nice...cause "string someconst" is not a param, it's just a const part of url. But if i remove "string someconst" param second url wouldn't work. Is it possible to map one controller to two routes to resolve this urls to make it clear without fake param which is a const in fact?

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  • Reverting back to previous ADT plugin

    - by sdfwer
    Now I was wondering if anyone has been able to accomplish reverting to a previous ADT plugin. The reason for this is because I am using an open source jar and I am getting the following errors on my LogCat such as: unable to resolve virtual method unable to find class referenced in signature unable to resolve new-instance The effect of this causes an error on running my android application on the debugger. I was using android ADT 15 before now I am updated to 17. Please help on finding a solution to resolve the issue. Edit* Forgot to add in The error "java.lang.NoClassDefFoundError". In simple terms it can't find classes or methods the attached jar even though it allows it.

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  • DDD: Trying to code sorting and filtering as it pertains to Poco, Repository, DTO, and DAO using C#?

    - by Dr. Zim
    I get a list of items from my Repository. Now I need to sort and filter them, which I believe would be done in the Repository for efficiency. I think there would be two ways of doing this in a DDD way: Send a filter and a sort object full of conditions to the Repository (What is this called)? Repository result would produce an object with .filter and .sort methods? (This wouldn't be a POJO/POCO because it contains more than one object?). So is the answer 1, 2, or other? Could you explain why? I am leaning toward #1 because the Repository would be able to only send the data I want (or will #2 be able to delay accessing data like a LazyList?) A code example (or website link) would be very helpful. Example: Product product = repo.GetProducts(mySortObject, myFilterObject); // List of Poco product.AddFilter("price", "lessThan", "3.99"); product.AddSort("price", "descending");

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  • Determine Android phone's proximity to known point while conserving power

    - by ahsteele
    I am trying to determine if an Android user has had a close proximity to a list of predetermined locations. I'd like to do this with the least amount of drain on the phone's battery. The two mechanisms I see for accomplishing this are proximity alerts and requesting location updates. What are the pros and cons of the two methods? Will one have less affect on the battery than the other? In either case I would guess the specific location manager used would affect power usage (existing Stack Overflow answer).

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  • net c# lock statement in data access layer

    - by Pedro Rivera
    I saw a code where they have the data access layer like this: public class CustomerDA{ private static readonly object _sync = new object(); private static readonly CustomerDA _mutex = new CustomerDA(); private CustomerDA(){ } public CustomerDA GetInstance(){ lock(_sync){ return _mutex; } } public DataSet GetCustomers(){ //database SELECT //return a DataSet } public int UpdateCustomer(some parameters){ //update some user } } public class CustomerBO{ public DataSet GetCustomers(){ //some bussiness logic return CustomerDA.GetInstance().GetCustomers(); } } I was using it, but start thinking... "and what if had to build a facebook like application where there are hundreds of thousands of concurrent users? would I be blocking each user from doing his things until the previous user ends his database stuff? and for the Update method, is it useful to LOCK THREADS in the app when database engines already manage concurrency at database server level?" Then I started to think about moving the lock to the GetCustomers and UpdateCustomer methods, but think again: "is it useful at all?"

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  • JTabbedPane: only first tab is drawn, the second is always empty (newbie Q)

