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• ASP.NET MVC Portable Areas - Can they communicate and be used as a plugin-like architecture?

  - by Beton

  I'll get straight to the point: I was wondering if there is a common pattern to use portable areas as a components of a plugin-like architecture. Example: We've got 3 plugins (portable areas) packaged and distributed via NuGet feed. Each of them is following the standard MVC structure (has it own Models, Views and Controllers). Lets say login form, header and footer. What I was wondering if there is a way to make them communicate. For example: when user logs on, login plugin executes it own logic, logs the user and then it updates the state of the header plugin with changes it state accordingly. Thanks in advance.

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• Error handling and polymorphism

  - by Neeraj

  I have an application with some bunch of code like this: errCode = callMainSystem(); switch (errCode){ case FailErr: error("Err corresponding to val1\n"); case IgnoreErr: error("Err corresponding to val2\n"); ... ... default: error("Unknown error\n"); } The values are enum constants. Will it make some sense to have something like: // Error* callMainSystem() ... Some code return FaileErr(); // or some other error // handling code Error* err = callMainSystem(); err->toString(); The Error class may be made singleton as it only has to print error messages. What are the pros and cons of above methods,size is an important criteria as the application needs to be supported on embedded devices as well. P.S: I don't want to use exception handling because of portability issues and associated overheads.

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• Using the StackTrace Class in a production environment to get calling method info

  - by andy

  hey guys We have a "log" class which uses Relection.MethodBase to send current class info to the log. The reflection.MethodBase stuff happens in the class itself. However, I'd like to move that stuff to a single external "log" singleton type class. In this scenario the external log class needs to get the CALLING info, not the current method info. I'm using stacktrace to do this, which isn't in the Reflection namespace. Can I guarantee that "that" specific information (calling method) will be there in a production environment? var stackTrace = new StackTrace(); return LogManager.GetLogger(stackTrace.GetFrame(1).GetMethod().DeclaringType); cheers!

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• What's the point of having to provide a cacheName for NSFetchedResultsController?

  - by dontWatchMyProfile

  NSFetchedResultsController *frc = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:moc sectionNameKeyPath:nil cacheName:@"Root"]; Why do we have to think about a cacheName? How important is this decision? What would happen if there are two NSFetchedResultsController instances using the exact same cacheName? Does that matter? Is that some kind of singleton stuff? Thinking about Core Animation, there's also this strange animationID parameter, but setting it to the exact same thing for dozens of simultaneous animations doesn't hurt the animations at all. So I guess it's probably the same thing here...or not?

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• Is it okay to have many Abstract classes in your application?

  - by JoseK

  We initially wanted to implement a Strategy pattern with varying implementations of the methods in a commmon interface. These will get picked up at runtime based on user inputs. As it's turned out, we're having Abstract classes implementing 3 - 5 common methods and only one method left for a varying implementation i.e. the Strategy. Update: By many abstract classes I mean there are 6 different high level functionalities i.e. 6 packages , and each has it's Interface + AbstractImpl + (series of Actual Impl). Is this a bad design in any way? Any negative views in terms of later extensibility - I'm preparing for a code/design review with seniors.

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• Dell Vostro 1510 trackpad

  - by user18055

  A week ago I moved totally from Windows 7 to Ubuntu. I've been really happy with the transition bar one annoying glitch. My trackpad sometimes works, sometimes doesn't. All other hardware including peripherals work flawlessly, including a Logitech ball mouse, Wacom Bamboo pen and touch and wireless Logitech keyboard and mouse combo. I can't see any pattern to when and why the trackpad works. Occasionally on rebooting, it will work, but then I can reboot 10x in a row and it won't work, then I leave it a day, then reboot and it works flawlessly. Any ideas on a solution or appropriate method for me to deb it? My knowledge of Ubuntu/Linux is sketchy at best so I could do with a little help :)

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• How do I reuse a state machine in a slightly different way?