    - by paul
    I created a very simple JTabbedPane by first creating an empty JTabbedPane object, then 2 JPanels that I later add. Each JPanel is holding a object that extends JButton and implements MouseListener. Each of these holds a different image loaded from a file; the image is held locally as a buffered image and as an image icon, etc., all of which works great. The point of all that is to allow resizing of the image when the button is resized (using getscaledinstance()), because the panel is resized, because the JTabbedPane is resized, etc., within the JFrame that holds everything. I override paintComponent() to accomplish this in the class that extends JButton. I am using MigLayout Manager, and all is well on that front controlling layout constraints, growing, filling, initial sizes, preferred sizes, etc. The images the buttons hold are of different sizes and proportions, but this caused no trouble before. Up until 2 days ago everything worked fairly well. I made some changes trying to tweak some resizing issues as I was picking up MigLayout manager. At the time I was playing around with setting various min, max, and preferred sizes using the methods provided for by the components, not the layout manager. I also fooled a bit with pack(), validate(), visible(), opaque() etc., and yes I read the article about Swing and AWT painting here: http://java.sun.com/products/jfc/tsc/articles/painting/ , and I switched to relying more and more on MigLayout. On an unrelated note, it appears JFrame's do not honor maxsize? Somehow, today, with and without using any of these methods provided by swing, with or without using MigLayout manager to handle some of these matters instead, I now have a JTabbedPane that correctly displays the FIRST JPanel I add, but NOT THE SECOND JPanel--which, while present as a tab--does not show when selected. I have switched the order of which panel is added first, and this still holds true regardless of which JPanel I add first, telling me the JPanels are ok, and the problem is most likely in the JTabbedPane. I click on the second tab, the JTabbedPane switches, but I have what appears to be a blank button in the JPanel. A few console system-out statements reveal the following: a) that the second panel and its button are constructed b) no mouse events are being captured when I click on where the second panel and button should reside, as if it didn't exist at that point; c) when I switch to the second tab, the overrided paintComponent() method of the button within that second JPanel is never called, so it is in fact never being painted despite the tab in which it resides becoming visible; d) the JTabbpedPane getComponentCount() returns a correct value of 2 after adding the 2nd panel; e) MigLayout manager actually rocks, but I digress... I cannot now revert to my older code, and despite my best efforts to undo whatever changes caused this, I cannot fix my new problem. I've commented out everything but the most essential calls: constructors for each object--with MigLayout; add() for placing the buttons on the panels using string-arguments appropriate for MigLayout; add() for placing the panels on the JTabbedPane, also with MigLayout string arguments; setting the default op on close for the JFrame; and setting the JFrame visible. This means I do not fiddle with optimization settings, double buffering settings, opaque settings, but leave them as default, and still, no fix; the second panel will not show itself. Each panel, I should add, when it is the first to be loaded, works fine, again re-affirming that the panels and buttons are themselves ok. Here is part of what I am doing: //Note: BuildaButton is a class that merely constructs my instances File f = new File("/foo.jpg"); button1 = new BuildaButton().BuildaButton(f).buildfoo1Button(); f = new File("/foo2.jpg"); button2 = new BuildaButton().BuildaButton(f).buildfoo2Button(); MigLayout ml = new MigLayout("wrap 1", "[fill, grow]0[fill, grow]", "[fill, grow]0[fill, grow]"); MigLayout ml2 = new MigLayout("wrap 2", "[fill, grow]5[fill, grow]", "[fill, grow]0[fill, grow]"); foo1panel = new JPanel(ml); foo1panel.add(button1, "w 234:945:, h 200:807:"); foo2panel = new JPanel(ml); foo2panel.add(button2, "w 186:752:, h 200:807:"); tabs.add("foo1", foo1panel); tabs.add("foo2", foo2panel); System.out.println("contents of tabs: " + tabs.getComponentCount() + " elements"); mainframe.setLayout(ml2); mainframe.setMinimumSize(new Dimension(850,800)); mainframe.add(tabs, "w 600:800:, h 780:780:"); //controlpanel is a still blank jpanel that holds nothing--it is a space holder for now & will be utilized mainframe.add(controlpanel, "w 200:200:200, h 780:780:"); mainframe.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); mainframe.setVisible(true); Thank you in advance for any help you can give.

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  • What are good ways to guarantee business continuity with a SaaS product?

    - by tommyvdz
    For my Bachelor Thesis I am researching how SaaS providers can arrange some sort of business continuity guarantee. You probably know the Source Code Escrow arrangements for 'shrink-wrapped' software. They give customers access to the source code and all applicable documentation whenever the software supplier gets into (financial) trouble. This clearly does not work for SaaS, because customers have no use for just the source code, and customers probably can not afford not being able to login to their CRM system for a couple weeks because the SaaS provider went bankrupt. I am currently researching different methods to solve this problem. Do you know good and practical solutions to solve this continuity problem? Or companies that already offer a good solution? Thanks!

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  • How does one programmatically create a topic w/ hornet q ?

    - by mP
    I have been looking at the org.hornetq.core.server package which seems to have the most interesting low level APIS relating to managing the server. The server session has a few methods labelled something Queue but none include Topic ... ServerSession void createQueue(SimpleString address, SimpleString name, SimpleString filterString, boolean temporary, boolean durable) throws Exception; void deleteQueue(SimpleString name) throws Exception interface QueueFactory Queue createQueue(long persistenceID, final SimpleString address, SimpleString name, Filter filter, boolean durable, boolean temporary); However i could not figure out how to create a topic. Am i missing something is a JMS topic implemented as a queue ?

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  • delete in tableView..

    - by totato
    I just add this methods in .h file : - (IBAction)EditTable:(id)sender; - (IBAction)DeleteButtonAction:(id)sender; and in .m file : (IBAction)DeleteButtonAction:(id)sender{ [tableList removeLastObject]; [Table reloadData]; } (IBAction) EditTable:(id)sender{ if(self.editing) { [super setEditing:NO animated:NO]; [Table setEditing:NO animated:NO]; [Table reloadData]; [self.navigationItem.leftBarButtonItem setTitle:@"Edit"]; [self.navigationItem.leftBarButtonItem setStyle:UIBarButtonItemStylePlain]; } else { [super setEditing:YES animated:YES]; [Table setEditing:YES animated:YES]; [Table reloadData]; [self.navigationItem.leftBarButtonItem setTitle:@"Done"]; [self.navigationItem.leftBarButtonItem setStyle:UIBarButtonItemStyleDone]; } } when I run the program and click the delete button (red button) the program is stop ! whats the problem ? please any help ?

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  • Creating many new instances vs reusing them?

    - by Hugo Riley
    I have multiple business entities in VB.NET Windows Forms application. Right now they are instanced on application startup and used when needed. They hold descriptions of business entities and methods for storing and retrieving data. To cut the long story short, they are somewhat heavy objects to construct (they have some internal dictionaries and references to other objects) created and held in one big global variable called "BLogic". Should I refactor this so that each object is created when needed and released when out of scope? Then every event on UI will probably create a few of this objects. Should I strive to minimize creation of new objects or to minimize number of static and global objects? Generally I am trying to minimize the scope of every variable but should I treat this business logic objects specially?

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  • jQuery compatible JavaScript documentation generator

    - by clyfe
    I need to choose a documentation generator (similar to jdoc in java or rdoc in ruby) for my javascript project that (built with jquery, underscore and backbone) Candidates: jsdoc toolkit pdoc natural docs docco YUI doc doctool http://jquery.bassistance.de/docTool/docTool.html other ? Requirements should work with jquery, underscore and backbone. that means object-literal methods etc I really like pdoc but its too centered around prototype, poorly documented, and I don't want to make extra files (sections?) to make it work (not sure about this) docco is nice but I want structured output (as in menu + class/func structure like jdoc) must be command line/makefile compatible (not web pastie) Tips, tricks, tutorials, success stories, advice greatly welcomed. Why Doesn't jQuery use JSDoc?

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  • How does struts 1.X ActionForm handle pure html checkbox list?

    - by BlueDolphin
    I am dealing with an old application which uses struts 1.2. And for some reason, we are using pure html form to submit to struts action. For example: for the content output of testAction.do, I try to submit to itself. item 1 item 2 Then I associate an form bean TestForm with testAction. I am not sure how to specify the properties in the form so that it take the value from myitem1 after user click "submit" I tried to add getMyitem1(), setMyitem1(String[] items), getSelectedMyitem1(), setSelectedMyitem1(String[] items) Those set methods are only called when page are loaded. I guess my understanding of ActionForm in struts 1.x must be wrong. Please advise, thanks.

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  • How to isolate data per customer, Django powered website

    - by Sawwy
    I have recently started learning python and django and working on a project that includes building a website for collecting information from customers. I am currently trying to figure out best way to isolate the customer data (collected information is sensitive and should only be accessible by customer and the service provider). I found this post Postgresql - one database for everyone, or one-database per customer and my question is that can I automate the model inheritance with customer creation via admin? To be specific, when save() is called for adding customer via django admin, this should create the customer specific tables (create a new set of tables with 'company_name' -prefix). For more information of the environment, I have extended the basic user registration with custom UserProfile adding 'company' and 'role' fields for each user. Upon login, the 'company' of the user will be checked to filter out tables without the 'company_name' prefix. 'Role' will further filter the which company-specific tables and set rights (view, edit). will appreciate any suggestions if more elegant methods could be used to solve the data isolation problem than model inheritance.