  - by JoJo

  Problem I have a big state machine. The design requirements of the project have changed such that I need to re-use this state machine in another place. All the states remain the same in this new place, but a few states run slightly different stuff. What design pattern allows me to reuse this state machine? Motivation I am building a video player. It is modeled by a state machine with these states: stopped, loading, playing, paused, crashed, and some more... This video player needs to be used on two web pages. When the player crashes on the first page, it should show an error message below. If the player crashes on the second page, the error message should appear in the center of the video and pulsate a few times.

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• Dash search does not show applications

  - by To Do

  Since the upgrade (actually a fresh install) to 13.10, many times, when I open Dash and search for an application I only get results for files and folders. Sometimes I get some applications but not others. I haven't found a pattern to replicate the issue 100%. If I open the application lens and search again, it works as it should. So many times, to launch an application, I have to use the super + a key combination to open the application scope instead of the simply the super key. It is annoying. Did anyone have the same issue? I searched for bugs on launchpad but didn't find any. I didn't open a bug report yet because it is not clear how to reproduce the problem faithfully. Even more importantly, does anyone have a solution to this issue?

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• Figuring out the Call chain

  - by BDotA

  Let's say I have an assemblyA that has a method which creates an instance of assemblyB and calls its MethodFoo(). Now assemblyB also creates an instance of assemblyC and calls MethodFoo(). So no matter if I start with assemblyB in the code flow or with assemlyA, at the end we are calling that MethodFoo of AssemblyC(). My question is when I am in the MethodFoo() how can I know who has called me? Has it been a call originally from assemblyA or was it from assemlyB? Is there any design pattern or a good OO way of solving this?

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• Is OOP becoming easier or harder?

  - by tunmise fasipe

  When the concepts of Object Oriented Programming were introduced to programmers years back it looks interesting and programming was cleaner. OOP was like this Stock stock = new Stock(); stock.addItem(item); stock.removeItem(item); That was easier to understand with self-descriptive name. But now OOP, with pattern like Data Transfer Objects (or Value Objects), Repository, Dependency Injection etc, has become more complex. To achieve the above you may have to create several classes (e.g. abstract, factory, DAO etc) and Implement several interfaces Note: I am not against best practices that makes Collaboration, Testing and Integration easier

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• How to generate "language-safe" UUIDs?

  - by HappyDeveloper

  I always wanted to use randomly generated strings for my resources' IDs, so I could have shorter URLs like this: /user/4jz0k1 But I never did, because I was worried about the random string generation creating actual words, eg: /user/f*cker. This brings two problems: it might be confusing or even offensive for users, and it could mess with the SEO too. Then I thought all I had to do was to set up a fixed pattern like adding a number every 2 letters. I was very happy with my 'generate_safe_uuid' method, but then I realized it was only better for SEO, and worse for users, because it increased the ratio of actual words being generated, eg: /user/g4yd1ck5 Now I'm thinking I could create a method 'replace_numbers_with_letters', and check that it haven't formed any words against a dictionary or something. Any other ideas? ps. As I write this, I also realized that checking for words in more than one language (eg: english and french, spanish, etc) would be a mess, and I'm starting to love numbers-only IDs again.

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• Javascript: variable scope & the evils of globals

  - by Nick

  I'm trying to be good, I really am, but I can't see how to do it :) Any advice on how to not use a global here would be greatly appreciated. Let's call the global G. Function A Builds G by AJAX Function B Uses G Function C Calls B Called by numerous event handlers attached to DOM elements (type 1) Function D Calls B Called by numerous event handlers attached to DOM elements (type 2) I can't see how I can get around using a global here. The DOM elements (types 1 & 2) are created in other functions (E&F) which are unconnected with A. I don't want to add G to each event handler (because it's large and there's lots of these event handlers), and doing so would require the same kind of solution as I'm seeking here (i.e., getting G to E&F). The global G, BTW, is an array that is necessary to build other elements as they, in turn, are built by AJAX. I'm not convinced that a singleton is real solution, either. Thanks.

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• How to configure Spring-DM OSGi service for new instance per call?