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  • Evaluating Django Chained QuerySets Locally

    - by jnadro52
    Hello All: I am hoping someone can help me out with a quick question I have regarding chaining Django querysets. I am noticing a slow down because I am evaluating many data points in the database to create data trends. I was wondering if there was a way to have the chained filters evaluated locally instead of hitting the database. Here is a (crude) example: pastries = Bakery.objects.filter(productType='pastry') # <--- will obviously always hit DB, when evaluated cannoli = pastries.filter(specificType='cannoli') # <--- can this be evaluated locally instead of hitting the DB when evaluated, as long as pastries was evaluated? I have checked the docs and I do not see anything specifying this, so I guess it's not possible, but I wanted to check with the 'braintrust' first ;-). BTW - I know that I can do this myself by implementing some methods to loop through these datapoints and evaluate the criteria, but there are so many datapoints that my deadline does not permit me manually implementing this. Thanks in advance.

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  • Are there any reasons to make all fields and variables final?

    - by Roman
    In my current project I noticed that all class fields and variable inside methods are declared with final modifier whenever it's possible. Just like here: private final XMLStreamWriter _xmlStreamWriter; private final Marshaller _marshaller; private final OutputStream _documentStream; private final OutputStream _stylesStream; private final XMLStreamWriter _stylesStreamWriter; private final StyleMerger _styleMerger; public DocumentWriter(PhysicalPackage physicalPackage) throws IOException { final Package pkg = new Package(physicalPackage); final Part wordDocumentPart = pkg.createPart( "/word/document.xml", "application/vnd.openxmlformats-officedocument.wordprocessingml.document.main+xml", "http://schemas.openxmlformats.org/officeDocument/2006/relationships/officeDocument"); // styles.xml final Pair<Part, String> wordStylesPart = wordDocumentPart.createRelatedPart(...); ... } Are there any reasons to do so? p.s. As I know project is not supposed to be multithreaded (at least I've heard nothing about it).

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  • Is a base class with shared fields and functions good design

    - by eych
    I've got a BaseDataClass with shared fields and functions Protected Shared dbase as SqlDatabase Protected Shared dbCommand as DBCommand ... //also have a sync object used by the derived classes for Synclock'ing Protected Shared ReadOnly syncObj As Object = New Object() Protected Shared Sub Init() //initializes fields, sets connections Protected Shared Sub CleanAll() //closes connections, disposes, etc. I have several classes that derive from this base class. The derived classes have all Shared functions that can be called directly from the BLL with no instantiation. The functions in these derived classes call the base Init(), call their specific stored procs, call the base CleanAll() and then return the results. So if I have 5 derived classes with 10 functions each, totaling 50 possible function calls, since they are all Shared, the CLR only calls one at a time, right? All calls are queued to wait until each Shared function completes. Is there a better design with having Shared functions in your DAL and still have base class functions? Or since I have a base class, is it better to move towards instance methods within the DAL?

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  • ActiveX communication

    - by Mario Marinato -br-
    I'm developing an ActiveX EXE that exposes an specific class to a third-party software. This third-party software instanciates an object of this class and uses its methods. Strangely, this third-party software destroys its object of my exposed class as soon as it calls an specific method, but I have no idea why this happens. The only clue I have is that this method is the only one that returns a value. All the other ones are simple 'subs' that do not return any value, and when they are called nothing wrong happens. I'm using VB6. Do you guys have any idea of why it's happening?

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  • General zoom algorithm for drawing program

    - by Steven Sproat
    My GUI toolkit, wxPython provides some methods for implementing a user zoom factor, however the quality isn't too good. I'm looking for ideas on how to create a zooming feature, which I know is complicated. I have a bitmap representing my canvas which is drawn to. This is displayed inside a scrolled window. Problems I forsee: - performance when zoomed in and panning around the canvas - difficulties with "real" coordinates and zoomed in coordinates - image quality not degrading with the zoom Using wxPython's SetUserScale() on its device contexts presents image quality like this - this is with a 1px line, at 30% zoomed in. I'm just wondering the general steps I'll need to take and the challenges I'll encounter. Thanks for any suggestions

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