  - by Bhav

  I'm starting to delve into using Spring DM and OSGi services in an RCP application. I've created a service which is used by another bundle in the RCP application. It does a lookup of the service via calls to getBundleContext().getServiceReference() using the explicit bundle names and service class names. I'm not using DI anywhere yet. The issue I'm running into is that the service that is returned in the requesting bundle is a singleton. At times I notice a threading issue since it is a "stateful" service. How do I configure the application to get back a new service instance with each call? Here is my spring xml file contents which registers the service: <bean id="myServBean" class="com.xyz.ClassImpl"/> <osgi:service ref="myServBean" class="com.xyz.Class"/>

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• What is this called?

  - by robertlewis2001

  I'm hoping there's a book or something out there for me to get... If I have a class that has Collection as an instance variable, what is that method of coding called? A design pattern? If so, where can I find more information on it? As I've been working with this mentor, he's really helped me understand my programming weakness and that weakness is thinking in terms of collections or relationships between objects. It just seems so difficult for me right now and I need to read to become smarter. My mentor is a great guy, but he gets frustrated when I start asking lots of questions, so I'm starting to feel like I need to learn more on my own. public class Evaluation { private List<Criterion> criterion = null; public Evaluation() { criterion = new List<Criterion>(); } }

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• What version will be chosen by MSXML2.XMLHTTP request, without version suffix? [migrated]

  - by jayarjo

  Probably every web developer is familiar with a pattern like this: var xmlHttp = null; if (window.XMLHttpRequest) { // If IE7, Mozilla, Safari, and so on: Use native object. xmlHttp = new XMLHttpRequest(); } else { if (window.ActiveXObject) { // ...otherwise, use the ActiveX control for IE5.x and IE6. xmlHttp = new ActiveXObject('MSXML2.XMLHTTP'); } } But the question is - if there are multiple MSXML versions available on the client's PC (let's say 3.0, 5.0, 6.0), which one of them will be chosen by MSXML2.XMLHTTP call (notice no version suffix at the end)? Will it be the latest or - not necessarily? And a side-question - is it possible to check which version was chosen?

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• How to synchronize static method in java.

  - by Summer_More_More_Tea

  Hi there: I come up with this question when implementing singleton pattern in Java. Even though the example listed blow is not my real code, yet very similar to the original one. public class ConnectionFactory{ private static ConnectionFactory instance; public static synchronized ConnectionFactory getInstance(){ if( instance == null ){ instance = new ConnectionFactory(); } return instance; } private ConnectionFactory(){ // private constructor implementation } } Because I'm not quite sure about the behavior of a static synchronized method, I get some suggestion from google -- do not have (or as less as possible) multiple static synchronized methods in the same class. I guess when implementing static synchronized method, a lock belongs to Class object is used so that multiple static synchronized methods may degrade performance of the system. Am I right? or JVM use other mechanism to implement static synchronized method? What's the best practice if I have to implement multiple static synchronized methods in a class? Thank you all! Kind regards!

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• My laptop doesn't always boot to login

  - by GUI Junkie

  I have an recurring problem. Every once in a while, no pattern, the laptop freezes during boot. Sometimes at a black screen, sometimes a black screen with a not blinking cursor... The solution is to power down the laptop, cross my fingers and boot again. Sometimes it takes four or five reboots, but in the end I always get the system up and running. What bugs me is the fact that the boot is not 'stable' in a sense that apparently it doesn't always do exactly the same thing. I'm still using 10.10. The question is whether there is anything that can be done to make the system stable. (Does 11.04 have the same issue?) Edit: Today the same thing happened. First a black screen with a non blinking cursor. Second a black screen. Third login screen.

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• Processing a list of atomic operations, allowing for interruptions

  - by JDB

  I'm looking for a design pattern that addresses the following situation: There exists a list of tasks that must be processed. Tasks may be added at any time. Each task is wholly independent from all other tasks. The order in which tasks are processed has no effect on the overall system or on the tasks themselves. Every task must be processed once and only once. The "main" process which launches the task processors may start and stop without warning. When stopped, the "main" process loses all in-memory data. Obviously this is going to involve some state, but are there any design patterns which discuss where and how to maintain that state? Are there any relevant anti-patterns? Named patterns are especially helpful so that we can discuss this topic with other organizations without having to describe the entire problem domain.

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• Why do most of us use 'i' as a loop counter variable?

  - by kprobst

  Has anyone thought about why so many of us repeat this same pattern using the same variable names? for (int i = 0; i < foo; i++) { // ... } It seems most code I've ever looked at uses i, j, k and so on as iteration variables. I suppose I picked that up from somewhere, but I wonder why this is so prevalent in software development. Is it something we all picked up from C or something like that? Just an itch I've had for a while in the back of my head.

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• MVC? patterns for game development? [closed]

  - by davivid

  Possible Duplicate: MVC-like compartmentalization in games? I am thinking of the best way to structure my project and was thought a MVC style pattern would be appropriate. Would be correct having the model handle the majority and basically being the game engine? Are there any standardised patterns recommended for simple game development? Model / Game Engine Data: Level Design, Chat feeds, etc Game Status: Player status, Enemy status, World Status etc etc. Engine: Physics, Collisions, AI View 3D: Gameplay, Camera, Rendering... 2D: UI etc Controller: Player Input UI Input

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• Repositories and the Save Method

  One of the questions I've been getting lately goes like this: Should a Repository class have a Save method? And the standard answer: It depends. It's hard to keep track of all the different approaches to implementing the repository pattern these days, but I assume when someone asks me this type of question they are thinking of using code like this: var employee = new Employee(); employeeRepository.Save(employee); var account = new Account(); accountRepository.Save(account); This...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• What are the caveats of the event system built on Messenger rather than on classic .NET events?

  - by voroninp

  MVVM Light and PRISM offer messenger to implement event system. the approximate interface looks like the following one: interface Messanger { void Subscribe<TMessageParam>(Action<TMessageParam> action); void Unsubscribe<TMessageParam>(Action<TMessageParam> action); void Unsubscribe<TMessageParam>(objec actionOwner); void Notify<TMessageParam>(TMessageParam param); } Now this model seems beneficial comparing to classic .net events. It works well with Dependency Injection. Actions are stored as weak references so memory leaks are avioded and unsubscribe is not a must. The only annoyance is the need to declare new TMessageParam for each specific message. But everything comes at a cost. And what I'm really worried about is that I see no shortcomings of this approach. Has anoyne the experience of some troubles with this design pattern?

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• Get and set accessors do they protect different instances of a variable?

  - by Chris Halcrow

  The standard method of implementing get and set accessors in C# and VB.NET is to use a public property to set and retrieve the value of a corresponding private variable. Am I right in saying that this has no effect of different instances of a variable? By this I mean, if there are different instantiations of an object, then those instances and their properties are completely independent right? So I think my understanding is correct that setting a private variable is just a construct to be able to implement the get and set pattern? Never been 100% sure about this.

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• How to trigger code on two different servers in a WAS cluster?

  - by Dean J

  I have an administrative page in a web application that resets the cache, but it only resets the cache on the current JVM. The web application is deployed as a cluster to two WAS servers. Any way that I can elegantly have the "clear cache" button on each server trigger the method on both JVMs? Edit: The original developer just wrote a singleton holding a HashMap to be the cache in question. Lightweight and (previously) worked just fine for the requirements. It caches content pulled from six or seven web services for specified amounts of time. Edit: The entire application in question is three pages, so the elegant solution might well be the lightest solution.

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• Eclipse Plugin: Enablement of an Action based on the current selection - before the

  - by Itay

  Here's my problem: I am using the org.eclipse.ui.popupMenus extension point for adding a sub-menu whose Action that is bounded to the following class: public class MyAction implements IObjectActionDelegate { private Logic logic = Logic.getInstance(); // Singleton public void setActivePart(IAction a, IWorkbenchPart targetPart) { // Nothing here } public void run(IAction a) { // Do something... } public void selectionChanged(IAction a, ISelection s) { a.setEnabled(logic.isEnabled(s)); } } This action is working correctly in most cases (including the call a.setEnabled() in selectionChanged()). My problem at the very first time my action is being invoked. The selectionChanged method is called only after the menu item has been displayed (and not when the user has made the selection) which means that the call to a.setEnabled() will have no affect. Any ideas on how to make my action receive selectionChanged() notifications even before the fist time it is being invoked?

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